From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ACAFEC07E96 for ; Thu, 15 Jul 2021 06:12:02 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0C53961358 for ; Thu, 15 Jul 2021 06:12:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C53961358 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50046 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m3ubI-000871-V4 for qemu-devel@archiver.kernel.org; Thu, 15 Jul 2021 02:12:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53350) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m3uaS-0007PI-6y for qemu-devel@nongnu.org; Thu, 15 Jul 2021 02:11:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:53581) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m3uaL-0006Vx-KI for qemu-devel@nongnu.org; Thu, 15 Jul 2021 02:11:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626329459; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XToVkY4mKnxfmsFVxdNU9x8RCbeSXBFzMYoDDiYZ2us=; b=PsYbub9eVvWtD9Bk/jOK91nwfU3YBapTvp4+HUvMiiqGFKGL+2MfFOJzr7v5FCYRZVfk1y b3l0kk2YR7oj2IVvUMqfp7k3RoahsCFmOLsinzygcxcGMOwkpJWEspiKYuZbScJWh3qxU3 d8KKlZd1g1UsOW1AhBfUyBdGUAPnTKc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-376-Db5N7AScOdaqS-cDIdWb8Q-1; Thu, 15 Jul 2021 02:10:57 -0400 X-MC-Unique: Db5N7AScOdaqS-cDIdWb8Q-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AB57A10C1ADC; Thu, 15 Jul 2021 06:10:56 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-81.ams2.redhat.com [10.36.112.81]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 39FDB60583; Thu, 15 Jul 2021 06:10:56 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id C59F9113865F; Thu, 15 Jul 2021 08:10:54 +0200 (CEST) From: Markus Armbruster To: Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH v2 02/21] docs: collect the disparate device emulation docs into one section References: <20210714182056.25888-1-alex.bennee@linaro.org> <20210714182056.25888-3-alex.bennee@linaro.org> Date: Thu, 15 Jul 2021 08:10:54 +0200 In-Reply-To: <20210714182056.25888-3-alex.bennee@linaro.org> ("Alex =?utf-8?Q?Benn=C3=A9e=22's?= message of "Wed, 14 Jul 2021 19:20:37 +0100") Message-ID: <8735sgds41.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: Paolo Bonzini , =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Cc: QOM maintainers for additional eyes. Alex Benn=C3=A9e writes: > 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 Benn=C3=A9e > Message-Id: <20210714093638.21077-3-alex.bennee@linaro.org> > --- > docs/system/device-emulation.rst | 78 +++++++++++++++++++++++ > docs/system/{ =3D> devices}/ivshmem.rst | 0 > docs/system/{ =3D> devices}/net.rst | 0 > docs/system/{ =3D> devices}/nvme.rst | 0 > docs/system/{ =3D> devices}/usb.rst | 0 > docs/system/{ =3D> devices}/virtio-pmem.rst | 0 > docs/system/index.rst | 6 +- > 7 files changed, 79 insertions(+), 5 deletions(-) > create mode 100644 docs/system/device-emulation.rst > rename docs/system/{ =3D> devices}/ivshmem.rst (100%) > rename docs/system/{ =3D> devices}/net.rst (100%) > rename docs/system/{ =3D> devices}/nvme.rst (100%) > rename docs/system/{ =3D> devices}/usb.rst (100%) > rename docs/system/{ =3D> devices}/virtio-pmem.rst (100%) > > diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulat= ion.rst > new file mode 100644 > index 0000000000..3156eeac2d > --- /dev/null > +++ b/docs/system/device-emulation.rst > @@ -0,0 +1,78 @@ > +.. _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 > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > + > +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 > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > + > +All devices exist on a BUS. Depending on the machine model you choose This isn't true anymore; there are bus-less devices. To show the user-pluggable ones, try $ qemu-system-FOO -device help | grep -v '", bus' > +(``-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 slot of the PCI bus. However in complicated configurations you "The PCI bus" tacitly assumes there's just one. We actually pick the first bus (in qtree pre-order) that can take another device. Best not to rely on the search order; if you care which bus to plug into, specify it with bus=3DID. "Next free slot" is about the device address on the bus. Should we explain the concept "device address on a bus"? > +can explicitly specify what bus a device is attached to and its > +address. Some devices, for example a PCI SCSI host controller, will > +add an additional bus to the system that other devices can be attached A device can add more than one bus. > +to. > + > +Device Back End > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > + > +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 Comma, I think. > +there are cases where features will not be reported to the guest if > +the back end is unable to support it. > + > +Device Pass Through > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > + > +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. Thanks for writing this up! > + > + > +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-pme= m.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 6092eb2d91..641d243ba4 100644 > --- a/docs/system/index.rst > +++ b/docs/system/index.rst > @@ -16,15 +16,12 @@ Contents: > =20 > quickstart > invocation > + device-emulation > keys > mux-chardev > monitor > images > - net > virtio-net-failover > - usb > - nvme > - ivshmem > linuxboot > generic-loader > guest-loader > @@ -35,7 +32,6 @@ Contents: > gdb > managed-startup > cpu-hotplug > - virtio-pmem > pr-manager > targets > security