[haiku-development] Re: [patch] x86: AMD C1E with no ARAT(Always Running APIC Timer) idle support

Dear List,

On Sat, Apr 7, 2012 at 4:21 PM, Yongcong Du <ycdu.vmcore@xxxxxxxxx> wrote:

> Dear list,
>
> In my gsoc proposal, I mentioned the local APIC timer issue--APIC timers
> may be shutdown when entering deeper C-States. For intel CPUs, this issue
> will only happen after we adds the so called cpuidle support. But for AMD
> CPUs, I think we already have this problem. Please refer to
> http://dev.haiku-os.org/ticket/8111 for details. But I'm not sure whether
> the root cause of #8111 is the APIC issue.
>
> Hi Luposian,
> Would you please help to try the patch?
>
> Thanks in advance,
> Yongcong
>
> The patch is attached. Here is the copied commit msg.
>
> commit 694ea35b57f0e2d11b5b567e46baff10e488ae30
> Author: Yongcong Du <ycdu.vmcore@xxxxxxxxx>
> Date:   Sat Apr 7 16:07:29 2012 +0800
>
>     x86: AMD C1E with no ARAT(Always Running APIC Timer) idle support
>
>     AMD C1E is a BIOS controlled C3 state. Certain processors families
>     may cut off TSC and the lapic timer when it is in a deep C state,
>     including C1E state, thus the cpu can't be waken up and system will
> hang.
>
>     This patch firstly adds the support of idle selection during boot. Then
>     it implemnts amdc1e_noarat_idle() routine which checks the MSR which
>     contains the C1eOnCmpHalt (bit 28) and SmiOnCmpHalt (bit 27)  before
>     executing the halt instruction, then clear them once set.
>
>     This patch may fix http://dev.haiku-os.org/ticket/8111
>
>     References:
>     BIOS and Kernel Developer's Guide for AMD NPT Family 0Fh Processors
>


The real fix should be switch to another reliable timer before hlt
instruction. But this need more haiku timer subsystem changes. I put this
into goal after gsoc.

The idle routine selection support is also needed by my cpuidle project. To
achieve this goal,  we can change the global arch_cpu_idle() as a function
pointer or just do as my patch does. The former is cleaner and no function
call overhead, the later doesn't impact other architecture. My question is
which way do you prefer?

Thanks

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