Re: [Qemu-devel] emulation details of qemu

["Alex Bennée" <alex.bennee@linaro.org>]

tutu sky <ooohooo_u@hotmail.com> writes:

> Yeah, thank you Alex.
> If I use a linux on top of the qemu, for entering debug mode, do i
> need to compile kernel from source or it is not dependent on debugging
> qemu itself?

I'm not sure I follow. As far as QEMU is concerned it provides a stub
for GDB to talk to and doesn't need to know anything else about the
guest it is running. The GDB itself will want symbols one way or another
so you would either compile your kernel from source or pass the debug
symbol enabled vmlinux to GDB using symbol-file.

> and then is it possible to define a heterogeneous multicore platform
> in qemu?

The current upstream QEMU doesn't support heterogeneous setups although
some preliminary work has been posted to allow multiple front-ends to be
compiled together.

There are certainly out-of-tree solutions although as I understand it
(I've not worked with them myself) they use multiple QEMU runtimes
linked together with some sort of shared memory bus/IPC layer.

>
> Thanks and regards.
>
> ________________________________________
> From: Alex Bennée <alex.bennee@linaro.org>
> Sent: Thursday, April 28, 2016 6:45 PM
> To: tutu sky
> Cc: Stefan Hajnoczi; qemu-devel@nongnu.org
> Subject: Re: [Qemu-devel] emulation details of qemu
>
> tutu sky <ooohooo_u@hotmail.com> writes:
>
>> Thanks a lot Stefan,
>> But if i want to change the content of a register during run time in
>> debug mode, what should i do? is it possible at first?
>
> Using the gdbstub sure you can change the register values when the
> machine is halted.
>
>>
>> Regards.
>> ________________________________________
>> From: Stefan Hajnoczi <stefanha@gmail.com>
>> Sent: Tuesday, April 26, 2016 9:31 AM
>> To: tutu sky
>> Cc: qemu-devel@nongnu.org
>> Subject: Re: [Qemu-devel] emulation details of qemu
>>
>> On Sat, Apr 23, 2016 at 06:36:39AM +0000, tutu sky wrote:
>>> I want to know that is it possible to access registers or micro-architectural part of a core/cpu in qemu during run time?
>>
>> Yes.  How and to what extent depends on whether you are using TCG, KVM,
>> or TCI.  QEMU also has gdbstub support so you can single-step execution
>> and access CPU registers.
>>
>> Stefan


--
Alex Bennée