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[Xen-devel] [RFC PATCH] revive VCPUOP_register_time_memory_area

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Subject: [Xen-devel] [RFC PATCH] revive VCPUOP_register_time_memory_area
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Thu, 03 Feb 2011 18:14:28 +0100
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Hi all,

the attached patch tries to revive the support for userspace vcpu_time_info. Writing the information is done after context switch to prevent the memory corruption that led to the disabling of the hypercall.

The patch also fixes the write of version_update_begin(_u.version) into the userspace vcpu_time_info.

A while ago, Jeremy wrote that he was "not sure that the Xen clock algorithm can give strict enough monotonicity for usermode use". Has anybody else ever put some thought into this, and maybe shared (or not shared) his worries?

The patch is mostly untested because Xen 4.1 fails to boot the (non-pvops) dom0 kernels I have around; a very similar patch _was_ tested though and worked. :)

Paolo

Attachment: vcpu-rfc.patch
Description: Text document

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