Re: [Xen-ia64-devel] [RFC] MCA handler support for Xen/ia64

[Alex Williamson <alex.williamson@xxxxxx>]

Hi Masaki,

   Thanks for the write-up, generally looks like a good approach to me.
A few comments and questions:

   How do you plan to handle the mismatch between dom0's vCPUs and the
pCPUs reporting errors.  For instance, will all pCPU's CMCs be injected
into dom0 vCPU0?  Will all CPE records be returned from all pCPUs when
dom0 does a SAL_GET_STATE_INFO from vCPU0?  SAL_GET_STATE_INFO_SIZE may
need to return the platform state info size * number of pCPUs to allow
dom0 enough space to save the records.  On big SMP systems we need to
make sure that's not more than can reasonable be allocated in the kernel
by dom0.

   What about clearing error records?  We need to be careful that error
records read by Xen and cleared before being passed to dom0 are volatile
and could be lost if the system crashes or if dom0 doesn't retrieve
them.  It's best to only clear the log after the error record has been
received by dom0 and dom0 issues a SAL_CLEAR_STATE_INFO.  This will get
complicated if we need to clear error records on all pCPUs in response
to a SAL_CLEAR_STATE_INFO on dom0 vCPU0.

   Do you plan to support CMC and CPE throttling in Xen (ie. switching
between interrupt driven and polling handlers under load) and dynamic
polling intervals?

   It may be overly complicated to support CPEI on dom0 (fake MADT
entries, trapping IOSAPIC write, maybe an entirely virtual IOSAPIC in
order to describe a valid GSI for the CPEI, etc...).  Probably best to
start out with just letting dom0 poll for CPE records.  Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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