[Xenomai-core] Debugging Xenomai kernel

[Xenomai-core] Debugging Xenomai kernel

[zenati]

Dear,

I'm trying to debug Xenomai kernel with GDB and Qemu. So, I launch 
Xenomai in Qemu and make it waiting for GDB. Then I start GDB and 
connect them to Qemu, make breakpoint at the desired function to debug 
and start Xenomai. If the function belongs to the linux kernel, the 
execution stop at the breakpoint. But, if the function belongs to the 
Xenomai nucleus, GDB recognize the breakpoint at the execution but don't 
stop.

Is it possible to debug Xenomai with GDB and Qemu?
Is it the good way to debug?

Thank you for your attention and your help.
Sincerely,

Omar ZENATI

Re: [Xenomai-core] Debugging Xenomai kernel

[Jan Kiszka]

On 2011-07-26 13:54, zenati wrote:
> Dear,
> 
> I'm trying to debug Xenomai kernel with GDB and Qemu.

QEMU in emulation or KVM mode?

> So, I launch
> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
> connect them to Qemu, make breakpoint at the desired function to debug
> and start Xenomai. If the function belongs to the linux kernel, the
> execution stop at the breakpoint. But, if the function belongs to the
> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
> stop.

Is Xenomai built as module or part of the main kernel image? The latter
is simpler to handle as you don't have to deal with modules as symbol
sources, find out their addresses, and load them at the right location.

> 
> Is it possible to debug Xenomai with GDB and Qemu?

Definitely.

> Is it the good way to debug?
> 
> Thank you for your attention and your help.
> Sincerely,
> 
> Omar ZENATI

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Xenomai-core] Debugging Xenomai kernel

[zenati]

On 07/27/2011 11:23 AM, Jan Kiszka wrote:
> On 2011-07-26 13:54, zenati wrote:
>> Dear,
>>
>> I'm trying to debug Xenomai kernel with GDB and Qemu.
> QEMU in emulation or KVM mode?
>
I'm using Qemu in emulation mode.
>> So, I launch
>> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
>> connect them to Qemu, make breakpoint at the desired function to debug
>> and start Xenomai. If the function belongs to the linux kernel, the
>> execution stop at the breakpoint. But, if the function belongs to the
>> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
>> stop.
> Is Xenomai built as module or part of the main kernel image? The latter
> is simpler to handle as you don't have to deal with modules as symbol
> sources, find out their addresses, and load them at the right location.
>
Xenomai is built as a part of the main kernel.
>> Is it possible to debug Xenomai with GDB and Qemu?
> Definitely.
>
>> Is it the good way to debug?
>>
>> Thank you for your attention and your help.
>> Sincerely,
>>
>> Omar ZENATI
> Jan
>

Omar ZENATI

Re: [Xenomai-core] Debugging Xenomai kernel

[Jan Kiszka]

On 2011-07-27 14:01, zenati wrote:
> On 07/27/2011 11:23 AM, Jan Kiszka wrote:
>> On 2011-07-26 13:54, zenati wrote:
>>> Dear,
>>>
>>> I'm trying to debug Xenomai kernel with GDB and Qemu.
>> QEMU in emulation or KVM mode?
>>
> I'm using Qemu in emulation mode.

What's your target arch? x84-64, x86-32, or some ARM or PPC etc.?

>>> So, I launch
>>> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
>>> connect them to Qemu, make breakpoint at the desired function to debug
>>> and start Xenomai. If the function belongs to the linux kernel, the
>>> execution stop at the breakpoint. But, if the function belongs to the
>>> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
>>> stop.
>> Is Xenomai built as module or part of the main kernel image? The latter
>> is simpler to handle as you don't have to deal with modules as symbol
>> sources, find out their addresses, and load them at the right location.
>>
> Xenomai is built as a part of the main kernel.

OK. Check during runtime of the guest if the disassembly at the desired
breakpoint address matches the compiled code. Maybe there is some
accidental discrepancy.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Xenomai-core] Debugging Xenomai kernel

[zenati]

On 07/27/2011 02:12 PM, Jan Kiszka wrote:
> On 2011-07-27 14:01, zenati wrote:
>> On 07/27/2011 11:23 AM, Jan Kiszka wrote:
>>> On 2011-07-26 13:54, zenati wrote:
>>>> Dear,
>>>>
>>>> I'm trying to debug Xenomai kernel with GDB and Qemu.
>>> QEMU in emulation or KVM mode?
>>>
>> I'm using Qemu in emulation mode.
> What's your target arch? x84-64, x86-32, or some ARM or PPC etc.
x86-32
>>>> So, I launch
>>>> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
>>>> connect them to Qemu, make breakpoint at the desired function to debug
>>>> and start Xenomai. If the function belongs to the linux kernel, the
>>>> execution stop at the breakpoint. But, if the function belongs to the
>>>> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
>>>> stop.
>>> Is Xenomai built as module or part of the main kernel image? The latter
>>> is simpler to handle as you don't have to deal with modules as symbol
>>> sources, find out their addresses, and load them at the right location.
>>>
>> Xenomai is built as a part of the main kernel.
> OK. Check during runtime of the guest if the disassembly at the desired
> breakpoint address matches the compiled code. Maybe there is some
> accidental discrepancy.
The breakpoints match correctly the compiled code. Anyway, it must stop 
at the breakpoint. No?
> Jan
>

Re: [Xenomai-core] Debugging Xenomai kernel

[Jan Kiszka]

On 2011-07-27 18:13, zenati wrote:
> On 07/27/2011 02:12 PM, Jan Kiszka wrote:
>> On 2011-07-27 14:01, zenati wrote:
>>> On 07/27/2011 11:23 AM, Jan Kiszka wrote:
>>>> On 2011-07-26 13:54, zenati wrote:
>>>>> Dear,
>>>>>
>>>>> I'm trying to debug Xenomai kernel with GDB and Qemu.
>>>> QEMU in emulation or KVM mode?
>>>>
>>> I'm using Qemu in emulation mode.
>> What's your target arch? x84-64, x86-32, or some ARM or PPC etc.
> x86-32
>>>>> So, I launch
>>>>> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
>>>>> connect them to Qemu, make breakpoint at the desired function to debug
>>>>> and start Xenomai. If the function belongs to the linux kernel, the
>>>>> execution stop at the breakpoint. But, if the function belongs to the
>>>>> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
>>>>> stop.
>>>> Is Xenomai built as module or part of the main kernel image? The latter
>>>> is simpler to handle as you don't have to deal with modules as symbol
>>>> sources, find out their addresses, and load them at the right location.
>>>>
>>> Xenomai is built as a part of the main kernel.
>> OK. Check during runtime of the guest if the disassembly at the desired
>> breakpoint address matches the compiled code. Maybe there is some
>> accidental discrepancy.
> The breakpoints match correctly the compiled code. Anyway, it must stop 
> at the breakpoint. No?

...if the guest actually executes that address.

I haven't used x86 QEMU in emulation mode for quite a while to debug
something. Maybe we have a regression there. What's your QEMU version?
Do you have a chance to test with a KVM host? It's faster anyway.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Xenomai-core] Debugging Xenomai kernel

[zenati]

On 07/27/2011 06:16 PM, Jan Kiszka wrote:
> On 2011-07-27 18:13, zenati wrote:
>> On 07/27/2011 02:12 PM, Jan Kiszka wrote:
>>> On 2011-07-27 14:01, zenati wrote:
>>>> On 07/27/2011 11:23 AM, Jan Kiszka wrote:
>>>>> On 2011-07-26 13:54, zenati wrote:
>>>>>> Dear,
>>>>>>
>>>>>> I'm trying to debug Xenomai kernel with GDB and Qemu.
>>>>> QEMU in emulation or KVM mode?
>>>>>
>>>> I'm using Qemu in emulation mode.
>>> What's your target arch? x84-64, x86-32, or some ARM or PPC etc.
>> x86-32
>>>>>> So, I launch
>>>>>> Xenomai in Qemu and make it waiting for GDB. Then I start GDB and
>>>>>> connect them to Qemu, make breakpoint at the desired function to debug
>>>>>> and start Xenomai. If the function belongs to the linux kernel, the
>>>>>> execution stop at the breakpoint. But, if the function belongs to the
>>>>>> Xenomai nucleus, GDB recognize the breakpoint at the execution but don't
>>>>>> stop.
>>>>> Is Xenomai built as module or part of the main kernel image? The latter
>>>>> is simpler to handle as you don't have to deal with modules as symbol
>>>>> sources, find out their addresses, and load them at the right location.
>>>>>
>>>> Xenomai is built as a part of the main kernel.
>>> OK. Check during runtime of the guest if the disassembly at the desired
>>> breakpoint address matches the compiled code. Maybe there is some
>>> accidental discrepancy.
>> The breakpoints match correctly the compiled code. Anyway, it must stop
>> at the breakpoint. No?
> ...if the guest actually executes that address.
>
> I haven't used x86 QEMU in emulation mode for quite a while to debug
> something. Maybe we have a regression there. What's your QEMU version?
QEMU PC emulator version 0.12.3 (qemu-kvm-0.12.3), Copyright (c) 
2003-2008 Fabrice Bellard
> Do you have a chance to test with a KVM host? It's faster anyway.
I never used it before... But I'm ready to test it if there is no others 
ways to debug.
> Jan
>

Omar ZENATi