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[Xen-devel] [PATCH] Make HPET device model paranoid to counter wrap

  • To: "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • Date: Tue, 21 Oct 2008 09:58:39 +0100
  • Cc: Peter Johnston <Peter.Johnston@xxxxxxxxxx>
  • Delivery-date: Tue, 21 Oct 2008 01:59:15 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AckzWzWJc+3uGp9OEd2v1AAX8io7RQ==
  • Thread-topic: [PATCH] Make HPET device model paranoid to counter wrap

Changing the hpet periodic timers to use vpt periodic timers means there is
no real reason to have a hpet callback at all.  However, the value of the
comparator is now computed when it is read (which is rarely), based on the
difference between the current time and the last comparator value.  This
works unless the current time has wrapped and passed the comparator
completely at least once since it was last read.  This patch reimplements
the hpet callback so that the comparator is updated on every timer
expiration (for a running timer).  It is probably not needed but better safe
than sorry.
Signed-off-by: Peter Johnston <peter.johnston@xxxxxxxxxx>

Attachment: hvm-hpet-paranoid
Description: Binary data

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