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Re: [Qemu-devel] Buggy wfi support for ARM user
From: |
Laurent Desnogues |
Subject: |
Re: [Qemu-devel] Buggy wfi support for ARM user |
Date: |
Sun, 8 Jun 2008 18:45:09 +0200 |
On Sun, Jun 8, 2008 at 6:38 PM, Blue Swirl <address@hidden> wrote:
> On 6/8/08, Laurent Desnogues <address@hidden> wrote:
>> >> I propose that for user mode this instruction be considered
>> >> as a NOP. Any thoughts?
>> >
>> > Allowing usermode to issue WFI sounds like a bug.
>>
>> Here is a proposal that makes WFI no-ops for user mode emulation.
>> Comments welcome, especially as I am not used to send patches :)
>
> Generally, the config-host.mak part should be suppressed in patches.
Sorry about that, I used make clean instead of distclean.
> I don't know about this WFI case or even much of ARM at all, but if
> enabling WFI is controversial, maybe it could be implemented as a CPU
> feature so that it is disabled by default.
It's not controversial I think. It's just that it's architected to be
executable by user processes. However it only makes sense
if a process can receive interruptions which is not really the
case for qemu user mode emulation. This instruction is used
to reduce power in idle loops.
Laurent
wfi.patch
Description: Text Data