Re: [patch 2/2] x86: arch specific support for remapping HPET MSIs

Ingo Molnar
2009-08-10T18:52:19Z

* Suresh Siddha <suresh.b.siddha@intel.com> wrote:

> On Sat, 2009-08-08 at 08:12 -0700, Ingo Molnar wrote:
> > * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> >
> > > x86 arch support for remapping HPET MSI's by associating the HPET
> > > timer block with the interrupt-remapping HW unit and setting up
> > > appropriate irq_chip
> >
> > interesting. This means we'd materially utilize the irq-remapper
> > not just on relatively obscure, virtualization related setups,
> > but also in the native x86 bootup mode, on all (hpet+remap
> > capable) Linux systems?
>
> Ingo, For native linux kernel, interrupt-remapping allows simple
> and reliable irq migration from the process context (in addition
> to its need for supporting cpu's capable of x2apic). And as such
> solves the issues we had in the past with cpu hotplug and irq
> migration.

It's something much more directly useful than a fix for race
conditions, and it would be used in a broader range of hardware
than x2apic. (Not to denounce its other uses - i was just upbeat
about it getting even more mainstream use.)

Ingo