Re: mutex vs. local irqs (Was: 2.6.18 -mm merge plans)

Benjamin Herrenschmidt
2006-06-08T00:31:50Z

> a better solution would be to install boot-time IRQ vectors that just do
> nothing but return. They dont mask, they dont ACK nor EOI - they just
> return. The only thing that could break this is a screaming interrupt,
> and even that one probably just slows things down a tiny bit until we
> get so far in the init sequence to set up the PIC.

Changing vectors on the fly is hard on some platforms.... We could
change our toplevel ppc_md.get_irq() on powerpc, but we still to do
something about decrementer interrupts.
A screaming level interrupt will lockup the machine at least on some
platforms.

The problem with all those approaches is that they require changes to
all archs interrupt handling to make the situation safe vs. mutexes...

I still don't think where is the suckage in just not hard-enabling in
the mutex debug code...

Ben.