From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "Pasi Kärkkäinen" <pasik@iki.fi>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Drew Jones <drjones@redhat.com>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: vsyscall support in 2.6.{32,33}
Date: Tue, 21 Sep 2010 10:31:55 -0700 [thread overview]
Message-ID: <4C98EC0B.3090005@goop.org> (raw)
In-Reply-To: <20100921130910.GQ2804@reaktio.net>
On 09/21/2010 06:09 AM, Pasi Kärkkäinen wrote:
> On Tue, Sep 21, 2010 at 02:49:17PM +0200, Paolo Bonzini wrote:
>> Besides the obvious fact that the required hypercall is not supported by
>> any released hypervisor, is there any other reason why the xen vsyscall
>> code is not in the pvops/stable-2.6.{32,33}.x branches?
>>
>> Thanks!
>>
> I guess Jeremy didn't remember to merge it yet? :)
> Or is there some problem with it?
>
The main problem is that I'm not sure that the Xen clock algorithm can
give strict enough monotonicity for usermode use (ie, can't meet the
expected behaviour of clock_gettime()), and its not at all clear how to
fix it. I could prevent non-monotonicity within one process, but not
between processes.
J
prev parent reply other threads:[~2010-09-21 17:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-21 12:49 vsyscall support in 2.6.{32,33} Paolo Bonzini
2010-09-21 13:09 ` Pasi Kärkkäinen
2010-09-21 17:31 ` Jeremy Fitzhardinge [this message]
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