Re: [Xen-devel] [RFC] x86: restore PCI SERR NMI forwarding to Dom0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.01.13 at 12:26, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
wrote:
> On Thu, 17 Jan 2013, Jan Beulich wrote:
>> c/s 22949:54fe1011f86b removed the forwarding of NMIs to Dom0 when they
>> were caused by PCI SERR. NMI buttons as well as BMCs (like HP's iLO)
>> may however want such events to be seen in Dom0 (e.g. to trigger a
>> dump).
>> 
>> I'm therefore suggesting to restore most of the functionality which
>> named c/s removed (adjusted for subsequent changes, and adjusting the
>> public interface to use the modern term, retaining the old one for
>> backwards compatibility).
> 
> Allowing the possibility of injecting these events in Dom0 might be a
> good idea (dom0 just ignores PCI SERR anyway if I recall correctly).
> However the default for opt_nmi in Xen is "fatal", so if I am not
> mistaken you are changing the default Xen behaviour from ignore PCI
> SERR to break down on PCI SERR. I don't think that's a good idea.

#ifdef NDEBUG
static char __read_mostly opt_nmi[10] = "dom0";
#else
static char __read_mostly opt_nmi[10] = "fatal";
#endif

I.e. debug builds would die, but "normal" builds wouldn't. If the
former is a problem, it's so not only for PCI SERR imo (and would
need fixing here rather than in the patch I sent).

Jan


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