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FreeBSD host notes:
- needs to run as root in order to use /dev/tap* networking (why?)
(actually RELENG_6 and above now has a sysctl net.link.tap.user_open
to allow users to use it too.  don't forget to adjust device node
permissions in /etc/devfs.rules.)
- slirp (usermode networking) is fixed now in cvs, on FreeSBIE 1.0 guests
you still have to manually do:
	echo nameserver 10.0.2.3 >/etc/resolv.conf
but i've been told that that's normal. (fixed on FreeSBIE 1.1.)
and you have to wait a bit for dhclient to do its thing; traffic to
address 10.0.2.2 is routed to 127.1 on the host.
- expect timer problems when guest kernel HZ is > hosts,
for example time sleep 1 takes 49 seconds and booting sleeps for
minutes at the acd0 probe with a FreeSBIE 1.0 guest, thats because
its kernel is built with HZ=5000, and FreeBSD's default is 100...
(no longer a problem with FreeSBIE 1.1.)  The linux 2.6 kernel uses
1000 by default btw (changed to 250 recently).  Enabling /dev/rtc doesn't
seem to help either (not included since it needs a patch to emulators/rtc.)
- using physical media doesn't work on 4.x hosts (missing DIOCGMEDIASIZE
ioctl.)
- the -smb option (smb-export local dir to guest) needs the net/samba3
port/package installed in addition to qemu.
- RELENG_6 and up guests often crash while accessing the emulated cdrom
(see kern/84102, http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/84102),
using a kernel without PREEMPTION has been reported to fix this problem.
(or do an ftp install instead of installing from the emulated cdrom, and
then make a new kernel.)  [fixed since 6.0-R.]
- 6.0-RC1 was released with an ed driver that doesn't like qemu's emulated
RTL8029 nic, this has been fixed in the meantime but if for some reason
you need to use that version as a guest you can temporarily add the patch
in this message: http://docs.freebsd.org/cgi/mid.cgi?200510131428.21211.jkim
(not included in the port since the used VIA VT86C926 PCI ID does not
really match the emulated nic exactly, it just `happens' to work with
6.0-RC1's driver.)
- if you want to use usb devices connected to the host in the guest
(usb_add host:... monitor command) you need to make sure the host isn't
claiming them, e.g. for umass devices (like memory sticks or external
harddrives) make sure umass isn't in the kernel (you can then still load it
as a kld when needed), also unless you are running qemu as root you then
need to fix permissions for /dev/ugen* device nodes: if you are on 5.x or
later (devfs) put a rule in /etc/devfs.rules, activate it in /etc/rc.conf
and run /etc/rc.d/devfs restart.  example devfs.rules:
	[ugen_ruleset=20]
	add path 'ugen*' mode 660 group operator
corresponding rc.conf line:
	devfs_system_ruleset="ugen_ruleset"
- still usb: since the hub is no longer attached to the uchi controller
and the wakeup mechanism, resume interrupt is not implemented yet linux
guests will suspend the bus, i.e. they wont see devices usb_add'ed after
its (linux') uhci module got loaded.  workaround: either add devices
before linux loads the module or rmmod and modprobe it afterwards.
- to avoid panics or non-working re(4) nics with FreeBSD guests if you
use qemu -net nic,model=rtl8139 -net user or tap ... enable the emulated
rtl8139 timer by building the port with RTL8139_TIMER enabled.
(the rtl8139c+ that model=rtl8139 emulates needs less cpu than qemu's
default ne2k nic which is driven by ed(4), it has not been made default
only because it may not work with all guests yet.  btw qemu now also can
emulate a few intel eepro100 nics which seem to be a tad more efficient
even, and at least i82557b works without tweaks for FreeBSD guests - driven
by fxp(4) - and Linux guests too.)
- if you get repeated `atapi_poll called!' console messages with FreeBSD
guests or other weird cdrom problems then thats probably because the guest
has atapicam loaded, which for reasons still to be determined has problems
with qemu's now by default enabled cdrom dma.  You can build the port with
CDROM_DMA disabled to disable it.
- if you build qemu wihout SDL and then get crashes running it try
passing it -nographic.  This should probably be default in that case...
- slirp (-net user) seems to be unstable on amd64 hosts, if this affects
you please use tuntap for now.  Scott Robbins posted a tap howto for
-current here:
	http://forums.bsdnexus.com/viewtopic.php?id=1563
and one for 6 and 5(?) is here:
	http://acidos.bandwidth-junkies.net/index.php?Sect=qemu
- perhaps it should be noted that if you want to use qemu with -m 512
or larger on i386 hosts you need to increase the kern.maxdsiz tunable
in loader.conf(5) since the default is 512 MB, and qemu needs memory for
itself also.
- if you use kqemu make sure your kqemu.ko is always in sync with your
kernel (like with any kld installed outside of base), i.e.  rebuild its
port whenever you update the kernel - especially if you are switching
branches or are following a -stable or even -current branch!
- you can enable autoloading of kqemu (and aio) at boot by adding a line
	kqemu_enable=YES
to /etc/rc.conf
- kqemu liked to panic the host on amd64 SMP until before 1.3.0.p11_6
(revision 1.25 of /usr/ports/emulators/kqemu-kmod/Makefile), so if your
host is such you might want to make sure your kqemu-kmod port is new enough.
(and don't forget to reload it...)
- also remember that on amd64 you need to run the amd64 (x86_64) system
emulation if you want to use kqemu, i.e. run qemu-system-x86_64 instead of
qemu (the latter only emulates a 32 bit system.)  Unfortunately there can
still be guests that don't run correctly in the amd64 emulation even when
they do run in the 32 bit one, the same is true about kqemu and -kernel-kqemu
on amd64 - not much you can do about that other than help debugging (k)qemu's
amd64 emulation... (well or falling back to unaccellerated, possibly 32 bit
qemu/leaving out -kernel-kqemu if its that what's causing the problems.)
- qemu's network boot roms (-boot n) have a bug when bootfiles sizes are a
multiple of blksize, if this affects you (like with FreeBSD's /boot/pxeboot)
you can do like
	cp /boot/pxeboot pxeboot-qemu && chmod +w pxeboot-qemu && echo >>pxeboot-qemu
and then use pxeboot-qemu.  Actually you need latest -stable or -current
btx code (from after 7.0 was released) because of the real mode boot problem,
so use at least pxeboot from there.  And I just did that for the pxeboot
extracted out of
	ftp://ftp.freebsd.org/pub/FreeBSD/snapshots/200805/7.0-STABLE-200805-i386-bootonly.iso
and placed it here:
	http://people.freebsd.org/~nox/qemu/pxeboot-qemu
- qemu now uses aio at least for ide dma, so if you get `Invalid system call'
crashes that is because aio is not (kld)loaded.
- The default configuration location (qemu-ifup script etc.) has been
changed from /etc to PREFIX/etc (usually /usr/local/etc).  Move your
files accordingly.
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