kgdb ported to devel/gdb

[Andriy Gapon]

On 01/09/2015 00:32, John Baldwin wrote:
> Over the past several months I have ported kgdb to the version of gdb in ports.
> I have a pending patch to the gdb port to add fork following, but once that is
> done (and possibly after updating to 7.10) I will try to add my existing work
> as a KGDB option on the port.  Until such time, you can try the newer kgdb by
> checking out my branch from git.
> 
> Here's my cheat sheet on how to build the newer kgdb.  Note that if you build
> a world with my cross-libkvm patches you should get a kgdb that can debug
> i386 cores on amd64 and vice versa.
> 
> All of the targets that the native devel/gdb support have their backends
> ported (so x86, sparc64, powerpc and powerpc64).  I have not yet ported
> arm or mips since those don't work for userland yet in upstream gdb.  I
> have only compiled non-x86 backends.  Testing of the new kgdb on sparc64
> and powerpc would be appreciated.
> 
> Steps:
> 
> % git clone https://github.com/bsdjhb/gdb.git
> % git checkout freebsd-7.9.1-kgdb
> % fetch http://www.freebsd.org/~jhb/gdb/build
> % pkg install devel/gdb
> 
> # Having gdb installed will mean you get the python bindings in the right
> # place.
> 
> % pkg install gmake
> 
> # I think this is the only build tool you need?
> 
> % ./build
> % cd obj
> 
> # Replace 'obj' with 'obj.<arch>' for all but amd64
> 
> % gmake
> 
> # ... wait
> 
> You will now have a binary at 'obj/gdb/kgdb'.  I just run it from my obj
> tree currently when testing.  Once it becomes part of the port it will get
> installed as /usr/local/bin/kgdb791 or some such.

John,

first of all, thank you very much for this!

I followed your instructions substituting freebsd-7.10-kgdb for
freebsd-7.9.1-kgdb branch (devel/gdb is also at version 7.10) and the build
process worked just fine.
However, when I try to use the new kgdb it works, but I get some annoying
diagnostics:

(kgdb) bt
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
Python Exception <type 'exceptions.ImportError'> No module named gdb.frames:
#0  doadump (textdump=1) at /usr/src/sys/kern/kern_shutdown.c:291
#1  0xffffffff8063453f in kern_reboot (howto=260) at
/usr/src/sys/kern/kern_shutdown.c:359
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#2  0xffffffff80634ba4 in vpanic (fmt=<optimized out>, ap=<optimized out>) at
/usr/src/sys/kern/kern_shutdown.c:635
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#3  0xffffffff806348a3 in panic (fmt=<unavailable>) at
/usr/src/sys/kern/kern_shutdown.c:568
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#4  0xffffffff8041bba7 in db_panic (addr=<optimized out>,
have_addr=<unavailable>, count=<unavailable>, modif=<unavailable>) at
/usr/src/sys/ddb/db_command.c:473
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#5  0xffffffff8041b67b in db_command (last_cmdp=<optimized out>, cmd_table=0x0,
dopager=<optimized out>) at /usr/src/sys/ddb/db_command.c:440
#6  0xffffffff8041b524 in db_command_loop () at /usr/src/sys/ddb/db_command.c:493
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#7  0xffffffff8041de0b in db_trap (type=<optimized out>, code=<unavailable>) at
/usr/src/sys/ddb/db_main.c:251
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#8  0xffffffff80669de8 in kdb_trap (type=19, code=0, tf=0xffffffff80f976d0
<nmi0_stack+3888>) at /usr/src/sys/kern/subr_kdb.c:653
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#9  0xffffffff80820d26 in trap (frame=0xffffffff80f976d0 <nmi0_stack+3888>) at
/usr/src/sys/amd64/amd64/trap.c:381
#10 0xffffffff80809623 in nmi_calltrap () at
/usr/src/sys/amd64/amd64/exception.S:514
Python Exception <type 'exceptions.NameError'> Installation error:
gdb.execute_unwinders function is missing:
#11 0xffffffff80619e1f in __mtx_assert (c=<optimized out>, what=<optimized out>,
file=<optimized out>, line=<optimized out>) at /usr/src/sys/kern/kern_mutex.c:842
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

Did I miss something?
Thanks!

-- 
Andriy Gapon