[uml-user] gdb: SIGTRAP at proc_fs.h:190

[Franz L. <fra...@we...>]

Hello,

I have a problem debugging the uml kernel using gdb in SKAS mode. 
What happens is that right after running the kernel in gdb, it immediately 
hits a breakpoint in proc_fs.h. Once I continue, it keeps hitting that 
breakpoint a few times, then moves on to break in swab.h etc. Also it's not 
possible to clear the breakpoints from within gdb. See attached gdb session 
at the end of my message.

My questions: 
a) How can I clear those breakpoints I didn't set?
and even more important
b) How did they get there, why is a SIGTRAP received at proc_fs.h:190, 
swab.h:135, etc.

I am using the vanilla 2.6.14 kernel source patched with uml-2.6.14-bs1.patch. 
In kernel configuration, tt mode, skas mode, kallsyms, ptrace etc. are 
enabled. Supplying mode=skas0 or compiling the kernel without tt mode doesn't 
change anything.
Furthermore, I'm not able to debug in tt mode, if you wish I can write about 
that in another posting. Therefore, could it have something to do with my 
version of gdb (6.3)?

Kind regards,
Franz Lenhardt

---snip: gdb session---
undercity:/home/lenhardt/Documents/Implementation/sr/uml # gdb linux-sr
GNU gdb 6.3
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i586-suse-linux"...Using host libthread_db library 
"/lib/tls/libthread_db.so.1".

(gdb) b route.c:931
Breakpoint 1 at 0xa01d7b58: file route.c, line 931.
(gdb) r ubd0=root.img ubd1=swap.img
Starting program: /home/lenhardt/Documents/Implementation/sr/uml/linux-sr 
ubd0=root.img ubd1=swap.img

Program received signal SIGTRAP, Trace/breakpoint trap.
0xa001a003 in _start () at proc_fs.h:190
190                     res->proc_fops = fops;
(gdb) c
Continuing.

Program received signal SIGTRAP, Trace/breakpoint trap.
0xa001a005 in _start () at proc_fs.h:190
190                     res->proc_fops = fops;
(gdb) clear
No breakpoint at this line.
---snap: gdb session---