Re: Fixing MTRR smp breakage and suspending sysdevs.

[Dmitry Torokhov]

On Tuesday 26 October 2004 10:17 pm, Nigel Cunningham wrote:
> Hi.
> 
> On Wed, 2004-10-27 at 13:20, Dmitry Torokhov wrote:
> > On Tuesday 26 October 2004 09:48 pm, Li, Shaohua wrote:
> > > >One thing I have noticed is that by adding the sysdev suspend/resume
> > > >calls, I've gained a few seconds delay. I'll see if I can track down
> > > the
> > > >cause.
> > > Is the problem MTRR resume must be with IRQ enabled, right? Could we
> > > implement a method sysdev resume with IRQ enabled?
> > 
> > If I understand correctly the point of classifying device as sysdev is
> > that it (device) is essential for the system and must be suspended last
> > and resumed first, presumably with interrupts off. IRQ controller comes
> > to mind...
> 
> Yes, but could we not do something like the process with regular
> devices. ie a call with interrupts disabled and then a similar call with
> interrupts enabled?
> 

Yes, re-reading the parent post it seems that's what required for ACPI.
Doing a pass with IRQ ON for regular devices, then IRQ OFF, then IRQ on
again for sysdevs and then again with IRQ off. Man, that's getting messy...

Well, I understand that ACPI is using semaphore and a GFP_KERNEL, but what
is the problem with MTRR? I understand that they should be set with IRQ
off but I highly doibt that enabling IRQ at the end is a requirement.
I think what is described in the commnet is rather a "normal flow of events".

-- 
Dmitry
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