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Date: Wed, 21 Jan 2009 19:24:40 +0000
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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Subject: Re: [Qemu-devel] ppc emulation and interrupts
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To: qemu-devel@nongnu.org

Lennart Sorensen wrote:

> On Wed, Jan 21, 2009 at 11:49:10AM +0000, Stefano Stabellini wrote:
>> Hi all,
>> one of the recent problems, noticed after the displaystate change,
>> affects ppc emulation only and is due to the fact that none on ppc
>> emulation is issuing any interrupt request of the CPU_INTERRUPT_EXIT
>> kind if the gui timer is disabled.
>> Hence qemu never leaves the loop in cpu-exec.c:cpu_exec.
>> If the gui timer is enabled qemu is able to leave the loop because the
>> condition (interrupt_request & CPU_INTERRUPT_EXIT) is true when the
>> timer is triggered.
>> I think this is a problem with the ppc emulation but if you ppc guys
>> need the gui timer to be always on, I can arrange for it to be.
>> Regards,
> 
> So does this explain why vnc runs fast and sdl runs slow?


No, this bug prevents qemu from working when only vnc is enabled.

 
> Even with the latest patches, sdl is still slow for ppc emulation.  Not
> using much cpu either of course.
> 


I'll investigate more on this.
As I said before, sdl shouldn't be noticeable slower now, unless you are
using remote X.
I have just tried debian ppc and I get similar performances using vnc
(localhost) or sdl (local X server).