[Qemu-devel] How to debug Linux kernel on qemu with kgdb?

[Qemu-devel] How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

hi,

I am trying to use debug kgdb patched linux kernel on my qemu. Both
the native and target platform are IA32. I am wondering if there is
anyone can show me the procedure?

Thanks,
Neo
-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Jan Kiszka]

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Neo Jia wrote:
> hi,
> 
> I am trying to use debug kgdb patched linux kernel on my qemu. Both
> the native and target platform are IA32. I am wondering if there is
> anyone can show me the procedure?

Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html

(BTW, I think that kgdb bug is still unfixed - I never got a feedback.)

Jan


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[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> Neo Jia wrote:
> > hi,
> >
> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
> > the native and target platform are IA32. I am wondering if there is
> > anyone can show me the procedure?
>
> Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
>
> (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)

I can connect gdb through /dev/pts/XX. My qemu is lanuched by

qemu -nographic -hda linux.img -kernel
./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
ide4=noprobe ide5=noprobe"

Do you know where can I get the console output?

I would like to work out kgdb + qemu to debug linux kernel.

Thanks,
Neo

>
> Jan
>
>
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Neo Jia <neojia@gmail.com> wrote:
> On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> > Neo Jia wrote:
> > > hi,
> > >
> > > I am trying to use debug kgdb patched linux kernel on my qemu. Both
> > > the native and target platform are IA32. I am wondering if there is
> > > anyone can show me the procedure?
> >
> > Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> >
> > (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)
>
> I can connect gdb through /dev/pts/XX. My qemu is lanuched by
>
> qemu -nographic -hda linux.img -kernel
> ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> ide4=noprobe ide5=noprobe"
>
> Do you know where can I get the console output?
>
> I would like to work out kgdb + qemu to debug linux kernel.
>
> Thanks,
> Neo
>

BTW, the error message I got is "Program terminated with signal 0, Signal 0."

Thanks,
Neo

> >
> > Jan
> >
> >
> >
>
>
> --
> I would remember that if researchers were not ambitious
> probably today we haven't the technology we are using!
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Jan Kiszka]

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Neo Jia wrote:
> On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> Neo Jia wrote:
>> > hi,
>> >
>> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
>> > the native and target platform are IA32. I am wondering if there is
>> > anyone can show me the procedure?
>>
>> Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
>>
>> (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)
> 
> I can connect gdb through /dev/pts/XX. My qemu is lanuched by
> 
> qemu -nographic -hda linux.img -kernel
> ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> ide4=noprobe ide5=noprobe"
> 
> Do you know where can I get the console output?
> 

Use "... -serial stdio -serial pty ..." and attached kgdb to the second
serial port (I think to recall that is default anyway). The first one is
then used for the kernel console.

> I would like to work out kgdb + qemu to debug linux kernel.

??? So you really want to debug the kernel when kgdb is applied, ie.
actually debug kgdb? If you only intend to debug the kernel itself, qemu
-s + gdb is enough.

Jan


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[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> Neo Jia wrote:
> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> Neo Jia wrote:
> >> > hi,
> >> >
> >> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
> >> > the native and target platform are IA32. I am wondering if there is
> >> > anyone can show me the procedure?
> >>
> >> Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> >>
> >> (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)
> >
> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
> >
> > qemu -nographic -hda linux.img -kernel
> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> > ide4=noprobe ide5=noprobe"
> >
> > Do you know where can I get the console output?
> >
>
> Use "... -serial stdio -serial pty ..." and attached kgdb to the second
> serial port (I think to recall that is default anyway). The first one is
> then used for the kernel console.
>
> > I would like to work out kgdb + qemu to debug linux kernel.
>
> ??? So you really want to debug the kernel when kgdb is applied, ie.
> actually debug kgdb? If you only intend to debug the kernel itself, qemu
> -s + gdb is enough.

Jan,

I just would like to debug kernel itself. I have tried qemu -s + gdb
but it keeps
getting "apic_timer_interrupt" when I am using "n" command.

The following is the output:

> gdb vmlinux
GNU gdb 6.5.50.20060621-cvs
Copyright (C) 2006 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 "i686-pc-linux-gnu"...Using host
libthread_db library "/lib/tls/libthread_db.so.1".

(gdb) target remote localhost:1234
Remote debugging using localhost:1234
0x0000fff0 in ?? ()
warning: shared library handler failed to enable breakpoint
(gdb) c
Continuing.

Program received signal SIGINT, Interrupt.
default_idle () at include/asm/bitops.h:252
252             return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
(gdb) b sys_ex
sys_execve      sys_exit        sys_exit_group
(gdb) b sys_execve
Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791.
(gdb) c
Continuing.

Breakpoint 1, sys_execve (regs=
      {ebx = 135197704, ecx = 135197864, edx = 135244936, esi =
135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123,
xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582,
esp = -1079177012, xss = 123})
    at arch/i386/kernel/process.c:791
791             filename = getname((char __user *) regs.ebx);
(gdb) n
0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9
9       {
(gdb) quit

Thanks,
Neo

>
> Jan
>
>
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Jan Kiszka]

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Neo Jia wrote:
> On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> Neo Jia wrote:
>> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> >> Neo Jia wrote:
>> >> > hi,
>> >> >
>> >> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
>> >> > the native and target platform are IA32. I am wondering if there is
>> >> > anyone can show me the procedure?
>> >>
>> >> Yep, see
>> https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
>> >>
>> >> (BTW, I think that kgdb bug is still unfixed - I never got a
>> feedback.)
>> >
>> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
>> >
>> > qemu -nographic -hda linux.img -kernel
>> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
>> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
>> > ide4=noprobe ide5=noprobe"
>> >
>> > Do you know where can I get the console output?
>> >
>>
>> Use "... -serial stdio -serial pty ..." and attached kgdb to the second
>> serial port (I think to recall that is default anyway). The first one is
>> then used for the kernel console.
>>
>> > I would like to work out kgdb + qemu to debug linux kernel.
>>
>> ??? So you really want to debug the kernel when kgdb is applied, ie.
>> actually debug kgdb? If you only intend to debug the kernel itself, qemu
>> -s + gdb is enough.
> 
> Jan,
> 
> I just would like to debug kernel itself. I have tried qemu -s + gdb
> but it keeps
> getting "apic_timer_interrupt" when I am using "n" command.
> 
> The following is the output:
> 
>> gdb vmlinux
> GNU gdb 6.5.50.20060621-cvs
> Copyright (C) 2006 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 "i686-pc-linux-gnu"...Using host
> libthread_db library "/lib/tls/libthread_db.so.1".
> 
> (gdb) target remote localhost:1234
> Remote debugging using localhost:1234
> 0x0000fff0 in ?? ()
> warning: shared library handler failed to enable breakpoint
> (gdb) c
> Continuing.
> 
> Program received signal SIGINT, Interrupt.
> default_idle () at include/asm/bitops.h:252
> 252             return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
> (gdb) b sys_ex
> sys_execve      sys_exit        sys_exit_group
> (gdb) b sys_execve
> Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791.
> (gdb) c
> Continuing.
> 
> Breakpoint 1, sys_execve (regs=
>      {ebx = 135197704, ecx = 135197864, edx = 135244936, esi =
> 135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123,
> xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582,
> esp = -1079177012, xss = 123})
>    at arch/i386/kernel/process.c:791
> 791             filename = getname((char __user *) regs.ebx);
> (gdb) n
> 0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9
> 9       {

That's normal. You stopped the kernel in sys_execve with interrupts
enabled. When continuing, qemu replays any pending interrupts, here the
timer. Thus your next instruction is not in sys_execve, but in the
interrupt handler. You can try finish then and hope that you will return
to the next line in sys_execve, or you put another breakpoint at the
next interesting spot and just issue continue.

Jan


PS: Using kgdb from inside qemu should work (at least it once did for
me), but it is really sloooow.


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[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> Neo Jia wrote:
> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> Neo Jia wrote:
> >> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> >> Neo Jia wrote:
> >> >> > hi,
> >> >> >
> >> >> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
> >> >> > the native and target platform are IA32. I am wondering if there is
> >> >> > anyone can show me the procedure?
> >> >>
> >> >> Yep, see
> >> https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> >> >>
> >> >> (BTW, I think that kgdb bug is still unfixed - I never got a
> >> feedback.)
> >> >
> >> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
> >> >
> >> > qemu -nographic -hda linux.img -kernel
> >> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> >> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> >> > ide4=noprobe ide5=noprobe"
> >> >
> >> > Do you know where can I get the console output?
> >> >
> >>
> >> Use "... -serial stdio -serial pty ..." and attached kgdb to the second
> >> serial port (I think to recall that is default anyway). The first one is
> >> then used for the kernel console.
> >>
> >> > I would like to work out kgdb + qemu to debug linux kernel.
> >>
> >> ??? So you really want to debug the kernel when kgdb is applied, ie.
> >> actually debug kgdb? If you only intend to debug the kernel itself, qemu
> >> -s + gdb is enough.
> >
> > Jan,
> >
> > I just would like to debug kernel itself. I have tried qemu -s + gdb
> > but it keeps
> > getting "apic_timer_interrupt" when I am using "n" command.
> >
> > The following is the output:
> >
> >> gdb vmlinux
> > GNU gdb 6.5.50.20060621-cvs
> > Copyright (C) 2006 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 "i686-pc-linux-gnu"...Using host
> > libthread_db library "/lib/tls/libthread_db.so.1".
> >
> > (gdb) target remote localhost:1234
> > Remote debugging using localhost:1234
> > 0x0000fff0 in ?? ()
> > warning: shared library handler failed to enable breakpoint
> > (gdb) c
> > Continuing.
> >
> > Program received signal SIGINT, Interrupt.
> > default_idle () at include/asm/bitops.h:252
> > 252             return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
> > (gdb) b sys_ex
> > sys_execve      sys_exit        sys_exit_group
> > (gdb) b sys_execve
> > Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791.
> > (gdb) c
> > Continuing.
> >
> > Breakpoint 1, sys_execve (regs=
> >      {ebx = 135197704, ecx = 135197864, edx = 135244936, esi =
> > 135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123,
> > xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582,
> > esp = -1079177012, xss = 123})
> >    at arch/i386/kernel/process.c:791
> > 791             filename = getname((char __user *) regs.ebx);
> > (gdb) n
> > 0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9
> > 9       {
>
> That's normal. You stopped the kernel in sys_execve with interrupts
> enabled. When continuing, qemu replays any pending interrupts, here the
> timer. Thus your next instruction is not in sys_execve, but in the
> interrupt handler. You can try finish then and hope that you will return
> to the next line in sys_execve, or you put another breakpoint at the
> next interesting spot and just issue continue.
>
> Jan
>
>
> PS: Using kgdb from inside qemu should work (at least it once did for
> me), but it is really sloooow.
>

Could you show me the procedure you did? I just want to use this to
learn kernel code.

Thanks,
Neo

>
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Jan Kiszka]

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Neo Jia wrote:
> On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> Neo Jia wrote:
>> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> >> Neo Jia wrote:
>> >> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
>> >> >> Neo Jia wrote:
>> >> >> > hi,
>> >> >> >
>> >> >> > I am trying to use debug kgdb patched linux kernel on my qemu.
>> Both
>> >> >> > the native and target platform are IA32. I am wondering if
>> there is
>> >> >> > anyone can show me the procedure?
>> >> >>
>> >> >> Yep, see
>> >> https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
>> >> >>
>> >> >> (BTW, I think that kgdb bug is still unfixed - I never got a
>> >> feedback.)
>> >> >
>> >> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
>> >> >
>> >> > qemu -nographic -hda linux.img -kernel
>> >> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
>> >> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
>> >> > ide4=noprobe ide5=noprobe"
>> >> >
>> >> > Do you know where can I get the console output?
>> >> >
>> >>
>> >> Use "... -serial stdio -serial pty ..." and attached kgdb to the
>> second
>> >> serial port (I think to recall that is default anyway). The first
>> one is
>> >> then used for the kernel console.
>> >>
>> >> > I would like to work out kgdb + qemu to debug linux kernel.
>> >>
>> >> ??? So you really want to debug the kernel when kgdb is applied, ie.
>> >> actually debug kgdb? If you only intend to debug the kernel itself,
>> qemu
>> >> -s + gdb is enough.
>> >
>> > Jan,
>> >
>> > I just would like to debug kernel itself. I have tried qemu -s + gdb
>> > but it keeps
>> > getting "apic_timer_interrupt" when I am using "n" command.
>> >
>> > The following is the output:
>> >
>> >> gdb vmlinux
>> > GNU gdb 6.5.50.20060621-cvs
>> > Copyright (C) 2006 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 "i686-pc-linux-gnu"...Using host
>> > libthread_db library "/lib/tls/libthread_db.so.1".
>> >
>> > (gdb) target remote localhost:1234
>> > Remote debugging using localhost:1234
>> > 0x0000fff0 in ?? ()
>> > warning: shared library handler failed to enable breakpoint
>> > (gdb) c
>> > Continuing.
>> >
>> > Program received signal SIGINT, Interrupt.
>> > default_idle () at include/asm/bitops.h:252
>> > 252             return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
>> > (gdb) b sys_ex
>> > sys_execve      sys_exit        sys_exit_group
>> > (gdb) b sys_execve
>> > Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791.
>> > (gdb) c
>> > Continuing.
>> >
>> > Breakpoint 1, sys_execve (regs=
>> >      {ebx = 135197704, ecx = 135197864, edx = 135244936, esi =
>> > 135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123,
>> > xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582,
>> > esp = -1079177012, xss = 123})
>> >    at arch/i386/kernel/process.c:791
>> > 791             filename = getname((char __user *) regs.ebx);
>> > (gdb) n
>> > 0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9
>> > 9       {
>>
>> That's normal. You stopped the kernel in sys_execve with interrupts
>> enabled. When continuing, qemu replays any pending interrupts, here the
>> timer. Thus your next instruction is not in sys_execve, but in the
>> interrupt handler. You can try finish then and hope that you will return
>> to the next line in sys_execve, or you put another breakpoint at the
>> next interesting spot and just issue continue.
>>
>> Jan
>>
>>
>> PS: Using kgdb from inside qemu should work (at least it once did for
>> me), but it is really sloooow.
>>
> 
> Could you show me the procedure you did? I just want to use this to
> learn kernel code.

Did you redirect kgdb to ttyS1?

Jan


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[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> Neo Jia wrote:
> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> Neo Jia wrote:
> >> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> >> Neo Jia wrote:
> >> >> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> >> >> Neo Jia wrote:
> >> >> >> > hi,
> >> >> >> >
> >> >> >> > I am trying to use debug kgdb patched linux kernel on my qemu.
> >> Both
> >> >> >> > the native and target platform are IA32. I am wondering if
> >> there is
> >> >> >> > anyone can show me the procedure?
> >> >> >>
> >> >> >> Yep, see
> >> >> https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> >> >> >>
> >> >> >> (BTW, I think that kgdb bug is still unfixed - I never got a
> >> >> feedback.)
> >> >> >
> >> >> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
> >> >> >
> >> >> > qemu -nographic -hda linux.img -kernel
> >> >> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> >> >> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> >> >> > ide4=noprobe ide5=noprobe"
> >> >> >
> >> >> > Do you know where can I get the console output?
> >> >> >
> >> >>
> >> >> Use "... -serial stdio -serial pty ..." and attached kgdb to the
> >> second
> >> >> serial port (I think to recall that is default anyway). The first
> >> one is
> >> >> then used for the kernel console.
> >> >>
> >> >> > I would like to work out kgdb + qemu to debug linux kernel.
> >> >>
> >> >> ??? So you really want to debug the kernel when kgdb is applied, ie.
> >> >> actually debug kgdb? If you only intend to debug the kernel itself,
> >> qemu
> >> >> -s + gdb is enough.
> >> >
> >> > Jan,
> >> >
> >> > I just would like to debug kernel itself. I have tried qemu -s + gdb
> >> > but it keeps
> >> > getting "apic_timer_interrupt" when I am using "n" command.
> >> >
> >> > The following is the output:
> >> >
> >> >> gdb vmlinux
> >> > GNU gdb 6.5.50.20060621-cvs
> >> > Copyright (C) 2006 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 "i686-pc-linux-gnu"...Using host
> >> > libthread_db library "/lib/tls/libthread_db.so.1".
> >> >
> >> > (gdb) target remote localhost:1234
> >> > Remote debugging using localhost:1234
> >> > 0x0000fff0 in ?? ()
> >> > warning: shared library handler failed to enable breakpoint
> >> > (gdb) c
> >> > Continuing.
> >> >
> >> > Program received signal SIGINT, Interrupt.
> >> > default_idle () at include/asm/bitops.h:252
> >> > 252             return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
> >> > (gdb) b sys_ex
> >> > sys_execve      sys_exit        sys_exit_group
> >> > (gdb) b sys_execve
> >> > Breakpoint 1 at 0xc0101ac1: file arch/i386/kernel/process.c, line 791.
> >> > (gdb) c
> >> > Continuing.
> >> >
> >> > Breakpoint 1, sys_execve (regs=
> >> >      {ebx = 135197704, ecx = 135197864, edx = 135244936, esi =
> >> > 135197704, edi = 135197704, ebp = -1079176984, eax = 11, xds = 123,
> >> > xes = 123, orig_eax = 11, eip = -1208835017, xcs = 115, eflags = 582,
> >> > esp = -1079177012, xss = 123})
> >> >    at arch/i386/kernel/process.c:791
> >> > 791             filename = getname((char __user *) regs.ebx);
> >> > (gdb) n
> >> > 0xc0103666 in apic_timer_interrupt () at include/asm/current.h:9
> >> > 9       {
> >>
> >> That's normal. You stopped the kernel in sys_execve with interrupts
> >> enabled. When continuing, qemu replays any pending interrupts, here the
> >> timer. Thus your next instruction is not in sys_execve, but in the
> >> interrupt handler. You can try finish then and hope that you will return
> >> to the next line in sys_execve, or you put another breakpoint at the
> >> next interesting spot and just issue continue.
> >>
> >> Jan
> >>
> >>
> >> PS: Using kgdb from inside qemu should work (at least it once did for
> >> me), but it is really sloooow.
> >>
> >
> > Could you show me the procedure you did? I just want to use this to
> > learn kernel code.
>
> Did you redirect kgdb to ttyS1?

Yes, I just redirect kgdb to ttyS1 but still nothing. But if I
compiled with "CONFIG_KGDB_CONSOLE=y", it will show on the gdb
console.

Is a bug or wrong configuration?

Thanks,
Neo

>
> Jan
>
>
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Neo Jia]

On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> Neo Jia wrote:
> > On 4/25/07, Jan Kiszka <jan.kiszka@web.de> wrote:
> >> Neo Jia wrote:
> >> > hi,
> >> >
> >> > I am trying to use debug kgdb patched linux kernel on my qemu. Both
> >> > the native and target platform are IA32. I am wondering if there is
> >> > anyone can show me the procedure?
> >>
> >> Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> >>
> >> (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)
> >
> > I can connect gdb through /dev/pts/XX. My qemu is lanuched by
> >
> > qemu -nographic -hda linux.img -kernel
> > ./2.6.15.5-kgdb/vmlinuz-2.6.15.5-kgdb -serial pty -append "kgdbwait
> > console=ttyS0 root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe
> > ide4=noprobe ide5=noprobe"
> >
> > Do you know where can I get the console output?
> >
>
> Use "... -serial stdio -serial pty ..." and attached kgdb to the second
> serial port (I think to recall that is default anyway). The first one is
> then used for the kernel console.

I also tried this but it seems that kgdb cannot connect to /dev/pts/XX
with "-serial stdio".
I did anything wrong?

Thanks,
Neo

>
> > I would like to work out kgdb + qemu to debug linux kernel.
>
> ??? So you really want to debug the kernel when kgdb is applied, ie.
> actually debug kgdb? If you only intend to debug the kernel itself, qemu
> -s + gdb is enough.
>
> Jan
>
>
>


-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

[Qemu-devel] Re: How to debug Linux kernel on qemu with kgdb?

[Jan Kiszka]

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Jan Kiszka wrote:
> Neo Jia wrote:
>> hi,
>>
>> I am trying to use debug kgdb patched linux kernel on my qemu. Both
>> the native and target platform are IA32. I am wondering if there is
>> anyone can show me the procedure?
> 
> Yep, see https://mail.gna.org/public/xenomai-core/2006-09/msg00202.html
> 
> (BTW, I think that kgdb bug is still unfixed - I never got a feedback.)

At the risk of becoming off-topic, but here is the actually related post
on kgdb-bugreport:

http://sourceforge.net/mailarchive/message.php?msg_id=45201805.3090603%40web.de

Jan


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