From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LN98N-0000j5-R6 for qemu-devel@nongnu.org; Wed, 14 Jan 2009 12:02:27 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LN98L-0000hS-Mz for qemu-devel@nongnu.org; Wed, 14 Jan 2009 12:02:27 -0500 Received: from [199.232.76.173] (port=43469 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LN98L-0000hC-En for qemu-devel@nongnu.org; Wed, 14 Jan 2009 12:02:25 -0500 Received: from mail2.shareable.org ([80.68.89.115]:42101) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LN98K-0006OB-Qv for qemu-devel@nongnu.org; Wed, 14 Jan 2009 12:02:25 -0500 Received: from jamie by mail2.shareable.org with local (Exim 4.63) (envelope-from ) id 1LN98J-0001su-4K for qemu-devel@nongnu.org; Wed, 14 Jan 2009 17:02:23 +0000 Date: Wed, 14 Jan 2009 17:02:23 +0000 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH][RESEND] Time drift again. Message-ID: <20090114170222.GE6431@shareable.org> References: <20090114115910.GR3267@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090114115910.GR3267@redhat.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org 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