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[82.27.106.168]) by smtp.gmail.com with ESMTPSA id o23sm140288wms.18.2021.10.11.10.34.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Oct 2021 10:34:56 -0700 (PDT) Date: Mon, 11 Oct 2021 18:34:35 +0100 From: Jean-Philippe Brucker To: Haiwei Li Subject: Re: [PATCH v4 00/11] virtio-iommu: Add ACPI support Message-ID: References: <20211001173358.863017-1-jean-philippe@linaro.org> <20211005113719-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=2a00:1450:4864:20::434; envelope-from=jean-philippe@linaro.org; helo=mail-wr1-x434.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, ehabkost@redhat.com, "Michael S. Tsirkin" , richard.henderson@linaro.org, qemu-devel@nongnu.org, shannon.zhaosl@gmail.com, qemu-arm@nongnu.org, eric.auger@redhat.com, Paolo Bonzini , ani@anisinha.ca, imammedo@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Haiwei, On Mon, Oct 11, 2021 at 06:10:07PM +0800, Haiwei Li wrote: [...] > Gave up waiting for root file system device. Common problems: > - Boot args (cat /proc/cmdline) > - Check rootdelay= (did the system wait long enough?) > - Missing modules (cat /proc/modules; ls /dev) > ALERT! UUID=3caf26b5-4d08-43e0-8634-7573269c4f70 does not exist. > Dropping to a shell! > > Any suggestions? Thanks. It's possible that the rootfs is on a disk behind the IOMMU, and the IOMMU driver doesn't get loaded. That could happen, for example, if the virtio-iommu module is not present in the initramfs. Since IOMMU drivers are typically built into the kernel rather than modules, distro tools that build the initramfs might not pick up IOMMU modules. I'm guessing this could be the issue here because of the hints and "Dropping to a shell" line. The clean solution will be to patch the initramfs tools to learn about IOMMU drivers (I'm somewhat working on that). In the meantime, if this is indeed the problem, you could try explicitly adding the virtio-iommu module to the initramfs, or building the kernel with CONFIG_VIRTIO_IOMMU=y rather than =m, though that requires VIRTIO and VIRTIO_PCI to be built-in as well. Thanks, Jean