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[209.51.188.17]) by mx.google.com with ESMTPS id a13si30990931ybr.197.2021.07.23.10.09.39 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 23 Jul 2021 10:09:39 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=fail header.i=@linaro.org header.s=google header.b=XzsI0PTP; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1]:51730 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m6yg6-00039f-Uf for patch@linaro.org; Fri, 23 Jul 2021 13:09:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58192) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m6ybB-0000D8-Bu for qemu-devel@nongnu.org; Fri, 23 Jul 2021 13:04:34 -0400 Received: from mail-wr1-x430.google.com ([2a00:1450:4864:20::430]:37565) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1m6yb9-0005X8-Mg for qemu-devel@nongnu.org; Fri, 23 Jul 2021 13:04:33 -0400 Received: by mail-wr1-x430.google.com with SMTP id l4so3095696wrs.4 for ; Fri, 23 Jul 2021 10:04:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=PPI621meN9sJrxAgzk9pLnBrmGAkbqEosNwrArAkihY=; b=XzsI0PTPeIomitRVvlXgaIQdK5OlW/gQyFQ9NEsMjcOlHwLwgbWWrDh1Ag4KvD5Lv6 yp0uFhXxDr8+hLq3J/V8Wnwf/IT6v4qErZrs7JARw3bc6Il88kW/fuNW1lE9GecMMo6h jRuUKGtMJysC1enN7z92n1qAZYbR3DvCavmz388SDS9FaWtYUAoKNTz1YBEg6LPOhDtB GRfTWAXdTTb1mwjluIxwxC6AZnQG+/0NHg0QzfpQjaow+FlWQD0LDvmtyVSt1pb5cheB hQzp6VTvcqDk3RSNLuollfSQWzJdkA8zGD+AXMKPyTZW07rLw6pngwC/n67RUxMJSh9M iXRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PPI621meN9sJrxAgzk9pLnBrmGAkbqEosNwrArAkihY=; b=bJoKznSTMOqhYqZN90yH2e7S4kiZVOZTjQZntchLDx2oAtPjuntALFwWa6EmrRwvN9 4T/Devs6ysQb0fkSZJAse0bmNJD8uY9DoDYO2/Hu9Numc11h4iZZGvNd5jFyExXASUhc +UMFwj4IjUQCzy1adp3UY0HH/BWgMGwzjHGkhLtvJYpsiRSG3GlNIkYdGe4Ms31sLRBw 4fq1+y7jhDHnQABSha+5G8NSPjydSFWeseB4KijtVTs7MJHE0+dSPcVszMQuhNVGfeZp GHr2k7bbcrD8Ec9cfnXseaQ6kmqnkFS1d2XZe3rOWj9P0JEt5SdAcUK4QUPO+uO7mtng WraQ== X-Gm-Message-State: AOAM530ZAYvRebQG8dK29lEEPyM2a0TyIZAqTDtbUVwv9bwJDdWUlHdi RzV/F3wQNXJJiyyLiqdBiMq30g== X-Received: by 2002:a05:6000:1248:: with SMTP id j8mr6299018wrx.391.1627059869096; Fri, 23 Jul 2021 10:04:29 -0700 (PDT) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id n5sm32285145wri.31.2021.07.23.10.03.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Jul 2021 10:04:00 -0700 (PDT) Received: from zen.lan (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 75EA21FF8C; Fri, 23 Jul 2021 18:03:54 +0100 (BST) From: =?utf-8?q?Alex_Benn=C3=A9e?= To: peter.maydell@linaro.org Subject: [PULL 02/28] docs: collect the disparate device emulation docs into one section Date: Fri, 23 Jul 2021 18:03:28 +0100 Message-Id: <20210723170354.18975-3-alex.bennee@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210723170354.18975-1-alex.bennee@linaro.org> References: <20210723170354.18975-1-alex.bennee@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::430; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x430.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=ham 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: =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , Eduardo Habkost , qemu-devel@nongnu.org, Markus Armbruster , Paolo Bonzini , =?utf-8?q?Alex_Benn=C3=A9e?= Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" While we are at it add a brief preamble that explains some of the common concepts in QEMU's device emulation which will hopefully lead to less confusing about our dizzying command line options. Signed-off-by: Alex Bennée Reviewed-by: Markus Armbruster Cc: Paolo Bonzini Cc: Daniel P. Berrangé Cc: Eduardo Habkost Message-Id: <20210720232703.10650-3-alex.bennee@linaro.org> -- 2.20.1 diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst new file mode 100644 index 0000000000..8adf05f606 --- /dev/null +++ b/docs/system/device-emulation.rst @@ -0,0 +1,89 @@ +.. _device-emulation: + +Device Emulation +---------------- + +QEMU supports the emulation of a large number of devices from +peripherals such network cards and USB devices to integrated systems +on a chip (SoCs). Configuration of these is often a source of +confusion so it helps to have an understanding of some of the terms +used to describes devices within QEMU. + +Common Terms +~~~~~~~~~~~~ + +Device Front End +================ + +A device front end is how a device is presented to the guest. The type +of device presented should match the hardware that the guest operating +system is expecting to see. All devices can be specified with the +``--device`` command line option. Running QEMU with the command line +options ``--device help`` will list all devices it is aware of. Using +the command line ``--device foo,help`` will list the additional +configuration options available for that device. + +A front end is often paired with a back end, which describes how the +host's resources are used in the emulation. + +Device Buses +============ + +Most devices will exist on a BUS of some sort. Depending on the +machine model you choose (``-M foo``) a number of buses will have been +automatically created. In most cases the BUS a device is attached to +can be inferred, for example PCI devices are generally automatically +allocated to the next free address of first PCI bus found. However in +complicated configurations you can explicitly specify what bus +(``bus=ID``) a device is attached to along with its address +(``addr=N``). + +Some devices, for example a PCI SCSI host controller, will add an +additional buses to the system that other devices can be attached to. +A hypothetical chain of devices might look like: + + --device foo,bus=pci.0,addr=0,id=foo + --device bar,bus=foo.0,addr=1,id=baz + +which would be a bar device (with the ID of baz) which is attached to +the first foo bus (foo.0) at address 1. The foo device which provides +that bus is itself is attached to the first PCI bus (pci.0). + + +Device Back End +=============== + +The back end describes how the data from the emulated device will be +processed by QEMU. The configuration of the back end is usually +specific to the class of device being emulated. For example serial +devices will be backed by a ``--chardev`` which can redirect the data +to a file or socket or some other system. Storage devices are handled +by ``--blockdev`` which will specify how blocks are handled, for +example being stored in a qcow2 file or accessing a raw host disk +partition. Back ends can sometimes be stacked to implement features +like snapshots. + +While the choice of back end is generally transparent to the guest, +there are cases where features will not be reported to the guest if +the back end is unable to support it. + +Device Pass Through +=================== + +Device pass through is where the device is actually given access to +the underlying hardware. This can be as simple as exposing a single +USB device on the host system to the guest or dedicating a video card +in a PCI slot to the exclusive use of the guest. + + +Emulated Devices +~~~~~~~~~~~~~~~~ + +.. toctree:: + :maxdepth: 1 + + devices/ivshmem.rst + devices/net.rst + devices/nvme.rst + devices/usb.rst + devices/virtio-pmem.rst diff --git a/docs/system/ivshmem.rst b/docs/system/devices/ivshmem.rst similarity index 100% rename from docs/system/ivshmem.rst rename to docs/system/devices/ivshmem.rst diff --git a/docs/system/net.rst b/docs/system/devices/net.rst similarity index 100% rename from docs/system/net.rst rename to docs/system/devices/net.rst diff --git a/docs/system/nvme.rst b/docs/system/devices/nvme.rst similarity index 100% rename from docs/system/nvme.rst rename to docs/system/devices/nvme.rst diff --git a/docs/system/usb.rst b/docs/system/devices/usb.rst similarity index 100% rename from docs/system/usb.rst rename to docs/system/devices/usb.rst diff --git a/docs/system/virtio-pmem.rst b/docs/system/devices/virtio-pmem.rst similarity index 100% rename from docs/system/virtio-pmem.rst rename to docs/system/devices/virtio-pmem.rst diff --git a/docs/system/index.rst b/docs/system/index.rst index fda4b1b705..64a424ae99 100644 --- a/docs/system/index.rst +++ b/docs/system/index.rst @@ -11,15 +11,12 @@ or Hypervisor.Framework. quickstart invocation + device-emulation keys mux-chardev monitor images - net virtio-net-failover - usb - nvme - ivshmem linuxboot generic-loader guest-loader @@ -30,7 +27,6 @@ or Hypervisor.Framework. gdb managed-startup cpu-hotplug - virtio-pmem pr-manager targets security