[Xen-devel] [PATCH RFC v2 0/2] Fix RTC noack issues

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This series allows the toolstack to choose (by way of XenStore platform flags)
whether the domain is expecting to make use of RTC mode noack performance
optimisations.

It also switches the implict default back to rtc_mode_strict, which is the
safe default for Xen to have.

This fixes a longstanding regression in Win2k3SP2 only where its access
pattern causes it to fall into an infinite loop reading RTC RegC.

Questions for thought:

 * Does it make sense to allow customisation of ACPI_WAET_TIMER_ONE_READ ?
   There is no sitation where an admin should turn it off.

 * I believe this is safe wrt migrations, but am not certain enough to say for
   sure.  This is a critical point, as the bad default (and regression) has
   been in Xen since late in the Xen-4.3 development cycle.


---

Changes in v2:
 * Remove the hypervisor enum and replace with a formal ABI in params.h
 * Leave PM timer reads alone and accept fewer options for "true"


-- 
1.7.10.4


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