From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33757) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3mrw-0007NG-GV for qemu-devel@nongnu.org; Tue, 01 Dec 2015 10:29:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a3mrv-0006Vn-Im for qemu-devel@nongnu.org; Tue, 01 Dec 2015 10:29:28 -0500 References: <1447680189-2128-1-git-send-email-shannon.zhao@linaro.org> <1447680189-2128-2-git-send-email-shannon.zhao@linaro.org> <20151201142146.2bcda69f@nial.brq.redhat.com> <01d201d12c47$5a77dd00$0f679700$@samsung.com> From: Wei Huang Message-ID: <565DBCCF.7050404@redhat.com> Date: Tue, 1 Dec 2015 09:29:19 -0600 MIME-Version: 1.0 In-Reply-To: <01d201d12c47$5a77dd00$0f679700$@samsung.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 1/8] hw/arm/virt: Add a GPIO controller List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pavel Fedin , 'Peter Maydell' , 'Igor Mammedov' Cc: 'G Gregory' , "'Michael S. Tsirkin'" , "'Huangpeng (Peter)'" , 'QEMU Developers' , 'qemu-arm' , 'Shannon Zhao' , 'Shannon Zhao' On 12/01/2015 08:48 AM, Pavel Fedin wrote: > Hello! > >>>> ACPI 5.0 supports GPIO-signaled ACPI Events. This can be used for >>>> powerdown, hotplug evnets. Add a GPIO controller in machine virt, >>> s/evnets/events/ >>> >>>> to support powerdown, maybe can be used for cpu hotplug. And >>>> here we use pl061. > > Sorry for late jumping in, but this was the first message Cc'ed to me. > With these devices virt machine IMHO goes farther and farther away from its initial goal: be a minimalistic virtual box, which ensures maximum possible compatibility and portability. > virt machine already supports poweroff using PSCI interface. Why we need to add more hardware? Can't ACPI deal with PSCI? PSCI handles the actions initiated from the inside of OS. Examples include system shutdown and hotplug (still inside OS). From this perspective PSCI works well. However this communication is one-direction: there isn't a way to communicate from the outside (e.g. libvirt) to the guest OS. For instance, "system_powerdown" qmp command won't work because guest OS can't receive the notification. > To tell the truth, i dislike ACPI + EFI thing at all. It looks like cramming PC-oriented firmware into architecture for which it was never meant to be written. Too much overcomplications, we drop already established things and reinvent a (triangular) wheel, but what's the purpose? Is it being done only because vendors want obscure proprietary firmware instead of old good u-boot? > > Kind regards, > Pavel Fedin > Expert Engineer > Samsung Electronics Research center Russia >