[Qemu-devel] Let event loop use non-default GMainContext

[Qemu-devel] Let event loop use non-default GMainContext

[Eva Chen]

Hello,

It seems that AIO use global default GMainContext by
*g_main_context_default()*.
I want to replace all default GMainContext into another GMainContext by
*g_main_context_new()*, but I have no idea when and where to add
*g_main_context_new()*.

It should be only created new GMainContext once, then others use this new
GMainContext.
But it's hard to create a global variable that will not cause redefine
during make

Is there any suggestion which data structure is suitable for adding a
GMainContext?
or is there any advice for replacing default GMainContext?

The reason for replacing default GMainContext is that I simultaneously run
two qemu, called A and B, in threads. However, these two QEMU using the
same default GMainContext causes A QEMU to handle the event from B QEMU,
and run B's handler instead of A's handler.

I will be grateful for any help, thanks.

Sincerely,
Eva



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Re: [Qemu-devel] Let event loop use non-default GMainContext

[Stefan Hajnoczi]

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On Mon, Apr 16, 2018 at 04:52:34PM +0800, Eva Chen wrote:
> The reason for replacing default GMainContext is that I simultaneously run
> two qemu, called A and B, in threads. However, these two QEMU using the
> same default GMainContext causes A QEMU to handle the event from B QEMU,
> and run B's handler instead of A's handler.

I think you will hit many other issues if you try to run two instances
of QEMU within a single process.  There have been several efforts to
simulate heterogenous systems (e.g. different CPUs as part of one
computer).  Some of them run multiple QEMU instances and communicate
between the processes.

Before going further, have you looked into existing work on emulating
heterogenous systems under QEMU?

Stefan

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Re: [Qemu-devel] Let event loop use non-default GMainContext

[Stefan Hajnoczi]

On Sat, Apr 21, 2018 at 11:29 AM, Eva Chen <debby83729@gmail.com> wrote:
> Thanks for your reply.
>
> Actually, I don't know there is existing work on emulating heterogeneous
> system under QEMU. The only work I know is that QEMU has implemented
> multicore in one QEMU process. But what I want to do is to simulate two
> heterogeneous cpu core at the same time.
> May I ask if you know any related work?

I'm not familiar with the work that has been done, but here are two
starting points you may find interesting:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1007.285&rep=rep1&type=pdf

https://lists.gnu.org/archive/html/qemu-devel/2015-10/msg00171.html

Stefan