From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41141) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QFkGq-0004E5-7k for qemu-devel@nongnu.org; Fri, 29 Apr 2011 05:46:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QFkGp-0002a6-CC for qemu-devel@nongnu.org; Fri, 29 Apr 2011 05:45:56 -0400 Received: from mx3-phx2.redhat.com ([209.132.183.24]:46387) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QFkGo-0002Zy-W7 for qemu-devel@nongnu.org; Fri, 29 Apr 2011 05:45:55 -0400 Date: Fri, 29 Apr 2011 05:45:51 -0400 (EDT) From: Ulrich Obergfell Message-ID: <722267231.277846.1304070351482.JavaMail.root@zmail07.collab.prod.int.phx2.redhat.com> In-Reply-To: <4DB9EF36.1010803@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 1/5] hpet 'driftfix': add hooks required to detect coalesced interrupts (x86 apic only) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: aliguori@us.ibm.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, gcosta@redhat.com, Blue Swirl , avi@redhat.com > On 2011-04-28 20:51, Blue Swirl wrote: >> On Thu, Apr 28, 2011 at 5:24 PM, Ulrich Obergfell wrote: >>> 'target_get_irq_delivered' and 'target_reset_irq_delivered' contain >>> entry addresses of functions that are utilized by update_irq() to >>> detect coalesced interrupts. apic code loads these pointers during >>> initialization. >> >> I'm not so happy with this approach, but probably then the i386 >> dependencies can be removed from RTC and it can be compiled only once >> for all targets. > > This whole series is really the minimalistic approach. The callbacks > defined here must remain a temporary "shortcut". Just like proper > abstraction of periodic tick compensation for reuse in other timers has > to be added later on. And the limitation to edge-triggered legacy HPET > INTs has to be removed. Since QEMU doesn't have a generic infrastructure to track interrupt delivery, I decided to reuse something that is currently available. The only mechanism that I'm aware of is the one that is utilized by RTC code ('rtc_td_hack'), i.e. apic_get_irq_delivered() etc. The changes that would be introduced by part 1/5 and part 4/5 of this patch series could be replaced if a generic infrastructure to track interrupt delivery becomes available. Regards, Uli