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From: Jamie Lokier <jamie@shareable.org>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH][RESEND] Time drift again.
Date: Wed, 14 Jan 2009 17:02:23 +0000	[thread overview]
Message-ID: <20090114170222.GE6431@shareable.org> (raw)
In-Reply-To: <20090114115910.GR3267@redhat.com>

Gleb Natapov wrote:
>  After my last patch to fix interrupt coalescing was rejected
> on the basis that it is too intrusive we decided to make the
> fix much more localized and only fix the problem for RTC time
> source. Unfortunately it is impossible to fix the problem entirely
> inside RTC code like Andrzej proposed since Windows reads RTC
> register C more then once on each time interrupt so it is impossible
> to count reliably how many interrupt windows actually handled.
> Proposed solution is localized to I386 target and is disabled by
> default. To enable it "-rtc-td-hack" flag should be used.

I truly don't understand why the time correction is done by arcane
guest-specific details like counting register reads, making interrupts
behave different from real hardware, and only correcting guests which
use particular clock sources - instead of simply warping virtual time
(in all the places it's used) which might actually work on all targets
and all guest OSes.

I don't remember anybody responding to that suggestion.
Was it a silly one?

-- Jamie

  reply	other threads:[~2009-01-14 17:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-14 11:59 [Qemu-devel] [PATCH][RESEND] Time drift again Gleb Natapov
2009-01-14 17:02 ` Jamie Lokier [this message]
2009-01-14 17:34   ` Avi Kivity
2009-01-15 13:53   ` Marcelo Tosatti
2009-01-15 20:12 ` Anthony Liguori

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