From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:37602) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T8UnD-000311-HK for qemu-devel@nongnu.org; Mon, 03 Sep 2012 07:26:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T8UnC-0006OI-Lz for qemu-devel@nongnu.org; Mon, 03 Sep 2012 07:26:11 -0400 Received: from thoth.sbs.de ([192.35.17.2]:18737) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T8UnC-0006Ns-CQ for qemu-devel@nongnu.org; Mon, 03 Sep 2012 07:26:10 -0400 Message-ID: <504493CE.8070101@siemens.com> Date: Mon, 03 Sep 2012 13:26:06 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <1346640974-30974-1-git-send-email-mmogilvi_qemu@miniinfo.net> <1346640974-30974-6-git-send-email-mmogilvi_qemu@miniinfo.net> <50446F9A.4070809@web.de> <504479B9.4010801@redhat.com> <5044879D.8000006@siemens.com> <50449061.7080100@redhat.com> In-Reply-To: <50449061.7080100@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 5/5] i8259: fix dynamically masking slave IRQs with IMR register List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Richard Henderson , Matthew Ogilvie , "qemu-devel@nongnu.org" On 2012-09-03 13:11, Paolo Bonzini wrote: > Il 03/09/2012 12:34, Jan Kiszka ha scritto: >>>> Why is this a problem? All of them use IRQ2 for a cascade, and initialize >>>> icw3 to 0x4/0x2 (I checked OpenBIOS, rth's palcode for Alpha, and Linux). >> IRQ2 is already hard-coded in QEMU (we had to patch this for our machine >> emulation, but less in recent versions), that is not the point. I'm >> concerned about the behavioral changes we are discussing here, ie. the >> special handling of cascading interrupt inputs. > > Yeah, it's quite interesting that the behavior isn't mentioned in the > 8259 datasheets. Still in retrospect it's hard to see how it can > possibly work with edge-triggered cascaded inputs. As I said: by avoiding the pattern Matthew generated in his test case. That's not impossible. All the other OSes running fine against out PIC models are proving this. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux