Re: [PATCH] restore sysenter MSRs at resume

[Linus Torvalds]

On Wed, 7 May 2003 [e-mail] wrote:
> 
> We don't do apm suspend/resume on SMP, so this is no different from the
> current situation. I don't know if acpi does it or not.

Well, the thing is, if we ever do want to support it (and I suspect we 
do), we should have the infrastructure ready. It shouldn't be too hard to 
support SMP suspend in a 2.7.x timeframe, since it from a technology angle 
looks like simply hot-plug CPU's. Some of the infrastructure for that 
already exists.

But I seriously doubt we want to do CPU hot-plug as a device driver. 
Having a hook in place for it in the arch directory will make it easyish 
to add once we integrate all the other hotplug code (which is very 
unlikely in the 2.6.x timeframe).

> I could probably get away with simply having apm.c invoke the C code
> in suspend.c, which does restore the SYSENTER MSRs. suspend.c itself
> doesn't seem to depend on the SOFTWARE_SUSPEND machinery, but
> suspend_asm.S does.
> 
> Does that sound reasonable?

Sounds reasonable to me. In fact, it looks like it really already exists
as the current "restore_processor_state()" thing.

In fact, that one already _does_ call "enable_sep_cpu()", so what's up?

		Linus