Re: [PATCH] Stall semantics

[Matthew Wilcox <willy-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>]

On Wed, Oct 01, 2003 at 10:27:04AM -0700, Nate Lawson wrote:
> You're assuming the AML mistake is made both ways.  If it is uniformly
> made one way, it's easy to work around correctly.

Actually, I assume that AML writers are idiots who can't read the spec.
They almost certainly want to stall for 2 seconds.  The fact that they
can't doesn't stop them trying.

> > I think the current ACPI behaviour is probably adequate -- accommodate
> > incopetent BIOS writers up to a point, then sleep, and damn them anyway.
> 
> It damns us OS vendors a different way in that we get unacceptably long
> idle spin loops on some machines.  Spinning for 1000 us is not correct any
> way you interpret the standard.

You have a machine which isn't able to stall for 1 millisecond?
Many drivers do stall for that much, and more.  Grepping the linux-2.6
tree shows a lot of drivers calling mdelay() -- tulip, e1000, symbios,
aic7xxx, radeon, mach64, ohci, uhci, ide, ...

One gem..
./drivers/ide/pci/pdc202xx_new.c:       mdelay(2000);   /* 2 seconds ?! */

I don't think a 1ms stall is exceptional, or even remarkable.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk


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