Re: [Qemu-devel] [patch 1/2] qemu: sem/thread helpers

[Marcelo Tosatti]

On Wed, Mar 11, 2009 at 04:48:01PM +0000, Paul Brook wrote:
> > +QemuSem qemu_sem;
> 
> It's entirely unclear what is actually protected by the semaphore.

Everything at the moment.

> What exactly does the IO thread do? AFAICS device MMIO is still run from 
> within the CPU thread. Device code is not threadsafe (and probably never will 
> be), so you can't run any of the device callbacks in the IO thread either. 
> Doesn't seem like there's a lot left for it to do...

There are things which can run in parallel. VNC dirty update, read()'ing
of data into QEMU, for two examples.