Re: [Qemu-devel] [PATCH v8 00/16] gdbstub: support for the multiprocess extension

[Luc Michel]

On 1/4/19 4:12 PM, Peter Maydell wrote:
> On Fri, 7 Dec 2018 at 09:01, Luc Michel <address@hidden> wrote:
>> This series adds support for the multiprocess extension of the GDB
>> remote protocol in the QEMU GDB stub.
>>
>> This extension is useful to split QEMU emulated CPUs in different
>> processes from the point of view of the GDB client. It adds the
>> possibility to debug different kind of processors (e.g. an AArch64 and
>> an ARMv7 CPU) at the same time (it is not possible otherwise since GDB
>> expects an SMP view at the thread granularity.
> 
> I've applied this patchset to target-arm.next, thanks.
> (I fixed up a few checkpatch nits about block comment style.)
Thanks!

> 
>> To test this patchset, you can use the following commands:
>>
>> (Note that this requires a recent enough GDB, I think GDB 7.2 is OK.
>> Also, it must be compiled to support both ARM and AArch64 architectures)
>>
>> Run QEMU: (-smp 6 in xlnx-zcu102 enables both cortex-a53 and cortex-r5
>> CPUs)
>>
>> qemu-system-aarch64 -M xlnx-zcu102 -gdb tcp::1234 -S -smp 6
>>
>> Run the following commands in GDB:
>>
>> target extended :1234
>> add-inferior
>> inferior 2
>> attach 2
>> info threads
> 
> This seems a bit clumsy -- is it just the limitations of
> gdb here? I was expecting that just connecting to the
> remote would cause gdb to interrogate it and attach to
> all the inferior processes that it had.
AFAIK this is a "limitation" of GDB. In QEMU context it seems like a
limitation, but when you are connecting to a remote gdbserver that
exposes all the processes currently running on an OS, you probably don't
want to attach them all automatically.

Luc

> 
> thanks
> -- PMM
>