From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH 1/4] x86/hvm: Centralize and simplify the RTC IRQ logic. Date: Thu, 28 Mar 2013 19:57:18 +0000 Message-ID: References: <20130328153007.GM23950@ocelot.phlegethon.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130328153007.GM23950@ocelot.phlegethon.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Tim Deegan , Jan Beulich Cc: keir@xen.org, suravee.suthikulpanit@amd.com, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 28/03/2013 15:30, "Tim Deegan" wrote: >> And it further doesn't help that we don't even have >> vioapic_irq_negative_edge() as counterpart to >> vioapic_irq_positive_edge(), i.e. we're not even capable of truly >> delivering an active low IRQ. > > I get the impression that the xen IRQ model doesn't actually include a > concept of 'active high' vs 'active low', just 'asserted' or 'not > asserted'. Keir? Yes, this is correct. Possibly the naming of v[ioa]pic_irq_positive_edge is unfortunate! Really it is indicating an asserting edge, regardless of whether that edge is driving to a high or low voltage. -- Keir >> Which sadly makes me feel even more >> nervous about your change here. Plus if IRQ8 is active low in our >> emulation, then the if and else bodies would need to be switched >> (which then wouldn't work because of deassert_irq() being too >> simplistic). > > OK, so should I just respin without patch 1/4 and pretend I never saw > any of this mess? :) > > Tim.