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Re: [Xen-devel] [PATCH 1/3] x86: increase precision of x86_platform.get/set_wallclock()

On 05/13/2013 10:56 AM, David Vrabel wrote:
From: David Vrabel <david.vrabel@xxxxxxxxxx>

All the virtualized platforms (KVM, lguest and Xen) have persistent
wallclocks that have more than one second of precision.

read_persistent_wallclock() and update_persistent_wallclock() allow
for nanosecond precision but their implementation on x86 with
x86_platform.get/set_wallclock() only allows for one second precision.
This means guests may see a wallclock time that is off by up to 1

Make set_wallclock() and get_wallclock() take a struct timespec
parameter (which allows for nanosecond precision) so KVM and Xen
guests may start with a more accurate wallclock time and a Xen dom0
can maintain a more accurate wallclock for guests.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
  arch/x86/include/asm/mc146818rtc.h |    4 ++--
  arch/x86/include/asm/x86_init.h    |    6 ++++--
  arch/x86/kernel/kvmclock.c         |    9 +++------
  arch/x86/kernel/rtc.c              |   17 +++++++----------
  arch/x86/lguest/boot.c             |    4 ++--
  arch/x86/platform/efi/efi.c        |   10 ++++++----
  arch/x86/xen/time.c                |   19 ++++++-------------
  include/linux/efi.h                |    4 ++--

Just FYI, David: You missed the vrtc code with this conversion.

I finally got around to pushing my current queue to my public tree and the kbuild robot noticed the build failure (required INTEL_MID config to trigger).

The fix I've queued is here:

Let me know if you have any objection or comments on this.


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