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[209.51.188.17]) by mx.google.com with ESMTPS id s192si7982892ywg.112.2019.04.02.08.56.33 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 02 Apr 2019 08:56:34 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([127.0.0.1]:41929 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hBLm5-0000DG-FP for alex.bennee@linaro.org; Tue, 02 Apr 2019 11:56:33 -0400 Received: from eggs.gnu.org ([209.51.188.92]:55220) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hBLlq-0000Bh-Eq for qemu-arm@nongnu.org; Tue, 02 Apr 2019 11:56:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hBLlo-0006dL-Qj for qemu-arm@nongnu.org; Tue, 02 Apr 2019 11:56:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53618) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hBLlo-0006T1-GS; Tue, 02 Apr 2019 11:56:16 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E51383092644; Tue, 2 Apr 2019 15:56:10 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-120-182.rdu2.redhat.com [10.10.120.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 596F97D14E; Tue, 2 Apr 2019 15:56:01 +0000 (UTC) From: Laszlo Ersek To: Auger Eric , Igor Mammedov References: <20190321104745.28068-1-shameerali.kolothum.thodi@huawei.com> <20190321104745.28068-8-shameerali.kolothum.thodi@huawei.com> <98c7f0fd-8446-8897-0808-e7615af29670@redhat.com> <5FC3163CFD30C246ABAA99954A238FA83933836A@lhreml524-mbs.china.huawei.com> <0dcd3f3c-15c4-318f-28bd-4b6706708c0d@redhat.com> <459862f9-18f7-0a37-dfb9-b8ca9aa6a2d2@redhat.com> <20190402094257.218aa0e5@redhat.com> <9b776e3b-7b1b-239d-bc36-6bbd78f8b67e@redhat.com> <91a906c2-ef90-3aec-2b2c-fbb63c41f7c2@redhat.com> Message-ID: <59dfd9cd-3762-cbb6-0823-e1247ec5fcd7@redhat.com> Date: Tue, 2 Apr 2019 17:56:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <91a906c2-ef90-3aec-2b2c-fbb63c41f7c2@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 02 Apr 2019 15:56:11 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH v3 07/10] hw/arm/virt: Introduce opt-in feature "fdt" X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "peter.maydell@linaro.org" , "sameo@linux.intel.com" , Ard Biesheuvel , "qemu-devel@nongnu.org" , Shameerali Kolothum Thodi , Linuxarm , "shannon.zhaosl@gmail.com" , "qemu-arm@nongnu.org" , "xuwei \(O\)" , "sebastien.boeuf@intel.com" , Leif Lindholm Errors-To: qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-arm" X-TUID: kemWaSONX29w On 04/02/19 17:52, Laszlo Ersek wrote: > On 04/02/19 17:42, Auger Eric wrote: >>>>> The firmware does consume DT: >>>>> >>>>> - If you start QEMU *with* "-no-acpi", then the DT is both consumed by >>>>> the firmware (for its own information needs), and passed on to the OS. >>>>> >>>>> - If you start QEMU *without* "-no-acpi" (the default), then the DT is >>>>> consumed only by the firmware (for its own information needs), and the >>>>> DT is hidden from the OS. The OS gets only the ACPI content >>>>> (processed/prepared as described above). > >> I am confused by the above statement actually. In the above case what >> does happen if you pass the acpi=off in the kernel boot parameters? > > If you launch QEMU with "-no-acpi" and you pass "acpi=off" to the guest > kernel, then the kernel will not boot successfully, as it will not get > DT from the firmware, and it will ignore the ACPI tables that it does > get from the firmware. Sorry, I ended up answering "what happens when you run QEMU *without* -no-acpi and pass acpi=off to the guest kernel". To explain what happens when you boot *with* -no-acpi: in that case, "acpi=off" doesn't matter, since the guest kernel doesn't get ACPI tables anyway. The kernel will go for DT. Thanks Laszlo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:55241) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hBLlt-0000Dt-Ih for qemu-devel@nongnu.org; Tue, 02 Apr 2019 11:56:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hBLlr-0006n0-HZ for qemu-devel@nongnu.org; Tue, 02 Apr 2019 11:56:21 -0400 From: Laszlo Ersek References: <20190321104745.28068-1-shameerali.kolothum.thodi@huawei.com> <20190321104745.28068-8-shameerali.kolothum.thodi@huawei.com> <98c7f0fd-8446-8897-0808-e7615af29670@redhat.com> <5FC3163CFD30C246ABAA99954A238FA83933836A@lhreml524-mbs.china.huawei.com> <0dcd3f3c-15c4-318f-28bd-4b6706708c0d@redhat.com> <459862f9-18f7-0a37-dfb9-b8ca9aa6a2d2@redhat.com> <20190402094257.218aa0e5@redhat.com> <9b776e3b-7b1b-239d-bc36-6bbd78f8b67e@redhat.com> <91a906c2-ef90-3aec-2b2c-fbb63c41f7c2@redhat.com> Message-ID: <59dfd9cd-3762-cbb6-0823-e1247ec5fcd7@redhat.com> Date: Tue, 2 Apr 2019 17:56:00 +0200 MIME-Version: 1.0 In-Reply-To: <91a906c2-ef90-3aec-2b2c-fbb63c41f7c2@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 07/10] hw/arm/virt: Introduce opt-in feature "fdt" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Auger Eric , Igor Mammedov Cc: Ard Biesheuvel , "peter.maydell@linaro.org" , "sameo@linux.intel.com" , "qemu-devel@nongnu.org" , Shameerali Kolothum Thodi , Linuxarm , "shannon.zhaosl@gmail.com" , "qemu-arm@nongnu.org" , "xuwei (O)" , "sebastien.boeuf@intel.com" , Leif Lindholm On 04/02/19 17:52, Laszlo Ersek wrote: > On 04/02/19 17:42, Auger Eric wrote: >>>>> The firmware does consume DT: >>>>> >>>>> - If you start QEMU *with* "-no-acpi", then the DT is both consumed by >>>>> the firmware (for its own information needs), and passed on to the OS. >>>>> >>>>> - If you start QEMU *without* "-no-acpi" (the default), then the DT is >>>>> consumed only by the firmware (for its own information needs), and the >>>>> DT is hidden from the OS. The OS gets only the ACPI content >>>>> (processed/prepared as described above). > >> I am confused by the above statement actually. In the above case what >> does happen if you pass the acpi=off in the kernel boot parameters? > > If you launch QEMU with "-no-acpi" and you pass "acpi=off" to the guest > kernel, then the kernel will not boot successfully, as it will not get > DT from the firmware, and it will ignore the ACPI tables that it does > get from the firmware. Sorry, I ended up answering "what happens when you run QEMU *without* -no-acpi and pass acpi=off to the guest kernel". To explain what happens when you boot *with* -no-acpi: in that case, "acpi=off" doesn't matter, since the guest kernel doesn't get ACPI tables anyway. The kernel will go for DT. Thanks Laszlo