From patchwork Tue Aug 18 01:02:29 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Poetzl X-Patchwork-Id: 42223 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n7I12b14028222 for ; Tue, 18 Aug 2009 01:02:37 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751214AbZHRBC3 (ORCPT ); Mon, 17 Aug 2009 21:02:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751793AbZHRBC3 (ORCPT ); Mon, 17 Aug 2009 21:02:29 -0400 Received: from MAIL.13thfloor.at ([213.145.232.33]:44431 "EHLO MAIL.13thfloor.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751005AbZHRBC3 (ORCPT ); Mon, 17 Aug 2009 21:02:29 -0400 Received: by mail.13thfloor.at (Postfix, from userid 1001) id CA8713C205; Tue, 18 Aug 2009 03:02:29 +0200 (CEST) Date: Tue, 18 Aug 2009 03:02:29 +0200 From: Herbert Poetzl To: kvm@vger.kernel.org, qemu-devel@nongnu.org Cc: Avi Kivity Subject: Re: i8259 defaults wrong? Message-ID: <20090818010229.GA6083@MAIL.13thfloor.at> Mail-Followup-To: kvm@vger.kernel.org, qemu-devel@nongnu.org, Avi Kivity References: <20090817022024.GE1025@MAIL.13thfloor.at> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <20090817022024.GE1025@MAIL.13thfloor.at> User-Agent: Mutt/1.5.11 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org >On Mon, Aug 17, 2009 at 04:20:24AM +0200, Herbert Poetzl wrote: >> >> Greetings! >> >> looking at the i8259 implementation found in qemu >> as well as in the in-kernel kvm implementation, I >> see that on pic_reset() special_fully_nested_mode >> is set to zero, but the intel(r) 8259A manual says >> on page 15: >> >> Fully Nested Mode >> >> This mode is entered after initialization unless >> another mode is programmed. >> >> any comments are appreciated, a patch should be >> trivial, but I'd gladly submit one if requested. > > Well, does the BIOS set fully nested mode on reset? no idea, but as far as I tested, it doesn't matter for Linux guests, but makes some other operating systems - which seem to heavily rely on this default (e.g. OpenStep, darwin) - work like expected. > If not, a kvm change is difficult, since the bios > and kvm are updated independently. nevertheless IMHO it should be fixed ASAP, and the required change is trivial, i.e. only a single line in the kvm/qemu code needs to be changed to make it work correctly (see patches below) best, Herbert please CC me as I'm not subscribed to either list ; fix i8259 reset behaviour ; qemu/kvm (outside the kernel) ; >> TIA, >> Herbert --- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- ./hw/i8259.c.orig 2009-08-12 19:45:45.000000000 +0200 +++ ./hw/i8259.c 2009-08-17 03:48:15.000000000 +0200 @@ -295,7 +295,7 @@ static void pic_reset(void *opaque) s->init_state = 0; s->auto_eoi = 0; s->rotate_on_auto_eoi = 0; - s->special_fully_nested_mode = 0; + s->special_fully_nested_mode = 1; s->init4 = 0; s->single_mode = 0; /* Note: ELCR is not reset */ ; fix i8259 reset behaviour ; kvm (inside the kernel) --- ./arch/x86/kvm/i8259.c.orig 2009-06-11 17:12:23.000000000 +0200 +++ ./arch/x86/kvm/i8259.c 2009-08-18 02:50:00.000000000 +0200 @@ -279,7 +279,7 @@ void kvm_pic_reset(struct kvm_kpic_state s->init_state = 0; s->auto_eoi = 0; s->rotate_on_auto_eoi = 0; - s->special_fully_nested_mode = 0; + s->special_fully_nested_mode = 1; s->init4 = 0; }