Messages in this thread | | | From | (Eric W. Biederman) | Date | Fri, 10 Jul 2009 13:29:46 -0700 | Subject | Re: [PATCH v3] enable x2APIC without interrupt remapping under KVM |
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Suresh Siddha <suresh.b.siddha@intel.com> writes:
> On Wed, 2009-07-01 at 17:17 -0700, Eric W. Biederman wrote: >> Suresh Siddha <suresh.b.siddha@intel.com> writes: >> > Among number of experiments you have tried in the past to fix this, have >> > you tried the experiment of explicitly clearing the remoteIRR by >> > changing the trigger mode to edge and then back to level. >> > >> > Is there a problem with this? >> >> The problem I had wasn't remoteIRR getting stuck, but the symptoms >> were largely the same. I did try changing the trigger mode to edge >> and back and that did not unstick the ioapic in all cases. >> > > I did some experiments locally here yesterday and on my old ICH5 based > system, I couldn't reset the remoteIRR by changing the trigger mode to > edge and then back to level. > > However what worked was an explicit eoi to the io-apic using the > respective vector. > > I guess we need to try both the things based on perhaps io-apic version > etc.
In part the deep problems I ran into was something other than RemoteIRR. If it was something as simple as the ioapic being in a documented state I would have kept looking. At the very least the RemoteIRR bit was not set in some of the cases I encountered.
> But what I am nervous about is, did you try both these things aswell and > still saw stuck interrupts?
Yes. The work arounds were in the code so I tried them.
> I will cleanup my code and post it, so that we can try on different > systems. If this still doesn't work on certain HW platforms, atleast our > experiments of what works and what doesn't work and on what platforms > will be documented on the web.
Sounds reasonable. My apologies for the long delayed reply. I want to work on this but I have higher priorities.
Eric
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