Re: [Bugme-new] [Bug 7495] New: Kernel periodically hangs.

[Adrian Bunk <bunk@stusta.de>]

On Sun, Nov 12, 2006 at 03:16:38PM +0100, Arjan van de Ven wrote:
> 
> > > We KNOW it can't work on a sizable amount of machines.  This is why it
> > > is a config option; you can enable it if YOUR machine is KNOWN to work,
> > > and you get some gains. But it's also understood that it often it won't
> > > work. So any sensible distro (since they have to aim for a wide
> > > audience) disables this option ...
> > 
> > Nowadays, many distributions only ship CONFIG_SMP=y kernels...
> 
> that's a calculated risk on their side (and they know that); they're
> balancing not functioning on a set of machines off against needing more
> kernels.

This might soon affect the majority of Linux users, so it's a case that 
has to be handled...

> > You miss my point.
> > 
> > You said you'd suspect it to be turned off automatic most of the time, 
> > and that's the point I think you might be wrong at.
> 
> it won't be turned off on machines that support dual core processors
> etc, since those DO get validated and designed for APIC use.. even if
> you only stick a single core processor in. So yes you're right, that
> nowadays is a pretty large group. But it's the safe group I guess:)

But if APIC is even used on my more than 1 year old 40 Euro Socket A 
board (AFAIK there have never been dual core Socket A processors, there 
were no Socket A hyperthreading CPUs, it's not an SMP board, and the
VIA KT600 is not an SMP chipset) it's not in what you call "safe group",
and I don't see any reason why my board should behave different in this 
respect from all of the millions of other UP Socket A boards.

Googling show that it could be that your claim "APIC on true UP (no 
Hyperthreading/Dualcore) is a thing no hardware vendor tests (Microsoft 
doesn't use it)" earlier in this thread was wrong. Looking at e.g. [1], 
it seems Windows does use the APIC even on UP.

cu
Adrian

[1] http://www.microsoft.com/whdc/system/sysperf/IO-APIC.mspx

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