svn commit: r225892 - head/sys/mips/mips

[Adrian Chadd]

On 4 October 2011 10:39, Warner Losh <imp at bsdimp.com> wrote:

>> Is one needed after the mtc0 after StartWaitSkip?
>
> I don't think it matters.  The COP0_SYNC is needed when you want to flush the instruction pipeline so that changes to COP0 don't affect them 'randomly'.  However, in this case.  Either we're setting a bit that's already set, which won't change anything, or we're setting a bit that's clear, which will just delay the delivery of the interrupt a few cycles.  The race where it happens before the wait instruction is handled by the rest of the patch.

That makes sense. I'll try this patch out soon and let you all know how it goes.

Now, hm. How can I easily instrument whether the hardware is actually
spending time in wait or not?

Thanks,


Adrian