Re: [RFC] ACPI power-off on P4 HT

[Pavel Machek <pavel@ucw.cz>]

Hi!

> as I previously said, the patch I sent which fixes the poweroff on my VAIO is
> not enough to shut down the supermicro P4 HT. So I borrowed some code from
> machine_restart() to try to :
>   - disable APIC  => was not enough, but I must retry on the VAIO
>   - stop the second CPU => was not enough either
>   - bounce on boot_cpu and stop the others => it did work.
> 
> So I think that ACPI is not SMP-proof nor HT-proof on some hardware. My new
> problem is that I feel like the code I have included in acpi_power_off() to
> do this is a bit too much x86 specific, so I'd like to move this to
> arch/i386/kernel/process.c with all the rest, but I don't know how to cut
> this. I think that a general function such as machine_prepare_shutdown() or
> something like this would be useful and could be shared by both ACPI and
> machine_restart(). It would basically to everything that is needed in such
> a case :
>   - on SMP, bounce on boot_cpu, then halt the current CPU if != boot_cpu
>   - on SMP, stop all other CPUs
>   - on UP, disable IOAPIC
>   - disable local APIC
> 
> I suspect that this function would be useful for some suspend cases, but I'm

Well, to be usefull for suspend, also "opposite" code would be
neccessary (enable apic, restart other cpus).
And yes, that would be very welcome.
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