Re: [Xen-devel] noirqdebug_setup() in arch/i386/kernel/setup-xen.c

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 7 Apr 2006, at 10:00, Jan Beulich wrote:

> Can anyone explain why i386 calls noirqdebug_setup() unconditionally, 
> while x86-64 doesn't? I believe this is the reason
> why we have been seeing spurious interrupt reports only on 64-bits so 
> far.
> What was this supposed to suppress originally? Is this still 
> applicable? It would seem to me that hiding problems in
> this area is rather undesirable...
It's disabled to handle the case where a shared IRQ line is shared 
across multiple driver domains. In that case, if one domain's device is 
busy then both domains will get interrupt notifications, but the 
non-busy driver domain will think that it's receiving spurious 
interrupts (since it doesn't see IRQ_HANDLED from the busy device 
driver ISR, since it's running in a different driver domain).
The above scenario is reasonably rare, and especially if there are 
currently irq problems I think we should stop asserting noirqdebug 
automatically, at least for now in xen-unstable.
 -- Keir


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel