Bug#258061: ACPI initialization hangs on Compaq Presario 2100

["Francesco P. Lovergine" <frankie@debian.org>]

On Fri, Sep 03, 2004 at 12:15:00PM -0300, Bruno Diniz wrote:
> When the patch you mentioned was not applied, I could make it work
> with any kernel version by simply adding a 'disable_APIC_timer' in the
> beginning of acpi_bus_init, and a 'enable_APIC_timer' in the end of
> this function.
> 
> By the way, what is Local APIC for? What do I lose having Local APIC disabled?

Find it in kernel sources:

  A local APIC (Advanced Programmable Interrupt Controller) is an
  integrated interrupt controller in the CPU. If you have a single-CPU
  system which has a processor with a local APIC, you can say Y here to
  enable and use it. If you say Y here even though your machine doesn't
  have a local APIC, then the kernel will still run with no slowdown at
  all. The local APIC supports CPU-generated self-interrupts (timer,
  performance counters), and the NMI watchdog which detects hard lockups.

The processor local APIC is of fundamental importance in SMP and RT 
environments to manage correctly I/O and and internal interrupts, timing
and so. You can live without on uniprocessor systems. 
P5 did not have lapic indeed. If I remember correctly first multi-proc
board had PPro which was the first with a lapic...

Anyway tnis is the 'missing pointer' for the issue on LKML:

http://www.ussg.iu.edu/hypermail/linux/kernel/0401.2/1525.html

And it seems simply missing in debian sources. So the fix by Christopher 
was different (and unuseful for this issue).

> 
> On Fri, 3 Sep 2004 09:44:07 +0200, Francesco P. Lovergine
> <frankie@debian.org> wrote:
> > On Thu, Sep 02, 2004 at 11:00:50PM -0300, Bruno Diniz wrote:
> > > Is there a problem with the idea of "turn off APIC timer before ACPI
> > > initialization and then turn back on after ACPI initialization
> > > finishes"? This is exactly what the tiny patch I've sent does. I would
> > > agree that 'nolapic' boot param "solves" the problem, but IMHO the
> > > idea above is clearer and works perfectly.
> > >
> > 
> > The idea is clear, but that patch does not work on the 2100 I tried.
> > It was already implemented in current 2.6.8 AFAIK and it has exactly
> > the same problem of hang up.
> > 
> > > Thanks,
> > >
> > > Bruno.
> > >
> > > On Thu, 2 Sep 2004 12:52:35 +0200, Francesco P. Lovergine
> > > <frankie@debian.org> wrote:
> > > > Ok I verified that:
> > > >
> > > > * This issue is yet valid for current 2.6.8 with acpi=on
> > > > * It's valid for 2.4 series up to 2.4.27 with acpi=on
> > > > * Patch proposed in 2.6.8 does not solve the issue, so it can be removed.
> > > >
> > > > The only workaround in all cases is the 'nolapic' boot param.
> > > >
> > > > --
> > > > Francesco P. Lovergine
> > > >
> > > >
> > 
> > -- 
> > Francesco P. Lovergine
> > 
> 
> 
> 
> -- 
> Bruno Diniz de Paula

-- 
Francesco P. Lovergine