Implement NetGDB(4)

NetGDB(4) is a component of a system using a panic-time network stack to
remotely debug crashed FreeBSD kernels over the network, instead of
traditional serial interfaces.

There are three pieces in the complete NetGDB system.

First, a dedicated proxy server must be running to accept connections from
both NetGDB and gdb(1), and pass bidirectional traffic between the two
protocols.

Second, the NetGDB client is activated much like ordinary 'gdb' and
similarly to 'netdump' in ddb(4) after a panic.  Like other debugnet(4)
clients (netdump(4)), the network interface on the route to the proxy server
must be online and support debugnet(4).

Finally, the remote (k)gdb(1) uses 'target remote <proxy>:<port>' (like any
other TCP remote) to connect to the proxy server.

The NetGDB v1 protocol speaks the literal GDB remote serial protocol, and
uses a 1:1 relationship between GDB packets and sequences of debugnet
packets (fragmented by MTU).  There is no encryption utilized to keep
debugging sessions private, so this is only appropriate for local
segments or trusted networks.

Submitted by:	John Reimer <john.reimer AT emc.com> (earlier version)
Discussed some with:	emaste, markj
Relnotes:	sure
Differential Revision:	https://reviews.freebsd.org/D21568

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/i386/conf/GENERIC b/sys/i386/conf/GENERIC
index 4d29e889defd..0aef50a08ea0 100644
--- a/sys/i386/conf/GENERIC
+++ b/sys/i386/conf/GENERIC
@@ -101,6 +101,7 @@ options 	GZIO			# gzip-compressed kernel and user dumps
 options 	ZSTDIO			# zstd-compressed kernel and user dumps
 options 	DEBUGNET		# debugnet networking
 options 	NETDUMP			# netdump(4) client support
+options 	NETGDB			# netgdb(4) client support
 
 # To make an SMP kernel, the next two lines are needed
 options 	SMP			# Symmetric MultiProcessor Kernel