Configuration and TuningChernLeeWritten by MikeSmithBased on a tutorial written by MattDillonAlso based on tuning(7) written by Synopsissystem configurationsystem optimizationOne of the important aspects of &os; is proper system
configuration. This chapter explains much of the &os;
configuration process, including some of the parameters which
can be set to tune a &os; system.After reading this chapter, you will know:The basics of rc.conf configuration
and /usr/local/etc/rc.d startup
scripts.How to configure and test a network card.How to configure virtual hosts on network
devices.How to use the various configuration files in
/etc.How to tune &os; using &man.sysctl.8; variables.How to tune disk performance and modify kernel
limitations.Before reading this chapter, you should:Understand &unix; and &os; basics
().Be familiar with the basics of kernel configuration and
compilation ().Starting ServicesTomRhodesContributed by servicesMany users install third party software on &os; from the
Ports Collection and require the installed services to be
started upon system initialization. Services, such as
mail/postfix or
www/apache22 are just two of the many
software packages which may be started during system
initialization. This section explains the procedures available
for starting third party software.In &os;, most included services, such as &man.cron.8;, are
started through the system start up scripts.Extended Application ConfigurationNow that &os; includes rc.d,
configuration of application startup is easier and provides
more features. Using the key words discussed in
, applications can be set to
start after certain other services and extra flags can be
passed through /etc/rc.conf in place of
hard coded flags in the start up script. A basic script may
look similar to the following:#!/bin/sh
#
# PROVIDE: utility
# REQUIRE: DAEMON
# KEYWORD: shutdown
. /etc/rc.subr
name=utility
rcvar=utility_enable
command="/usr/local/sbin/utility"
load_rc_config $name
#
# DO NOT CHANGE THESE DEFAULT VALUES HERE
# SET THEM IN THE /etc/rc.conf FILE
#
utility_enable=${utility_enable-"NO"}
pidfile=${utility_pidfile-"/var/run/utility.pid"}
run_rc_command "$1"This script will ensure that the provided
utility will be started after the
DAEMON pseudo-service. It also provides a
method for setting and tracking the process ID
(PID).This application could then have the following line placed
in /etc/rc.conf:utility_enable="YES"This method allows for easier manipulation of command
line arguments, inclusion of the default functions provided
in /etc/rc.subr, compatibility with
&man.rcorder.8;, and provides for easier configuration via
rc.conf.Using Services to Start ServicesOther services can be started using &man.inetd.8;.
Working with &man.inetd.8; and its configuration is
described in depth in
.In some cases, it may make more sense to use
&man.cron.8; to start system services. This approach
has a number of advantages as &man.cron.8; runs these
processes as the owner of the &man.crontab.5;. This allows
regular users to start and maintain their own
applications.The @reboot feature of &man.cron.8;,
may be used in place of the time specification. This causes
the job to run when &man.cron.8; is started, normally during
system initialization.Configuring &man.cron.8;TomRhodesContributed by cronconfigurationOne of the most useful utilities in &os; is &man.cron.8;.
This utility runs in the background and regularly checks
/etc/crontab for tasks to execute and
searches /var/cron/tabs for custom
&man.crontab.5; files. These files store information about
specific functions which &man.cron.8; is supposed to perform at
certain times.Two different types of configuration files are used by
&man.cron.8;: the system crontab and user
crontabs. These formats only differ in the
sixth field and later. In the system
crontab, &man.cron.8; runs the command as
the user specified in the sixth field. In a user
crontab, all commands run as the user who
created the crontab, so the sixth field is
the last field; this is an important security feature. The
final field is always the command to run.User crontabs allow individual users to schedule tasks
without the need for
root privileges.
Commands in a user's crontab run with the permissions of the
user who owns the crontab.The root user
can have a user crontab just like any
other user. The
root user
crontab is separate from the system
crontab,
/etc/crontab. Because the system
crontab invokes the specified commands as
root, there is
usually no need to create a user crontab
for root.Here is a sample entry from
/etc/crontab:# /etc/crontab - root's crontab for FreeBSD
#
# $FreeBSD$
#
#
SHELL=/bin/sh
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin
#
#minute hour mday month wday who command
#
*/5 * * * * root /usr/libexec/atrun Like most &os; configuration files, lines that begin
with the # character are comments. A
comment can be placed in the file as a reminder of what and
why a desired action is performed. Comments cannot be on
the same line as a command or else they will be interpreted
as part of the command; they must be on a new line. Blank
lines are ignored.The equals (=) character is used to
define any environment settings. In this example, it is
used to define the SHELL and
PATH. If the SHELL is
omitted, &man.cron.8; will use the default of &man.sh.1;.
If the PATH is omitted, no default will be
used and file locations will need to be absolute.This line defines a total of seven fields:
minute,
hour, mday,
month, wday,
who, and command.
These are almost all self explanatory.
minute is the time in minutes when the
specified command will be run. hour is
the hour when the specified command will be run.
mday stands for day of the month and
month designates the month. The
wday option stands for day of the week.
These fields must be numeric values, representing the
twenty-four hour clock, or a *,
representing all values for that field. The
who field only exists in the system
crontab. This field specifies which user the command
should be run as. The last field is the command to be
executed.This last line defines the values discussed above.
This example has a */5 listing,followed
by several more * characters. These
* characters mean
first-last, and can be interpreted as
every time. In this example,
&man.atrun.8; is invoked by
root every five
minutes, regardless of the day or month.Commands can have any number of flags passed to them;
however, commands which extend to multiple lines need to be
broken with the backslash \ continuation
character.This is the basic setup for every &man.crontab.5;.
However, field number six, which specifies the username, only
exists in the system &man.crontab.5;. This field should be
omitted for individual user &man.crontab.5; files.Installing a CrontabDo not use the procedure described here to edit and
install the system crontab,
/etc/crontab. Instead, use an editor
and &man.cron.8; will notice that the file has changed and
immediately begin using the updated version. See this
FAQ entry for more information.To install a freshly written user &man.crontab.5;, use
an editor to create and save a file in the proper format.
Then, specify the file name with &man.crontab.1;:&prompt.user; crontab crontab-fileIn this example, crontab-file is the
filename of a &man.crontab.5; that was previously
created.To list installed &man.crontab.5; files, pass
to &man.crontab.1;.Users who wish to begin their own
crontab file from scratch, without the
use of a template, can use crontab -e.
This will invoke the default editor with an empty file. When
this file is saved, it will be automatically installed by
&man.crontab.1;.In order to remove a user &man.crontab.5; completely,
use crontab -r.Managing Services in &os;TomRhodesContributed by &os; uses the &man.rc.8; system of startup scripts during
system initialization and for managing services. The scripts
listed in /etc/rc.d provide basic services
which can be controlled with the ,
, and options to
&man.service.8;. For instance, &man.sshd.8; can be restarted
with the following command:&prompt.root; service sshd restartThis procedure can be used to start services on a running
system. Services will be started automatically at boot time
as specified in &man.rc.conf.5;. For example, to enable
&man.natd.8; at system startup, add the following line to
/etc/rc.conf:natd_enable="YES"If a line is already
present, change the NO to
YES. The &man.rc.8; scripts will
automatically load any dependent services during the next boot,
as described below.Since the &man.rc.8; system is primarily intended to start
and stop services at system startup and shutdown time, the
, and
options will only perform their action
if the appropriate /etc/rc.conf variable
is set. For instance, sshd restart will
only work if sshd_enable is set to
in /etc/rc.conf.
To , or
a service regardless of the settings
in /etc/rc.conf, these commands should be
prefixed with one. For instance, to restart
&man.sshd.8; regardless of the current
/etc/rc.conf setting, execute the following
command:&prompt.root; service sshd onerestartTo check if a service is enabled in
/etc/rc.conf, run the appropriate
&man.rc.8; script with . This example
checks to see if &man.sshd.8; is enabled in
/etc/rc.conf:&prompt.root; service sshd rcvar
# sshd
#
sshd_enable="YES"
# (default: "")The # sshd line is output from the
above command, not a
root console.To determine whether or not a service is running, use
. For instance, to verify that
&man.sshd.8; is running:&prompt.root; service sshd status
sshd is running as pid 433.In some cases, it is also possible to
a service. This attempts to send a
signal to an individual service, forcing the service to reload
its configuration files. In most cases, this means sending
the service a SIGHUP signal. Support for
this feature is not included for every service.The &man.rc.8; system is used for network services and it
also contributes to most of the system initialization. For
instance, when the
/etc/rc.d/bgfsck script is executed, it
prints out the following message:Starting background file system checks in 60 seconds.This script is used for background file system checks,
which occur only during system initialization.Many system services depend on other services to function
properly. For example, &man.yp.8; and other
RPC-based services may fail to start until
after the &man.rpcbind.8; service has started. To resolve this
issue, information about dependencies and other meta-data is
included in the comments at the top of each startup script.
The &man.rcorder.8; program is used to parse these comments
during system initialization to determine the order in which
system services should be invoked to satisfy the
dependencies.The following key word must be included in all startup
scripts as it is required by &man.rc.subr.8; to
enable the startup script:PROVIDE: Specifies the services this
file provides.The following key words may be included at the top of each
startup script. They are not strictly necessary, but are
useful as hints to &man.rcorder.8;:REQUIRE: Lists services which are
required for this service. The script containing this key
word will run after the specified
services.BEFORE: Lists services which depend
on this service. The script containing this key word will
run before the specified
services.By carefully setting these keywords for each startup script,
an administrator has a fine-grained level of control of the
startup order of the scripts, without the need for
runlevels used by some &unix; operating
systems.Additional information can be found in &man.rc.8; and
&man.rc.subr.8;. Refer to this article
for instructions on how to create custom &man.rc.8;
scripts.Managing System-Specific Configurationrc filesrc.confThe principal location for system configuration
information is /etc/rc.conf. This file
contains a wide range of configuration information and it is
read at system startup to configure the system. It provides
the configuration information for the
rc* files.The entries in /etc/rc.conf override
the default settings in
/etc/defaults/rc.conf. The file
containing the default settings should not be edited.
Instead, all system-specific changes should be made to
/etc/rc.conf.A number of strategies may be applied in clustered
applications to separate site-wide configuration from
system-specific configuration in order to keep administration
overhead down. The recommended approach is to place
system-specific configuration into
/etc/rc.conf.local. For example, these
entries in /etc/rc.conf apply to all
systems:sshd_enable="YES"
keyrate="fast"
defaultrouter="10.1.1.254"Whereas these systems in
/etc/rc.conf.local apply to this system
only:hostname="node1.example.org"
ifconfig_fxp0="inet 10.1.1.1/8"Distribute /etc/rc.conf to every
system using rsync or a similar program,
while /etc/rc.conf.local remains
unique.Upgrading the system will not overwrite
/etc/rc.conf, so system configuration
information will not be lost.The configuration in /etc/rc.conf
is parsed by &man.sh.1;. This allows system operators to
create complex configuration scenarios. Refer to
&man.rc.conf.5; for further information on this
topic.Setting Up Network Interface CardsMarcFonvieilleContributed by network cardsconfigurationAdding and configuring a network interface card
(NIC) is a common task for any &os;
administrator.Locating the Correct Drivernetwork cardsdriverFirst, determine the model of the NIC
and the chip it uses. &os; supports a wide variety of
NICs. Check the Hardware Compatibility
List for the &os; release to see if the NIC
is supported.If the NIC is supported, determine
the name of the &os; driver for the NIC.
Refer to /usr/src/sys/conf/NOTES and
/usr/src/sys/arch/conf/NOTES
for the list of NIC drivers with some
information about the supported chipsets. When in doubt, read
the manual page of the driver as it will provide more
information about the supported hardware and any known
limitations of the driver.The drivers for common NICs are
already present in the GENERIC kernel,
meaning the NIC should show up during boot.
In this example, two NICs using the
&man.dc.4; driver are present on the system:dc0: <82c169 PNIC 10/100BaseTX> port 0xa000-0xa0ff mem 0xd3800000-0xd38
000ff irq 15 at device 11.0 on pci0
miibus0: <MII bus> on dc0
bmtphy0: <BCM5201 10/100baseTX PHY> PHY 1 on miibus0
bmtphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
dc0: Ethernet address: 00:a0:cc:da:da:da
dc0: [ITHREAD]
dc1: <82c169 PNIC 10/100BaseTX> port 0x9800-0x98ff mem 0xd3000000-0xd30
000ff irq 11 at device 12.0 on pci0
miibus1: <MII bus> on dc1
bmtphy1: <BCM5201 10/100baseTX PHY> PHY 1 on miibus1
bmtphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
dc1: Ethernet address: 00:a0:cc:da:da:db
dc1: [ITHREAD]If the driver for the NIC is not
present in GENERIC, but a driver is
available, the driver will need to be loaded before the
NIC can be configured and used. This may
be accomplished in one of two ways:The easiest way is to load a kernel module for the
NIC using &man.kldload.8;. To also
automatically load the driver at boot time, add the
appropriate line to
/boot/loader.conf. Not all
NIC drivers are available as
modules.Alternatively, statically compile support for the
NIC into a custom kernel. Refer to
/usr/src/sys/conf/NOTES,
/usr/src/sys/arch/conf/NOTES and the
manual page of the driver to determine which line to add
to the custom kernel configuration file. For more
information about recompiling the kernel, refer to
. If the
NIC was detected at boot, the kernel
does not need to be recompiled.Using &windows; NDIS DriversNDISNDISulator&windows; driversµsoft.windows;device driversKLD (kernel loadable
object)Unfortunately, there are still many vendors that do not
provide schematics for their drivers to the open source
community because they regard such information as trade
secrets. Consequently, the developers of &os; and other
operating systems are left with two choices: develop the
drivers by a long and pain-staking process of reverse
engineering or using the existing driver binaries available
for µsoft.windows; platforms.&os; provides native support for the
Network Driver Interface Specification
(NDIS). It includes &man.ndisgen.8;
which can be used to convert a &windowsxp; driver into a
format that can be used on &os;. Because the &man.ndis.4;
driver uses a &windowsxp; binary, it only runs on &i386;
and amd64 systems. PCI, CardBus,
PCMCIA, and USB
devices are supported.To use &man.ndisgen.8;, three things are needed:&os; kernel sources.A &windowsxp; driver binary with a
.SYS extension.A &windowsxp; driver configuration file with a
.INF extension.Download the .SYS and
.INF files for the specific
NIC. Generally, these can be found on
the driver CD or at the vendor's website. The following
examples use W32DRIVER.SYS and
W32DRIVER.INF.The driver bit width must match the version of &os;.
For &os;/i386, use a &windows; 32-bit driver. For
&os;/amd64, a &windows; 64-bit driver is needed.The next step is to compile the driver binary into a
loadable kernel module. As
root, use
&man.ndisgen.8;:&prompt.root; ndisgen /path/to/W32DRIVER.INF /path/to/W32DRIVER.SYSThis command is interactive and prompts for any extra
information it requires. A new kernel module will be
generated in the current directory. Use &man.kldload.8;
to load the new module:&prompt.root; kldload ./W32DRIVER_SYS.koIn addition to the generated kernel module, the
ndis.ko and
if_ndis.ko modules must be loaded.
This should happen automatically when any module that
depends on &man.ndis.4; is loaded. If not, load them
manually, using the following commands:&prompt.root; kldload ndis
&prompt.root; kldload if_ndisThe first command loads the &man.ndis.4; miniport driver
wrapper and the second loads the generated
NIC driver.Check &man.dmesg.8; to see if there were any load
errors. If all went well, the output should be similar to
the following:ndis0: <Wireless-G PCI Adapter> mem 0xf4100000-0xf4101fff irq 3 at device 8.0 on pci1
ndis0: NDIS API version: 5.0
ndis0: Ethernet address: 0a:b1:2c:d3:4e:f5
ndis0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
ndis0: 11g rates: 6Mbps 9Mbps 12Mbps 18Mbps 36Mbps 48Mbps 54MbpsFrom here, ndis0 can be
configured like any other NIC.To configure the system to load the &man.ndis.4; modules
at boot time, copy the generated module,
W32DRIVER_SYS.ko, to
/boot/modules. Then, add the following
line to /boot/loader.conf:W32DRIVER_SYS_load="YES"Configuring the Network Cardnetwork cardsconfigurationOnce the right driver is loaded for the
NIC, the card needs to be configured. It
may have been configured at installation time by
&man.sysinstall.8;.To display the NIC configuration,
enter the following command:&prompt.user; ifconfig
dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:da
inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
dc1: flags=8802<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:db
inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255
media: Ethernet 10baseT/UTP
status: no carrier
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
nd6 options=3<PERFORMNUD,ACCEPT_RTADV>In this example, the following devices were
displayed:dc0: The first Ethernet
interface.dc1: The second Ethernet
interface.lo0: The loopback
device.&os; uses the driver name followed by the order in which
the card is detected at boot to name the
NIC. For example,
sis2 is the third
NIC on the system using the &man.sis.4;
driver.In this example, dc0 is up and
running. The key indicators are:UP means that the card is
configured and ready.The card has an Internet (inet)
address, 192.168.1.3.It has a valid subnet mask
(netmask), where
0xffffff00 is the
same as 255.255.255.0.It has a valid broadcast address, 192.168.1.255.The MAC address of the card
(ether) is 00:a0:cc:da:da:da.The physical media selection is on autoselection mode
(media: Ethernet autoselect (100baseTX
<full-duplex>)). In this example,
dc1 is configured to run with
10baseT/UTP media. For more
information on available media types for a driver, refer
to its manual page.The status of the link (status) is
active, indicating that the carrier
signal is detected. For dc1, the
status: no carrier status is normal
when an Ethernet cable is not plugged into the
card.If the &man.ifconfig.8; output had shown something similar
to:dc0: flags=8843<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:da
media: Ethernet autoselect (100baseTX <full-duplex>)
status: activeit would indicate the card has not been configured.The card must be configured as
root. The
NIC configuration can be performed from the
command line with &man.ifconfig.8; but will not persist after
a reboot unless the configuration is also added to
/etc/rc.conf. Add a line for each
NIC present on the system, as seen in this
example:ifconfig_dc0="inet 192.168.1.3 netmask 255.255.255.0"
ifconfig_dc1="inet 10.0.0.1 netmask 255.255.255.0 media 10baseT/UTP"Replace dc0 and
dc1 and the IP
address information with the correct values for the system.
Refer to the man page for the driver, &man.ifconfig.8;, and
&man.rc.conf.5; for more details about the allowed options and
the syntax of /etc/rc.conf.If the network was configured during installation, some
entries for the NIC(s) may be already
present. Double check /etc/rc.conf
before adding any lines.If the network is not using DNS, edit
/etc/hosts to add the names and
IP addresses of of the hosts on the
LAN, if they are not already there. For
more information, refer to &man.hosts.5; and to
/usr/share/examples/etc/hosts.If there is no DHCP server and
access to the Internet is needed, manually configure the
default gateway and the nameserver:&prompt.root; echo 'defaultrouter="your_default_router"' >> /etc/rc.conf
&prompt.root; echo 'nameserver your_DNS_server' >> /etc/resolv.confTesting and TroubleshootingOnce the necessary changes to
/etc/rc.conf are saved, a reboot can be
used to test the network configuration and to verify that the
system restarts without any configuration errors.
Alternatively, apply the settings to the networking system
with this command:&prompt.root; service netif restartIf a default gateway has been set in
/etc/rc.conf, also issue this
command:&prompt.root; service routing restartOnce the networking system has been relaunched, test the
NICs.Testing the Ethernet Cardnetwork cardstestingTo verify that an Ethernet card is configured correctly,
&man.ping.8; the interface itself, and then &man.ping.8;
another machine on the LAN:&prompt.user; ping -c5 192.168.1.3
PING 192.168.1.3 (192.168.1.3): 56 data bytes
64 bytes from 192.168.1.3: icmp_seq=0 ttl=64 time=0.082 ms
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.074 ms
64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.076 ms
64 bytes from 192.168.1.3: icmp_seq=3 ttl=64 time=0.108 ms
64 bytes from 192.168.1.3: icmp_seq=4 ttl=64 time=0.076 ms
--- 192.168.1.3 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.074/0.083/0.108/0.013 ms&prompt.user; ping -c5 192.168.1.2
PING 192.168.1.2 (192.168.1.2): 56 data bytes
64 bytes from 192.168.1.2: icmp_seq=0 ttl=64 time=0.726 ms
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.766 ms
64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.700 ms
64 bytes from 192.168.1.2: icmp_seq=3 ttl=64 time=0.747 ms
64 bytes from 192.168.1.2: icmp_seq=4 ttl=64 time=0.704 ms
--- 192.168.1.2 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.700/0.729/0.766/0.025 msTo test network resolution, use the host name instead
of the IP address. If there is no
DNS server on the network,
/etc/hosts must first be
configured.Troubleshootingnetwork cardstroubleshootingWhen troubleshooting hardware and software
configurations, check the simple things first. Is the
network cable plugged in? Are the network services properly
configured? Is the firewall configured correctly? Is the
NIC supported by &os;? Before sending
a bug report, always check the Hardware Notes, update the
version of &os; to the latest STABLE version, check the
mailing list archives, and search the Internet.If the card works, yet performance is poor, read
through &man.tuning.7;. Also, check the network
configuration as incorrect network settings can cause slow
connections.Some users experience one or two
device timeout messages, which is
normal for some cards. If they continue, or are bothersome,
determine if the device is conflicting with another device.
Double check the cable connections. Consider trying another
card.To resolve watchdog timeout
errors, first check the network cable. Many cards
require a PCI slot which supports bus
mastering. On some old motherboards, only one
PCI slot allows it, usually slot 0.
Check the NIC and the motherboard
documentation to determine if that may be the
problem.No route to host messages occur
if the system is unable to route a packet to the destination
host. This can happen if no default route is specified or
if a cable is unplugged. Check the output of
netstat -rn and make sure there is a
valid route to the host. If there is not, read
.ping: sendto: Permission denied
error messages are often caused by a misconfigured firewall.
If a firewall is enabled on &os; but no rules have been
defined, the default policy is to deny all traffic, even
&man.ping.8;. Refer to
for more information.Sometimes performance of the card is poor or below
average. In these cases, try setting the media
selection mode from autoselect to the
correct media selection. While this works for most
hardware, it may or may not resolve the issue. Again,
check all the network settings, and refer to
&man.tuning.7;.Virtual Hostsvirtual hostsIP
aliasesA common use of &os; is virtual site hosting, where one
server appears to the network as many servers. This is achieved
by assigning multiple network addresses to a single
interface.A given network interface has one real
address, and may have any number of alias
addresses. These aliases are normally added by placing alias
entries in /etc/rc.conf, as seen in this
example:ifconfig_fxp0_alias0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx"Alias entries must start with
alias0 using a
sequential number such as
alias0, alias1,
and so on. The configuration process will stop at the first
missing number.The calculation of alias netmasks is important. For a
given interface, there must be one address which correctly
represents the network's netmask. Any other addresses which
fall within this network must have a netmask of all
1s, expressed as either
255.255.255.255 or
0xffffffff.For example, consider the case where the
fxp0 interface is connected to two
networks: 10.1.1.0
with a netmask of
255.255.255.0 and
202.0.75.16 with a
netmask of
255.255.255.240. The
system is to be configured to appear in the ranges
10.1.1.1 through
10.1.1.5 and
202.0.75.17 through
202.0.75.20. Only
the first address in a given network range should have a real
netmask. All the rest
(10.1.1.2 through
10.1.1.5 and
202.0.75.18 through
202.0.75.20) must be
configured with a netmask of
255.255.255.255.The following /etc/rc.conf entries
configure the adapter correctly for this scenario:ifconfig_fxp0="inet 10.1.1.1 netmask 255.255.255.0"
ifconfig_fxp0_alias0="inet 10.1.1.2 netmask 255.255.255.255"
ifconfig_fxp0_alias1="inet 10.1.1.3 netmask 255.255.255.255"
ifconfig_fxp0_alias2="inet 10.1.1.4 netmask 255.255.255.255"
ifconfig_fxp0_alias3="inet 10.1.1.5 netmask 255.255.255.255"
ifconfig_fxp0_alias4="inet 202.0.75.17 netmask 255.255.255.240"
ifconfig_fxp0_alias5="inet 202.0.75.18 netmask 255.255.255.255"
ifconfig_fxp0_alias6="inet 202.0.75.19 netmask 255.255.255.255"
ifconfig_fxp0_alias7="inet 202.0.75.20 netmask 255.255.255.255"Configuring the System Logger,
syslogdNiclasZeisingContributed by system loggingsyslog&man.syslogd.8;System logging is an important aspect of system
administration. It is used to detect hardware and software
issues and errors in the system. It plays an important role
in security auditing and incident response. System daemons
without a controlling terminal usually log information to a
system logging facility or other log file.This section describes how to configure and use the &os;
system logger, &man.syslogd.8;, and how to perform log rotation
and log management using &man.newsyslog.8;. Focus will be on
setting up and using &man.syslogd.8; on a local machine. For
more advanced setups using a separate loghost, see
.Using syslogdIn the default &os; configuration, &man.syslogd.8; is
started at boot. This is controlled by the variable
syslogd_enable in
/etc/rc.conf. There are numerous
application arguments that affect the behavior of
&man.syslogd.8;. To change them, use
syslogd_flags in
/etc/rc.conf. Refer to &man.syslogd.8;
for more information on the arguments, and &man.rc.conf.5;,
and
for more information about
/etc/rc.conf and the &man.rc.8;
subsystem.Configuring syslogdsyslog.confThe configuration file, by default
/etc/syslog.conf, controls what
&man.syslogd.8; does with the log entries once they are
received. There are several parameters to control the
handling of incoming events, of which the most basic are
facility and
level. The facility describes
which subsystem generated the message, such as the kernel or a
daemon, and the level describes the severity of the event that
occurred. This makes it possible to log the message to
different log files, or discard it, depending on the facility
and level. It is also possible to take action depending on
the application that sent the message, and in the case of
remote logging, the hostname of the machine generating
the logging event.The configuration file for &man.syslogd.8; contains one
line per action, and the syntax for each line is a selector
field followed by an action field. The syntax of the selector
field is facility.level which will
match log messages from facility
at level level or higher. It is
also possible to add an optional comparison flag before the
level to specify more precisely what is logged. Multiple
selector fields can be used for the same action, and are
separated with a semicolon (;). Using
* will match everything. The action field
denotes where to send the log message, such as to a file or
remote log host. As an example, here is the default
syslog.conf from &os;:# $&os;$
#
# Spaces ARE valid field separators in this file. However,
# other *nix-like systems still insist on using tabs as field
# separators. If you are sharing this file between systems, you
# may want to use only tabs as field separators here.
# Consult the syslog.conf(5) manpage.
*.err;kern.warning;auth.notice;mail.crit /dev/console
*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err /var/log/messages
security.* /var/log/security
auth.info;authpriv.info /var/log/auth.log
mail.info /var/log/maillog
lpr.info /var/log/lpd-errs
ftp.info /var/log/xferlog
cron.* /var/log/cron
*.=debug /var/log/debug.log
*.emerg *
# uncomment this to log all writes to /dev/console to /var/log/console.log
#console.info /var/log/console.log
# uncomment this to enable logging of all log messages to /var/log/all.log
# touch /var/log/all.log and chmod it to mode 600 before it will work
#*.* /var/log/all.log
# uncomment this to enable logging to a remote loghost named loghost
#*.* @loghost
# uncomment these if you're running inn
# news.crit /var/log/news/news.crit
# news.err /var/log/news/news.err
# news.notice /var/log/news/news.notice
!ppp
*.* /var/log/ppp.log
!*Match all messages with a level of
err or higher, as well as
kern.warning,
auth.notice and
mail.crit, and send these log messages
to the console
(/dev/console).Match all messages from the mail
facility at level info or above, and
log the messages to
/var/log/maillog.This line uses a comparison flag, =
to only match messages at level debug,
and log them in
/var/log/debug.log.Here is an example usage of a program
specification. This makes the rules
following it only valid for the program in the program
specification. In this case, this and the following
lines log all messages from &man.ppp.8;, but no other
programs, to
/var/log/ppp.log.This example shows that there are plenty of levels and
subsystems. The levels are, in order from most to least
critical: emerg, alert,
crit, err,
warning, notice,
info, and debug.The facilities are, in no particular order:
auth, authpriv,
console, cron,
daemon, ftp,
kern, lpr,
mail, mark,
news, security,
syslog, user,
uucp, and local0 through
local7. Be aware that other operating
systems might have different facilities.With this knowledge, it is easy to add a new line to
/etc/syslog.conf to log everything from
the different daemons on level notice and
higher to /var/log/daemon.log. Just add
the following:daemon.notice /var/log/daemon.logFor more information about the different levels and
facilities, refer to &man.syslog.3; and &man.syslogd.8;.
For more information about
/etc/syslog.conf, its syntax, and more
advanced usage examples, see &man.syslog.conf.5; and
.Log Management and Rotation with
newsyslognewsyslognewsyslog.conflog rotationlog managementLog files tend to grow quickly and accumulate steadily.
This leads to the files being full of less immediately useful
information while filling up the hard drive. Log management
attempts to mitigate this. In &os;, &man.newsyslog.8; is used
to manage log files. This program periodically rotates and
compresses log files, and optionally creates missing log files
and signals programs when log files are moved. The log files
are not necessarily generated by &man.syslogd.8; as
&man.newsyslog.8; works with any logs written from any
program. While &man.newsyslog.8; is normally run from
&man.cron.8;, it is not a system daemon. In the default
configuration, it is run every hour.Configuring
newsyslogTo know which actions to take, &man.newsyslog.8; reads
its configuration file, by default
/etc/newsyslog.conf. This
configuration file contains one line for each file that
&man.newsyslog.8; manages. Each line states the file
owner, permissions, when to rotate that file, optional flags
that affect log rotation, such as compression, and programs
to signal when the log is rotated. Here is the default
configuration in &os;:# configuration file for newsyslog
# $FreeBSD$
#
# Entries which do not specify the '/pid_file' field will cause the
# syslogd process to be signalled when that log file is rotated. This
# action is only appropriate for log files which are written to by the
# syslogd process (ie, files listed in /etc/syslog.conf). If there
# is no process which needs to be signalled when a given log file is
# rotated, then the entry for that file should include the 'N' flag.
#
# The 'flags' field is one or more of the letters: BCDGJNUXZ or a '-'.
#
# Note: some sites will want to select more restrictive protections than the
# defaults. In particular, it may be desirable to switch many of the 644
# entries to 640 or 600. For example, some sites will consider the
# contents of maillog, messages, and lpd-errs to be confidential. In the
# future, these defaults may change to more conservative ones.
#
# logfilename [owner:group] mode count size when flags [/pid_file] [sig_num]
/var/log/all.log 600 7 * @T00 J
/var/log/amd.log 644 7 100 * J
/var/log/auth.log 600 7 100 @0101T JC
/var/log/console.log 600 5 100 * J
/var/log/cron 600 3 100 * JC
/var/log/daily.log 640 7 * @T00 JN
/var/log/debug.log 600 7 100 * JC
/var/log/kerberos.log 600 7 100 * J
/var/log/lpd-errs 644 7 100 * JC
/var/log/maillog 640 7 * @T00 JC
/var/log/messages 644 5 100 @0101T JC
/var/log/monthly.log 640 12 * $M1D0 JN
/var/log/pflog 600 3 100 * JB /var/run/pflogd.pid
/var/log/ppp.log root:network 640 3 100 * JC
/var/log/security 600 10 100 * JC
/var/log/sendmail.st 640 10 * 168 B
/var/log/utx.log 644 3 * @01T05 B
/var/log/weekly.log 640 5 1 $W6D0 JN
/var/log/xferlog 600 7 100 * JCEach line starts with the name of the file to be
rotated, optionally followed by an owner and group for both
rotated and newly created files. The
mode field sets the permissions on the
log file and count denotes how many
rotated log files should be kept. The
size and when fields
tell &man.newsyslog.8; when to rotate the file. A log
file is rotated when either its size is larger than the
size field, or when the time in the
when filed has passed.
* means that this field is ignored. The
flags field gives
&man.newsyslog.8; further instructions, such as how to
compress the rotated file or to create the log file if it
is missing. The last two fields are optional, and
specify the
PID file of a
process and a signal number to send to that process when the
file is rotated. For more information on all fields, valid
flags, and how to specify the rotation time, refer to
&man.newsyslog.conf.5;. Since &man.newsyslog.8; is run from
&man.cron.8;, it can not rotate files more often than it is
run from &man.cron.8;.Configuration Files/etc
LayoutThere are a number of directories in which configuration
information is kept. These include:/etcGeneric system-specific configuration
information./etc/defaultsDefault versions of system configuration
files./etc/mailExtra &man.sendmail.8; configuration and other
MTA configuration files./etc/pppConfiguration for both user- and kernel-ppp
programs./etc/namedbDefault location for &man.named.8; data.
Normally named.conf and zone
files are stored here./usr/local/etcConfiguration files for installed applications.
May contain per-application subdirectories./usr/local/etc/rc.d&man.rc.8; scripts for installed
applications./var/dbAutomatically generated system-specific database
files, such as the package database and the
&man.locate.1; database.HostnameshostnameDNS/etc/resolv.confresolv.confHow a &os; system accesses the Internet Domain Name
System (DNS) is controlled by
&man.resolv.conf.5;.The most common entries to
/etc/resolv.conf are:nameserverThe IP address of a name
server the resolver should query. The servers are
queried in the order listed with a maximum of
three.searchSearch list for hostname lookup. This is
normally determined by the domain of the local
hostname.domainThe local domain name.A typical /etc/resolv.conf looks
like this:search example.com
nameserver 147.11.1.11
nameserver 147.11.100.30Only one of the search and
domain options should be used.When using DHCP, &man.dhclient.8;
usually rewrites /etc/resolv.conf
with information received from the DHCP
server./etc/hostshosts/etc/hosts is a simple text
database which works in conjunction with
DNS and
NIS to provide host name to
IP address mappings. Entries for local
computers connected via a LAN can be
added to this file for simplistic naming purposes instead
of setting up a &man.named.8; server. Additionally,
/etc/hosts can be used to provide a
local record of Internet names, reducing the need to query
external DNS servers for commonly
accessed names.# $&os;$
#
#
# Host Database
#
# This file should contain the addresses and aliases for local hosts that
# share this file. Replace 'my.domain' below with the domainname of your
# machine.
#
# In the presence of the domain name service or NIS, this file may
# not be consulted at all; see /etc/nsswitch.conf for the resolution order.
#
#
::1 localhost localhost.my.domain
127.0.0.1 localhost localhost.my.domain
#
# Imaginary network.
#10.0.0.2 myname.my.domain myname
#10.0.0.3 myfriend.my.domain myfriend
#
# According to RFC 1918, you can use the following IP networks for
# private nets which will never be connected to the Internet:
#
# 10.0.0.0 - 10.255.255.255
# 172.16.0.0 - 172.31.255.255
# 192.168.0.0 - 192.168.255.255
#
# In case you want to be able to connect to the Internet, you need
# real official assigned numbers. Do not try to invent your own network
# numbers but instead get one from your network provider (if any) or
# from your regional registry (ARIN, APNIC, LACNIC, RIPE NCC, or AfriNIC.)
#The format of /etc/hosts is as
follows:[Internet address] [official hostname] [alias1] [alias2] ...For example:10.0.0.1 myRealHostname.example.com myRealHostname foobar1 foobar2Consult &man.hosts.5; for more information.Tuning with &man.sysctl.8;sysctltuningwith sysctl&man.sysctl.8; is used to make changes to a running &os;
system. This includes many advanced options of the
TCP/IP stack and virtual memory system
that can dramatically improve performance for an experienced
system administrator. Over five hundred system variables can
be read and set using &man.sysctl.8;.At its core, &man.sysctl.8; serves two functions: to read
and to modify system settings.To view all readable variables:&prompt.user; sysctl -aTo read a particular variable, specify its name:&prompt.user; sysctl kern.maxproc
kern.maxproc: 1044To set a particular variable, use the
variable=value
syntax:&prompt.root; sysctl kern.maxfiles=5000
kern.maxfiles: 2088 -> 5000Settings of sysctl variables are usually either strings,
numbers, or booleans, where a boolean is 1
for yes or 0 for no.To automatically set some variables each time the machine
boots, add them to /etc/sysctl.conf. For
more information, refer to &man.sysctl.conf.5; and
.sysctl.confsysctl.confsysctlThe configuration file for &man.sysctl.8;,
/etc/sysctl.conf, looks much like
/etc/rc.conf. Values are set in a
variable=value form. The specified values
are set after the system goes into multi-user mode. Not all
variables are settable in this mode.For example, to turn off logging of fatal signal exits
and prevent users from seeing processes started by other
users, the following tunables can be set in
/etc/sysctl.conf:# Do not log fatal signal exits (e.g., sig 11)
kern.logsigexit=0
# Prevent users from seeing information about processes that
# are being run under another UID.
security.bsd.see_other_uids=0&man.sysctl.8; Read-onlyTomRhodesContributed by In some cases it may be desirable to modify read-only
&man.sysctl.8; values, which will require a reboot of the
system.For instance, on some laptop models the &man.cardbus.4;
device will not probe memory ranges and will fail with errors
similar to:cbb0: Could not map register memory
device_probe_and_attach: cbb0 attach returned 12The fix requires the modification of a read-only
&man.sysctl.8; setting. Add
to
/boot/loader.conf and reboot. Now
&man.cardbus.4; should work properly.Tuning DisksThe following section will discuss various tuning
mechanisms and options which may be applied to disk
devices. In many cases, disks with mechanical parts,
such as SCSI drives, will be the
bottleneck driving down the overall system performance. While
a solution is to install a drive without mechanical parts,
such as a solid state drive, mechanical drives are not
going away anytime in the near future. When tuning disks,
it is advisable to utilize the features of the &man.iostat.8;
command to test various changes to the system. This
command will allow the user to obtain valuable information
on system IO.Sysctl Variablesvfs.vmiodirenablevfs.vmiodirenableThe vfs.vmiodirenable &man.sysctl.8;
variable
may be set to either 0 (off) or
1 (on). It is set to
1 by default. This variable controls
how directories are cached by the system. Most directories
are small, using just a single fragment (typically 1 K)
in the file system and typically 512 bytes in the
buffer cache. With this variable turned off, the buffer
cache will only cache a fixed number of directories, even
if the system has a huge amount of memory. When turned on,
this &man.sysctl.8; allows the buffer cache to use the
VM page cache to cache the directories,
making all the memory available for caching directories.
However, the minimum in-core memory used to cache a
directory is the physical page size (typically 4 K)
rather than 512 bytes. Keeping this option enabled
is recommended if the system is running any services which
manipulate large numbers of files. Such services can
include web caches, large mail systems, and news systems.
Keeping this option on will generally not reduce
performance, even with the wasted memory, but one should
experiment to find out.vfs.write_behindvfs.write_behindThe vfs.write_behind &man.sysctl.8;
variable
defaults to 1 (on). This tells the file
system to issue media writes as full clusters are collected,
which typically occurs when writing large sequential files.
This avoids saturating the buffer cache with dirty buffers
when it would not benefit I/O performance. However, this
may stall processes and under certain circumstances should
be turned off.vfs.hirunningspacevfs.hirunningspaceThe vfs.hirunningspace &man.sysctl.8;
variable determines how much outstanding write I/O may be
queued to disk controllers system-wide at any given
instance. The default is usually sufficient, but on
machines with many disks, try bumping it up to four or five
megabytes. Setting too high a value
which exceeds the buffer cache's write threshold can lead
to bad clustering performance. Do not set this value
arbitrarily high as higher write values may add latency to
reads occurring at the same time.There are various other buffer cache and
VM page cache related &man.sysctl.8;
values. Modifying these values is not recommended as the
VM system does a good job of
automatically tuning itself.vm.swap_idle_enabledvm.swap_idle_enabledThe vm.swap_idle_enabled
&man.sysctl.8; variable is useful in large multi-user
systems with many active login users and lots of idle
processes. Such systems tend to generate continuous
pressure on free memory reserves. Turning this feature on
and tweaking the swapout hysteresis (in idle seconds) via
vm.swap_idle_threshold1 and
vm.swap_idle_threshold2 depresses the
priority of memory pages associated with idle processes more
quickly then the normal pageout algorithm. This gives a
helping hand to the pageout daemon. Only turn this option
on if needed, because the tradeoff is essentially pre-page
memory sooner rather than later which eats more swap and
disk bandwidth. In a small system this option will have a
determinable effect, but in a large system that is already
doing moderate paging, this option allows the
VM system to stage whole processes into
and out of memory easily.hw.ata.wchw.ata.wcTurning off IDE write caching reduces
write bandwidth to IDE disks, but may
sometimes be necessary due to data consistency issues
introduced by hard drive vendors. The problem is that
some IDE drives lie about when a write
completes. With IDE write caching
turned on, IDE hard drives write data
to disk out of order and will sometimes delay writing some
blocks indefinitely when under heavy disk load. A crash or
power failure may cause serious file system corruption.
Check the default on the system by observing the
hw.ata.wc &man.sysctl.8; variable. If
IDE write caching is turned off, one can
set this read-only variable to
1 in
/boot/loader.conf in order to enable
it at boot time.For more information, refer to &man.ata.4;.SCSI_DELAY
(kern.cam.scsi_delay)kern.cam.scsi_delaykernel optionsSCSI DELAYThe SCSI_DELAY kernel configuration
option may be used to reduce system boot times. The
defaults are fairly high and can be responsible for
15 seconds of delay in the boot process.
Reducing it to 5 seconds usually works
with modern drives. The
kern.cam.scsi_delay boot time tunable
should be used. The tunable and kernel configuration
option accept values in terms of
milliseconds and
notseconds.Soft UpdatesSoft Updates&man.tunefs.8;To fine-tune a file system, use &man.tunefs.8;. This
program has many different options. To toggle Soft Updates
on and off, use:&prompt.root; tunefs -n enable /filesystem
&prompt.root; tunefs -n disable /filesystemA file system cannot be modified with &man.tunefs.8; while
it is mounted. A good time to enable Soft Updates is before
any partitions have been mounted, in single-user mode.Soft Updates is recommended for UFS
file systems as it drastically improves meta-data performance,
mainly file creation and deletion, through the use of a memory
cache. There are two downsides to Soft Updates to be aware
of. First, Soft Updates guarantee file system consistency
in the case of a crash, but could easily be several seconds
or even a minute behind updating the physical disk. If the
system crashes, unwritten data may be lost. Secondly, Soft
Updates delay the freeing of file system blocks. If the
root file system is almost full, performing a major update,
such as make installworld, can cause the
file system to run out of space and the update to fail.More Details About Soft UpdatesSoft UpdatesdetailsMeta-data updates are updates to non-content data like
inodes or directories. There are two traditional approaches
to writing a file system's meta-data back to disk.Historically, the default behavior was to write out
meta-data updates synchronously. If a directory changed,
the system waited until the change was actually written to
disk. The file data buffers (file contents) were passed
through the buffer cache and backed up to disk later on
asynchronously. The advantage of this implementation is
that it operates safely. If there is a failure during an
update, meta-data is always in a consistent state. A
file is either created completely or not at all. If the
data blocks of a file did not find their way out of the
buffer cache onto the disk by the time of the crash,
&man.fsck.8; recognizes this and repairs the file system
by setting the file length to 0.
Additionally, the implementation is clear and simple. The
disadvantage is that meta-data changes are slow. For
example, rm -r touches all the files in a
directory sequentially, but each directory change will be
written synchronously to the disk. This includes updates to
the directory itself, to the inode table, and possibly to
indirect blocks allocated by the file. Similar
considerations apply for unrolling large hierarchies using
tar -x.The second approach is to use asynchronous meta-data
updates. This is the default for a UFS
file system mounted with mount -o async.
Since all meta-data updates are also passed through the
buffer cache, they will be intermixed with the updates of
the file content data. The advantage of this
implementation is there is no need to wait until each
meta-data update has been written to disk, so all operations
which cause huge amounts of meta-data updates work much
faster than in the synchronous case. This implementation
is still clear and simple, so there is a low risk for bugs
creeping into the code. The disadvantage is that there is
no guarantee for a consistent state of the file system.
If there is a failure during an operation that updated
large amounts of meta-data, like a power failure or someone
pressing the reset button, the file system will be left
in an unpredictable state. There is no opportunity to
examine the state of the file system when the system comes
up again as the data blocks of a file could already have
been written to the disk while the updates of the inode
table or the associated directory were not. It is
impossible to implement a &man.fsck.8; which is able to
clean up the resulting chaos because the necessary
information is not available on the disk. If the file
system has been damaged beyond repair, the only choice
is to reformat it and restore from backup.The usual solution for this problem is to implement
dirty region logging, which is also
referred to as journaling.
Meta-data updates are still written synchronously, but only
into a small region of the disk. Later on, they are moved
to their proper location. Because the logging area is a
small, contiguous region on the disk, there are no long
distances for the disk heads to move, even during heavy
operations, so these operations are quicker than synchronous
updates. Additionally, the complexity of the implementation
is limited, so the risk of bugs being present is low. A
disadvantage is that all meta-data is written twice, once
into the logging region and once to the proper location, so
performance pessimization might result. On
the other hand, in case of a crash, all pending meta-data
operations can be either quickly rolled back or completed
from the logging area after the system comes up again,
resulting in a fast file system startup.Kirk McKusick, the developer of Berkeley
FFS, solved this problem with Soft
Updates. All pending meta-data updates are kept in memory
and written out to disk in a sorted sequence
(ordered meta-data updates). This has the
effect that, in case of heavy meta-data operations, later
updates to an item catch the earlier ones
which are still in memory and have not already been written
to disk. All operations are generally performed in memory
before the update is written to disk and the data blocks are
sorted according to their position so that they will not be
on the disk ahead of their meta-data. If the system
crashes, an implicit log rewind causes all
operations which were not written to the disk appear as if
they never happened. A consistent file system state is
maintained that appears to be the one of 30 to 60 seconds
earlier. The algorithm used guarantees that all resources
in use are marked as such in their blocks and inodes.
After a crash, the only resource allocation error that
occurs is that resources are marked as used
which are actually free. &man.fsck.8;
recognizes this situation, and frees the resources that
are no longer used. It is safe to ignore the dirty state
of the file system after a crash by forcibly mounting it
with mount -f. In order to free
resources that may be unused, &man.fsck.8; needs to be run
at a later time. This is the idea behind the
background &man.fsck.8;: at system
startup time, only a snapshot of the
file system is recorded and &man.fsck.8; is run afterwards.
All file systems can then be mounted
dirty, so the system startup proceeds in
multi-user mode. Then, background &man.fsck.8; is
scheduled for all file systems where this is required, to
free resources that may be unused. File systems that do
not use Soft Updates still need the usual foreground
&man.fsck.8;.The advantage is that meta-data operations are nearly
as fast as asynchronous updates and are faster than
logging, which has to write the
meta-data twice. The disadvantages are the complexity of
the code, a higher memory consumption, and some
idiosyncrasies. After a crash, the state of the file
system appears to be somewhat older. In
situations where the standard synchronous approach would
have caused some zero-length files to remain after the
&man.fsck.8;, these files do not exist at all with Soft
Updates because neither the meta-data nor the file contents
have been written to disk. Disk space is not released until
the updates have been written to disk, which may take place
some time after running &man.rm.1;. This may cause problems
when installing large amounts of data on a file system
that does not have enough free space to hold all the files
twice.Tuning Kernel Limitstuningkernel limitsFile/Process Limitskern.maxfileskern.maxfilesThe kern.maxfiles &man.sysctl.8;
variable can be raised or lowered based upon system
requirements. This variable indicates the maximum number
of file descriptors on the system. When the file descriptor
table is full, file: table is full
will show up repeatedly in the system message buffer, which
can be viewed using &man.dmesg.8;.Each open file, socket, or fifo uses one file
descriptor. A large-scale production server may easily
require many thousands of file descriptors, depending on the
kind and number of services running concurrently.In older &os; releases, the default value of
kern.maxfiles is derived from
in the kernel configuration file.
kern.maxfiles grows proportionally to the
value of . When compiling a custom
kernel, consider setting this kernel configuration option
according to the use of the system. From this number, the
kernel is given most of its pre-defined limits. Even though
a production machine may not have 256 concurrent users, the
resources needed may be similar to a high-scale web
server.The read-only &man.sysctl.8; variable
kern.maxusers is automatically sized at
boot based on the amount of memory available in the system,
and may be determined at run-time by inspecting the value
of kern.maxusers. Some systems require
larger or smaller values of
kern.maxusers and values of
64, 128, and
256 are not uncommon. Going above
256 is not recommended unless a huge
number of file descriptors is needed. Many of the tunable
values set to their defaults by
kern.maxusers may be individually
overridden at boot-time or run-time in
/boot/loader.conf. Refer to
&man.loader.conf.5; and
/boot/defaults/loader.conf for more
details and some hints.In older releases, the system will auto-tune
maxusers if it is set to
0.
The auto-tuning algorithm sets
maxusers equal to the amount of
memory in the system, with a minimum of
32, and a maximum of
384.. When
setting this option, set maxusers to
at least 4, especially if the system
runs &xorg; or is used to
compile software. The most important table set by
maxusers is the maximum number of
processes, which is set to
20 + 16 * maxusers. If
maxusers is set to 1,
there can only be
36 simultaneous processes, including
the 18 or so that the system starts up
at boot time and the 15 or so used by
&xorg;. Even a simple task like
reading a manual page will start up nine processes to
filter, decompress, and view it. Setting
maxusers to 64 allows
up to 1044 simultaneous processes, which
should be enough for nearly all uses. If, however, the
proc table full error is displayed
when trying to start another program, or a server is
running with a large number of simultaneous users, increase
the number and rebuild.maxusers does
not limit the number of users which
can log into the machine. It instead sets various table
sizes to reasonable values considering the maximum number
of users on the system and how many processes each user
will be running.kern.ipc.somaxconnkern.ipc.somaxconnThe kern.ipc.somaxconn &man.sysctl.8;
variable limits the size of the listen queue for accepting
new TCP connections. The default value
of 128 is typically too low for robust
handling of new connections on a heavily loaded web server.
For such environments, it is recommended to increase this
value to 1024 or higher. A service
such as &man.sendmail.8;, or
Apache may itself limit the
listen queue size, but will often have a directive in its
configuration file to adjust the queue size. Large listen
queues do a better job of avoiding Denial of Service
(DoS) attacks.Network LimitsThe NMBCLUSTERS kernel configuration
option dictates the amount of network Mbufs available to the
system. A heavily-trafficked server with a low number of
Mbufs will hinder performance. Each cluster represents
approximately 2 K of memory, so a value of
1024 represents 2
megabytes of kernel memory reserved for network buffers. A
simple calculation can be done to figure out how many are
needed. A web server which maxes out at
1000 simultaneous connections where each
connection uses a 6 K receive and 16 K send buffer,
requires approximately 32 MB worth of network buffers
to cover the web server. A good rule of thumb is to multiply
by 2, so
2x32 MB / 2 KB =
64 MB / 2 kB =
32768. Values between
4096 and 32768 are
recommended for machines with greater amounts of memory.
Never specify an arbitrarily high value for this parameter
as it could lead to a boot time crash. To observe network
cluster usage, use with
&man.netstat.1;.The kern.ipc.nmbclusters loader tunable
should be used to tune this at boot time. Only older versions
of &os; will require the use of the
NMBCLUSTERS kernel &man.config.8;
option.For busy servers that make extensive use of the
&man.sendfile.2; system call, it may be necessary to increase
the number of &man.sendfile.2; buffers via the
NSFBUFS kernel configuration option or by
setting its value in /boot/loader.conf
(see &man.loader.8; for details). A common indicator that
this parameter needs to be adjusted is when processes are seen
in the sfbufa state. The &man.sysctl.8;
variable kern.ipc.nsfbufs is read-only.
This parameter nominally scales with
kern.maxusers, however it may be necessary
to tune accordingly.Even though a socket has been marked as non-blocking,
calling &man.sendfile.2; on the non-blocking socket may
result in the &man.sendfile.2; call blocking until enough
struct sf_buf's are made
available.net.inet.ip.portrange.*net.inet.ip.portrange.*The net.inet.ip.portrange.*
&man.sysctl.8; variables control the port number ranges
automatically bound to TCP and
UDP sockets. There are three ranges: a
low range, a default range, and a high range. Most network
programs use the default range which is controlled by
net.inet.ip.portrange.first and
net.inet.ip.portrange.last, which default
to 1024 and 5000,
respectively. Bound port ranges are used for outgoing
connections and it is possible to run the system out of
ports under certain circumstances. This most commonly
occurs when running a heavily loaded web proxy. The port
range is not an issue when running a server which handles
mainly incoming connections, such as a web server, or has
a limited number of outgoing connections, such as a mail
relay. For situations where there is a shortage of ports,
it is recommended to increase
net.inet.ip.portrange.last modestly. A
value of 10000, 20000
or 30000 may be reasonable. Consider
firewall effects when changing the port range. Some
firewalls may block large ranges of ports, usually
low-numbered ports, and expect systems to use higher ranges
of ports for outgoing connections. For this reason, it
is not recommended that the value of
net.inet.ip.portrange.first be
lowered.TCP Bandwidth Delay ProductTCP Bandwidth Delay Product
Limitingnet.inet.tcp.inflight.enableTCP bandwidth delay product limiting
can be enabled by setting the
net.inet.tcp.inflight.enable
&man.sysctl.8; variable to 1. This
instructs the system to attempt to calculate the bandwidth
delay product for each connection and limit the amount of
data queued to the network to just the amount required to
maintain optimum throughput.This feature is useful when serving data over modems,
Gigabit Ethernet, high speed WAN links,
or any other link with a high bandwidth delay product,
especially when also using window scaling or when a large
send window has been configured. When enabling this option,
also set net.inet.tcp.inflight.debug to
0 to disable debugging. For production
use, setting net.inet.tcp.inflight.min
to at least 6144 may be beneficial.
Setting high minimums may effectively disable bandwidth
limiting, depending on the link. The limiting feature
reduces the amount of data built up in intermediate route
and switch packet queues and reduces the amount of data
built up in the local host's interface queue. With fewer
queued packets, interactive connections, especially over
slow modems, will operate with lower
Round Trip Times. This feature only
effects server side data transmission such as uploading.
It has no effect on data reception or downloading.Adjusting net.inet.tcp.inflight.stab
is not recommended. This parameter
defaults to 20, representing 2 maximal
packets added to the bandwidth delay product window
calculation. The additional window is required to stabilize
the algorithm and improve responsiveness to changing
conditions, but it can also result in higher &man.ping.8;
times over slow links, though still much lower than without
the inflight algorithm. In such cases, try reducing this
parameter to 15, 10,
or 5 and reducing
net.inet.tcp.inflight.min to a value such
as 3500 to get the desired effect.
Reducing these parameters should be done as a last resort
only.Virtual Memorykern.maxvnodesA vnode is the internal representation of a file or
directory. Increasing the number of vnodes available to
the operating system reduces disk I/O. Normally, this is
handled by the operating system and does not need to be
changed. In some cases where disk I/O is a bottleneck and
the system is running out of vnodes, this setting needs
to be increased. The amount of inactive and free
RAM will need to be taken into
account.To see the current number of vnodes in use:&prompt.root; sysctl vfs.numvnodes
vfs.numvnodes: 91349To see the maximum vnodes:&prompt.root; sysctl kern.maxvnodes
kern.maxvnodes: 100000If the current vnode usage is near the maximum, try
increasing kern.maxvnodes by a value of
1000. Keep an eye on the number of
vfs.numvnodes. If it climbs up to the
maximum again, kern.maxvnodes will need
to be increased further. Otherwise, a shift in memory
usage as reported by &man.top.1; should be visible and
more memory should be active.Adding Swap SpaceSometimes a system requires more swap space. There are
three ways to increase swap space: add a new hard drive,
enable swap over NFS, or create a swap file
on an existing partition.For information on how to encrypt swap space, which options
exist, and why it should be done, refer to
.Swap on a New or Existing Hard DriveAdding a new hard drive for swap gives better performance
than adding a partition on an existing drive. Setting up
partitions and hard drives is explained in
while
discusses partition
layouts and swap partition size considerations.Use &man.swapon.8; to add a swap partition to the system.
For example:&prompt.root; swapon /dev/ada1s1bIt is possible to use any partition not currently
mounted, even if it already contains data. Using
&man.swapon.8; on a partition that contains data will
overwrite and destroy that data. Make sure that the
partition to be added as swap is really the intended
partition before running &man.swapon.8;.To automatically add this swap partition on boot, add an
entry to /etc/fstab:/dev/ada1s1b none swap sw 0 0See &man.fstab.5; for an explanation of the entries in
/etc/fstab.Swapping over NFSSwapping over NFS is only recommended
when there is no local hard disk to swap to.
NFS swapping will be limited by the
available network bandwidth and puts an additional burden
on &man.nfsd.8;.SwapfilesTo create a swap file, specify its size. The following
example creates a 64MB file named
/usr/swap0.Creating a Swapfile on &os;The GENERIC kernel already
includes the memory disk driver (&man.md.4;) required
for this operation. When building a custom kernel,
make sure to include the following line in the custom
configuration file:device mdFor information on building a custom kernel, refer
to .First, create the swapfile
/usr/swap0:&prompt.root; dd if=/dev/zero of=/usr/swap0 bs=1024k count=64Then, set proper permissions on
/usr/swap0:&prompt.root; chmod 0600 /usr/swap0Enable the swap file in
/etc/rc.conf:swapfile="/usr/swap0" # Set to name of swapfile if aux swapfile desired.Reboot the machine or, to enable the swap file
immediately, type:&prompt.root; mdconfig -a -t vnode -f /usr/swap0 -u 0 && swapon /dev/md0Power and Resource ManagementHitenPandyaWritten by TomRhodesIt is important to utilize hardware resources in an
efficient manner. Before the Advanced Configuration and Power
Interface (ACPI) was introduced, it was
difficult and inflexible for operating systems to manage the
power usage and thermal properties of a system. The hardware
was managed by the BIOS and the user had less
control and visibility into the power management settings. Some
limited configurability was available via Advanced
Power Management (APM). Power
and resource management allows the operating system to monitor
system limits and to possibly provide an alert if the system
temperature increases unexpectedly.This section provides comprehensive information about
ACPI. References will be provided for
further reading.What Is ACPI?ACPIAPMACPI is a standard written by an
alliance of vendors to provide a standard interface for
hardware resources and power management. It is a key
element in Operating System-directed configuration
and Power Management as it provides more control
and flexibility to the operating system. Modern systems
stretched the limits of the current Plug and
Play interfaces prior to the introduction of
ACPI. ACPI is the
direct successor to APM.Shortcomings of Advanced Power ManagementThe APM facility controls the power
usage of a system based on its activity. The
APM BIOS is supplied
by the vendor and is specific to the hardware platform. An
APM driver in the operating system
mediates access to the APM
Software Interface, which allows management of
power levels. APM should still be used
for systems manufactured at or before the year 2000.There are four major problems in APM.
First, power management is done by the vendor-specific
BIOS, separate from the operating system.
For example, the user can set idle-time values for a hard
drive in the APM BIOS
so that, when exceeded, the BIOS spins
down the hard drive without the consent of the operating
system. Second, the APM logic is embedded
in the BIOS, and it operates outside the
scope of the operating system. This means that users can
only fix problems in the APM
BIOS by flashing a new one into the
ROM, which is a dangerous procedure with
the potential to leave the system in an unrecoverable state
if it fails. Third, APM is a
vendor-specific technology, meaning that there is a lot of
duplication of efforts and bugs found in one vendor's
BIOS may not be solved in others. Lastly,
the APM BIOS did not
have enough room to implement a sophisticated power policy
or one that can adapt well to the purpose of the
machine.The Plug and Play BIOS
(PNPBIOS) was unreliable in
many situations. PNPBIOS is 16-bit
technology, so the operating system has to use 16-bit
emulation in order to interface with
PNPBIOS methods.The &os; APM driver is documented in
&man.apm.4;.Configuring ACPIThe &man.acpi.4; driver is loaded by default at start
up by &man.loader.8; and should
not be compiled into the kernel. The
reasoning is that modules are easier to work with and do not
require a kernel rebuild. This has the advantage of making
testing easier. Another reason is that starting
ACPI after a system has been brought up
often does not work well. If experiencing problems,
ACPI can be disabled altogether. This
driver should not and can not be unloaded because the system
bus uses it for various hardware interactions.
ACPI can be disabled by rebooting after
setting hint.acpi.0.disabled="1" in
/boot/loader.conf or by setting this
variable at the &man.loader.8; prompt.ACPI and APM
cannot coexist and should be used separately. The last one
to load will terminate if the driver notices the other is
running.ACPI can be used to put the system into
a sleep mode with &man.acpiconf.8;, the
flag, and a 1-5 option. Most users
only need 1 (quick suspend to
RAM) or 3 (suspend to
RAM). Option 5 performs
a soft-off which is the same action as:&prompt.root; halt -pOther options are available via &man.sysctl.8;. Refer to
&man.acpi.4; and &man.acpiconf.8; for more information.Using and Debugging &os; ACPINateLawsonWritten by PeterSchultzWith contributions from TomRhodesACPIproblemsACPI is a fundamentally new way of
discovering devices, managing power usage, and providing
standardized access to various hardware previously managed by
the BIOS. Progress is being made toward
ACPI working on all systems, but bugs in some
motherboards' ACPI Machine
Language (AML) bytecode,
incompleteness in &os;'s kernel subsystems, and bugs in the
&intel; ACPI-CA interpreter continue to
appear.This section is intended to help users assist the &os;
ACPI maintainers in identifying the root
cause of problems and in debugging and developing a
solution.Submitting Debugging InformationBefore submitting a problem, ensure the latest
BIOS version is installed and, if
available, the embedded controller firmware version.When submitting a problem, send the following information
to
freebsd-acpi@FreeBSD.org:Description of the buggy behavior, including system
type and model and anything that causes the bug to appear.
Note as accurately as possible when the bug began
occurring if it is new.The output of &man.dmesg.8; after running
boot -v, including any error messages
generated by the bug.The &man.dmesg.8; output from boot
-v with ACPI disabled,
if disabling it helps to fix the problem.Output from sysctl hw.acpi. This
lists which features the system offers.The URL to a pasted version of the
ACPI Source
Language (ASL). Do
not send the
ASL directly to the list as it can be
very large. Generate a copy of the
ASL by running this command:&prompt.root; acpidump -dt > name-system.aslSubstitute the login name for
name and manufacturer/model for
system. For example, use
njl-FooCo6000.asl.Most &os; developers watch &a.current;, but one should
submit problems to &a.acpi.name; to be sure it is seen. Be
patient when waiting for a response. If the bug is not
immediately apparent, submit a PR using
&man.send-pr.1;. When entering a PR,
include the same information as requested above. This helps
developers to track the problem and resolve it. Do not send a
PR without emailing &a.acpi.name; first as
it is likely that the problem has been reported before.BackgroundACPIACPI is present in all modern computers
that conform to the ia32 (x86), ia64 (Itanium), and amd64
(AMD) architectures. The full standard has many features
including CPU performance management, power
planes control, thermal zones, various battery systems,
embedded controllers, and bus enumeration. Most systems
implement less than the full standard. For instance, a
desktop system usually only implements bus enumeration
while a laptop might have cooling and battery management
support as well. Laptops also have suspend and resume, with
their own associated complexity.An ACPI-compliant system has various
components. The BIOS and chipset vendors
provide various fixed tables, such as FADT,
in memory that specify things like the APIC
map (used for SMP), config registers, and
simple configuration values. Additionally, a bytecode table,
the Differentiated System Description
Table DSDT, specifies a
tree-like name space of devices and methods.The ACPI driver must parse the fixed
tables, implement an interpreter for the bytecode, and modify
device drivers and the kernel to accept information from the
ACPI subsystem. For &os;, &intel; has
provided an interpreter (ACPI-CA) that is
shared with &linux; and NetBSD. The path to the
ACPI-CA source code is
src/sys/contrib/dev/acpica. The glue
code that allows ACPI-CA to work on &os; is
in src/sys/dev/acpica/Osd. Finally,
drivers that implement various ACPI devices
are found in src/sys/dev/acpica.Common ProblemsACPIproblemsFor ACPI to work correctly, all the
parts have to work correctly. Here are some common problems,
in order of frequency of appearance, and some possible
workarounds or fixes.Mouse IssuesIn some cases, resuming from a suspend operation will
cause the mouse to fail. A known work around is to add
hint.psm.0.flags="0x3000" to
/boot/loader.conf. If this does not
work, consider sending a bug report using
&man.send-pr.1;.Suspend/ResumeACPI has three suspend to
RAM (STR) states,
S1-S3, and one suspend
to disk state (STD), called
S4. S5 is
soft off and is the normal state the system
is in when plugged in but not powered up.
S4 can be implemented in two separate
ways. S4BIOS is a
BIOS-assisted suspend to disk.
S4OS is implemented
entirely by the operating system.Start by checking sysctl hw.acpi
for the suspend-related items. Here are the results for a
Thinkpad:hw.acpi.supported_sleep_state: S3 S4 S5
hw.acpi.s4bios: 0Use acpiconf -s to test
S3,
S4OS, and
S5. An of one
(1), indicates
S4BIOS support instead
of S4 OS.When testing suspend/resume, start with
S1, if supported. This state is most
likely to work since it does not require much driver
support. No one has implemented S2,
which is similar to S1. Next, try
S3. This is the deepest
STR state and requires a lot of driver
support to properly reinitialize the hardware. If there are
problems resuming, email &a.acpi.name;. However, the
problem may not be resolved quickly since due to the amount
of drivers and hardware that need more testing and
work.A common problem with suspend/resume is that many device
drivers do not save, restore, or reinitialize their
firmware, registers, or device memory properly. As a first
attempt at debugging the problem, try:&prompt.root; sysctl debug.bootverbose=1
&prompt.root; sysctl debug.acpi.suspend_bounce=1
&prompt.root; acpiconf -s 3This test emulates the suspend/resume cycle of all
device drivers without actually going into
S3 state. In some cases, problems such
as losing firmware state, device watchdog time out, and
retrying forever, can be captured with this method. Note
that the system will not really enter S3
state, which means devices may not lose power, and many
will work fine even if suspend/resume methods are totally
missing, unlike real S3 state.Harder cases require additional hardware, such as a
serial port and cable for debugging through a serial
console, a Firewire port and cable for using &man.dcons.4;,
and kernel debugging skills.To help isolate the problem, remove as many drivers
from the kernel as possible. If it works, narrow down which
driver is the problem by loading drivers until it fails
again. Typically, binary drivers like
nvidia.ko, display drivers, and
USB will have the most problems while
Ethernet interfaces usually work fine. If drivers can be
properly loaded and unloaded, automate this by putting the
appropriate commands in
/etc/rc.suspend and
/etc/rc.resume.
Try setting to
0 if the display is messed up after
resume. Try setting longer or shorter values for
to see if that
helps.Try loading a recent &linux; distribution to see if
suspend/resume works on the same hardware. If it works on
&linux;, it is likely a &os; driver problem. Narrowing down
which driver causes the problem will assist developers in
fixing the problem. Since the ACPI
maintainers rarely maintain other drivers, such as sound
or ATA, any driver problems should also
be posted to the &a.current.name; list and mailed to the
driver maintainer. Advanced users can include debugging
&man.printf.3;s in a problematic driver to track down where
in its resume function it hangs.Finally, try disabling ACPI and
enabling APM instead. If suspend/resume
works with APM, stick with
APM, especially on older hardware
(pre-2000). It took vendors a while to get
ACPI support correct and older hardware
is more likely to have BIOS problems with
ACPI.System HangsMost system hangs are a result of lost interrupts or an
interrupt storm. Chipsets may have problems based on boot,
how the BIOS configures interrupts before
correctness of the APIC
(MADT) table, and routing of the
System Control Interrupt
(SCI).interrupt stormsInterrupt storms can be distinguished from lost
interrupts by checking the output of
vmstat -i and looking at the line that
has acpi0. If the counter is increasing
at more than a couple per second, there is an interrupt
storm. If the system appears hung, try breaking to
DDB (CTRLALTESC on console) and type
show interrupts.APICdisablingWhen dealing with interrupt problems, try disabling
APIC support with
hint.apic.0.disabled="1" in
/boot/loader.conf.PanicsPanics are relatively rare for ACPI
and are the top priority to be fixed. The first step is to
isolate the steps to reproduce the panic, if possible, and
get a backtrace. Follow the advice for enabling
options DDB and setting up a serial
console in or setting
up a &man.dump.8; partition. To get a backtrace in
DDB, use tr. When
handwriting the backtrace, get at least the last five
and the top five lines in the trace.Then, try to isolate the problem by booting with
ACPI disabled. If that works, isolate
the ACPI subsystem by using various
values of . See
&man.acpi.4; for some examples.System Powers Up After Suspend or ShutdownFirst, try setting
hw.acpi.disable_on_poweroff="0" in
&man.loader.conf.5;. This keeps ACPI
from disabling various events during the shutdown process.
Some systems need this value set to 1
(the default) for the same reason. This usually fixes the
problem of a system powering up spontaneously after a
suspend or poweroff.Other ProblemsFor other problems with ACPI, such as
it not working with a docking station or devices not being
detected, email a description to &a.acpi.name;. Some
issues may be related to unfinished parts of the
ACPI subsystem which might take a while
to be implemented. Be patient and prepared to test
patches.ASL, &man.acpidump.8;, and
IASLACPIASLSome BIOS vendors provide incorrect
or buggy bytecode. This is usually manifested by kernel
console messages like this:ACPI-1287: *** Error: Method execution failed [\\_SB_.PCI0.LPC0.FIGD._STA] \\
(Node 0xc3f6d160), AE_NOT_FOUNDOften, these problems may be resolved by updating the
BIOS to the latest revision. Most console
messages are harmless, but if there are other problems like
the battery status is not working, these messages are a
good place to start looking for problems. The bytecode,
known as AML, is compiled from a source
language called ASL. The
AML is found in the table known as the
DSDT. To get a copy of the system's
ASL, use &man.acpidump.8;. Include both
, to show the contents of the fixed tables,
and , to disassemble the
AML. Refer to
for an example
syntax.The simplest first check is to recompile the
ASL to check for errors. Warnings can
usually be ignored, but errors are bugs that will usually
prevent ACPI from working correctly. To
recompile the ASL, issue the following
command:&prompt.root; iasl your.aslFixing the ASLACPIASLThe goal of &os; is for everyone to have working
ACPI without any user intervention. At
this point, workarounds are still being developed for common
mistakes made by BIOS vendors. The
µsoft; interpreter (acpi.sys and
acpiec.sys) does not strictly check for
adherence to the standard, and thus many
BIOS vendors who only test
ACPI under &windows; never fix their
ASL. &os; developers continue to identify
and document which non-standard behavior is allowed by
µsoft;'s interpreter and replicate it so that &os; can
work without forcing users to fix the ASL.
As a workaround, and to help identify behavior, fix the
ASL manually. If this works, send a
&man.diff.1; of the old and new ASL so
developers can possibly work around the buggy behavior in
ACPI-CA.ACPIerror messagesHere is a list of common error messages, their cause, and
how to fix them:Operating System DependenciesSome AML versions assume the user is
running &windows;. To override this, set
hw.acpi.osname="Windows
2001" in
/boot/loader.conf, using the strings
in the ASL.Missing Return StatementsSome methods do not explicitly return a value as the
standard requires. While ACPI-CA
does not handle this, &os; has a workaround that allows it
to return the value implicitly. Explicit return statements
can be added where required if the value which should be
returned is known. To force &man.iasl.8; to compile the
ASL, use the
flag.Overriding the Default AMLAfter customizing your.asl, compile
it with this command:&prompt.root; iasl your.aslAdding the flag forces creation
of the AML, even if there are errors
during compilation. Some errors, such as missing return
statements, are automatically worked around by the
interpreter.The default output filename for &man.iasl.8; is
DSDT.aml. Load this file instead of
the BIOS's buggy copy, which is still
present in flash memory, by editing
/boot/loader.conf as follows:acpi_dsdt_load="YES"
acpi_dsdt_name="/boot/DSDT.aml"Be sure to copy DSDT.aml to
/boot.Getting Debugging Output from
ACPIACPIproblemsACPIdebuggingThe ACPI driver has a flexible
debugging facility. A set of subsystems and the level of
verbosity can be specified. The subsystems to debug are
specified as layers and are broken down into
ACPI-CA components (ACPI_ALL_COMPONENTS)
and ACPI hardware support
(ACPI_ALL_DRIVERS). The verbosity of debugging output is
specified as the level and ranges from
ACPI_LV_ERROR (just report errors) to ACPI_LV_VERBOSE
(everything). The level is a bitmask so
multiple options can be set at once, separated by spaces. In
practice, a serial console should be used to log the output
so it is not lost as the console message buffer flushes.
A full list of the individual layers and levels is found in
&man.acpi.4;.Debugging output is not enabled by default. To enable it,
add options ACPI_DEBUG to the kernel
configuration file if ACPI is compiled into
the kernel. Add ACPI_DEBUG=1 to
/etc/make.conf to enable it globally.
If it is a module, recompile just the
acpi.ko module as follows:&prompt.root; cd /sys/modules/acpi/acpi
&& make clean &&
make ACPI_DEBUG=1Install acpi.ko in
/boot/kernel and add the desired level
and layer to /boot/loader.conf. This
example enables debug messages for all
ACPI-CA components and all
ACPI hardware drivers such as
(CPU and LID. It only
outputs error messages at the least verbose level.debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
debug.acpi.level="ACPI_LV_ERROR"If the required information is triggered by a specific
event, such as a suspend and then resume, leave out changes to
/boot/loader.conf and instead use
&man.sysctl.8; to specify the layer and level after booting
and preparing the system for the specific event. The
variables which can be set using &man.sysctl.8; are named
the same as the tunables in
/boot/loader.conf.ReferencesMore information about ACPI may be
found in the following locations:The &a.acpi;The ACPI Mailing List Archives http://lists.freebsd.org/pipermail/freebsd-acpi/The old ACPI Mailing List Archives
http://home.jp.FreeBSD.org/mail-list/acpi-jp/The ACPI 2.0 Specification http://acpi.info/spec.htm&man.acpi.4;, &man.acpi.thermal.4;, &man.acpidump.8;,
&man.iasl.8;, and &man.acpidb.8;DSDT
debugging resource.