Re: [PATCH 45/79] [PATCH] fix apic acking of irqs

[Glauber Costa]

Maciej W. Rozycki wrote:
> On Wed, 19 Mar 2008, Glauber de Oliveira Costa wrote:
>
> > EOI is a write-only register. Using write around will have the effect
> > of reading it, which will make all subsequent reads of the ESR register
> > to return an error code. It was unnotices for quite a while because main sources
> > of reading the ESR register where done prior to apic interrupt enabling.
>
>  Are you sure this actually triggers for APIC chips affected by the 
> erratum in question?  And please note that for them the effect of two 
> consecutive writes will be much more disastrous than setting a bit in the 
> ESR register.
>
>   Maciej

I'm not _sure_, but I can't find anything in the errata list that states 
otherwise. It would be great that anyone has such a system to test it. 
But with the current conditions, it will break bootup code. In case it 
is really a problem, we'd need to make a special case for that.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/