Issue: qemu-kvm with gdb

Issue: qemu-kvm with gdb

[shiv chauhan]

Hi all,

While remote debugging a kernel (not written in C and no debugging
symbols) using qemu-kvm with gdb, strange it does not stop at
breakpoint though qemu works well:

Commands:
 # qemu-kvm -s -S -hda hd.img &
#gdb
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
0x0000fff0 in ?? ()
(gdb) break *0x200020
Breakpoint 1 at 0x200020
(gdb) c

This break point never reach, though I am sure this address comes in
execution control path, above all same sequence of commands work well
with qemu, anybody else faced such issue? or any explanation for this
behavior?


Thanks,
SPC

Re: Issue: qemu-kvm with gdb

[Jan Kiszka]

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On 2011-03-24 07:17, shiv chauhan wrote:
> Hi all,
> 
> While remote debugging a kernel (not written in C and no debugging
> symbols) using qemu-kvm with gdb, strange it does not stop at
> breakpoint though qemu works well:
> 
> Commands:
>  # qemu-kvm -s -S -hda hd.img &
> #gdb
> (gdb) target remote localhost:1234
> Remote debugging using localhost:1234
> 0x0000fff0 in ?? ()
> (gdb) break *0x200020
> Breakpoint 1 at 0x200020
> (gdb) c
> 
> This break point never reach, though I am sure this address comes in
> execution control path, above all same sequence of commands work well
> with qemu, anybody else faced such issue? or any explanation for this
> behavior?

Breakpoints in emulation mode are like hardware breakpoints: It doesn't
matter if the guest writes to their location. However, KVM software
breakpoints (the default) work via injecting an INT3 into the guest
code. So you may be more lucky with hbreak.

Jan



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