Re: Horrible ordeals with ACPI, APIC and HIGHMEM (2.6.0-test* and -ac kernels)

[Chris Wright <chrisw@osdl.org>]

* Martin Aspeli (optilude@gmx.net) wrote:
> On Thu, 9 Oct 2003 14:05:23 -0700, Chris Wright <chrisw@osdl.org> wrote:
> 
> > Which 2.6.0-test kernels?  Have you tried 2.6.0-test7?  A fix for this
> > type of problem went into -test7.
> 
> Sadly, yes. My most recent and most comprehensive tests (today) were with 
> the -test7 kernel. Could you give me some details as to what the fix is 
> supposed to do and why it may not work?

fixes acpi pci link allocation which could pick a bad irq causing an
interrupt storm.  typical symptom was hang on boot.  

If you see:

ACPI: PCI Interrupt Link [LNKA] (IRQs 3 4 6 7 10 *11 12)
...
ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 6

where the link is not enabled at the current setting (11 in this case,
marked by *), you might experience this kind of hang.

> Also, I'd still be interested to know - what is "events/0"?

events/0 is a kernel thread (keventd) used for scheduling work into process
context.  acpi uses keventd for handling acpi events, for example, so
runaway apci events will cause events/0 to chew up cpu.

> And why do 
> things run like a 286 when I enable HIGHMEM? 

I don't know, it shouldn't.

thanks,
-chris
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