Signed-off-by: Pierrick Bouvier <pierrick.bouv...@linaro.org> --- docs/devel/control-flow-integrity.rst | 2 + docs/devel/multi-thread-tcg.rst | 2 + docs/glossary/index.rst | 238 ++++++++++++++++++++++++++ docs/index.rst | 1 + docs/system/arm/virt.rst | 2 + docs/system/images.rst | 2 + docs/tools/qemu-nbd.rst | 2 + 7 files changed, 249 insertions(+) create mode 100644 docs/glossary/index.rst
diff --git a/docs/devel/control-flow-integrity.rst b/docs/devel/control-flow-integrity.rst index e6b73a4fe1a..3d5702fa4cc 100644 --- a/docs/devel/control-flow-integrity.rst +++ b/docs/devel/control-flow-integrity.rst @@ -1,3 +1,5 @@ +.. _cfi: + ============================ Control-Flow Integrity (CFI) ============================ diff --git a/docs/devel/multi-thread-tcg.rst b/docs/devel/multi-thread-tcg.rst index d706c27ea74..7fd0a07633d 100644 --- a/docs/devel/multi-thread-tcg.rst +++ b/docs/devel/multi-thread-tcg.rst @@ -4,6 +4,8 @@ This work is licensed under the terms of the GNU GPL, version 2 or later. See the COPYING file in the top-level directory. +.. _mttcg: + ================== Multi-threaded TCG ================== diff --git a/docs/glossary/index.rst b/docs/glossary/index.rst new file mode 100644 index 00000000000..a2d4f3eae16 --- /dev/null +++ b/docs/glossary/index.rst @@ -0,0 +1,238 @@ +.. _Glossary: + +-------- +Glossary +-------- + +This section of the manual presents *simply* acronyms and terms QEMU developers +use. + +Accelerator +----------- + +A specific API used to accelerate execution of guest instructions. It can be +hardware-based, through a virtualization API provided by the host OS (kvm, hvf, +whpx, ...) or software-based (tcg). See this description of `supported +accelerators<Accelerators>`. + +Board +----- + +QEMU system defines board models for various architectures. It's a description +of a SoC (system-on-chip) with various devices pre-configured, and can be +selected with the option ``-machine`` of qemu-system. +For virtual machines, you'll use ``virt`` board model, designed for this use +case. As an example, for Arm architecture, you can find the `model code +<https://gitlab.com/qemu-project/qemu/-/blob/master/hw/arm/virt.c>`_ and +associated `documentation <arm-virt>`. + +Block +----- + +Block drivers are the available `disk formats <block-drivers>` available, and +block devices `(see Block device section on options page)<sec_005finvocation>` +are using them to implement disks for a virtual machine. + +CFI +--- + +Control Flow Integrity is a hardening technique used to prevent exploits +targeting QEMU by detecting unexpected branches during execution. QEMU `actively +supports<cfi>` being compiled with CFI enabled. + +Device +------ + +QEMU is able to emulate a CPU, and all the hardware interacting with it, +including many devices. When QEMU runs a virtual machine using a hardware-based +accelerator, it is responsible for emulating, using software, all devices. + +EDK2 +---- + +EDK2, as known as `TianoCore <https://www.tianocore.org/>`_, is an open source +implementation of UEFI standard. It's ran by QEMU to support UEFI for virtual +machines. + +gdbstub +------- + +QEMU implements a `gdb server <GDB usage>`, allowing gdb to attach to it and +debug a running virtual machine, or a program in user-mode. This allows to debug +a given architecture without having access to hardware. + +glib2 +----- + +`GLib2 <https://docs.gtk.org/glib/>`_ is one of the most important library we +are using through the codebase. It provides many data structures, macros, string +and thread utilities and portable functions across different OS. It's required +to build QEMU. + +Guest agent +----------- + +`QEMU Guest agent <qemu-ga>` is a daemon intended to be executed by guest +virtual machines and providing various services to help QEMU to interact with +it. + +Guest/Host +---------- + +Guest is the architecture of the virtual machine, which is emulated. +Host is the architecture on which QEMU is running on, which is native. + +Hypervisor +---------- + +The formal definition of an hypervisor is a program than can be used to manage a +virtual machine. QEMU itself is an hypervisor. + +In the context of QEMU, an hypervisor is an API, provided by the Host OS, +allowing to execute virtual machines. Linux implementation is KVM (and supports +Xen as well). For MacOS, it's HVF. Windows defines WHPX. And NetBSD provides +NVMM. + +Migration +--------- + +QEMU can save and restore the execution of a virtual machine, including across +different machines. This is provided by the `Migration framework<migration>`. + +NBD +--- + +`QEMU Network Block Device server <qemu-nbd>` is a tool that can be used to +mount and access QEMU images, providing functionality similar to a loop device. + +Mailing List +------------ + +This is `where <https://wiki.qemu.org/Contribute/MailingLists>`_ all the +development happens! Changes are posted as series, that all developers can +review and share feedback for. + +For reporting issues, our `GitLab +<https://gitlab.com/qemu-project/qemu/-/issues>`_ tracker is the best place. + +MMU / softmmu +------------- + +The Memory Management Unit is responsible for translating virtual addresses to +physical addresses and managing memory protection. QEMU system mode is named +"softmmu" precisely because it implements this in software, including a TLB +(Translation lookaside buffer), for the guest virtual machine. + +QEMU user-mode does not implement a full software MMU, but "simply" translates +virtual addresses by adding a specific offset, and relying on host MMU/OS +instead. + +Monitor / QMP / HMP +------------------- + +`QEMU Monitor <QEMU monitor>` is a text interface which can be used to interact +with a running virtual machine. + +QMP stands for QEMU Monitor Protocol and is a json based interface. +HMP stands for Human Monitor Protocol and is a set of text commands available +for users who prefer natural language to json. + +MTTCG +----- + +Multiple cpus support was first implemented using a round-robin algorithm +running on a single thread. Later on, `Multi-threaded TCG <mttcg>` was developed +to benefit from multiple cores to speed up execution. + +Plugins +------- + +`TCG Plugins <TCG Plugins>` is an API used to instrument guest code, in system +and user mode. The end goal is to have a similar set of functionality compared +to `DynamoRIO <https://dynamorio.org/>`_ or `valgrind <https://valgrind.org/>`_. + +One key advantage of QEMU plugins is that they can be used to perform +architecture agnostic instrumentation. + +Patchwork +--------- + +`Patchwork <https://patchew.org/QEMU/>`_ is a website that tracks +patches on the Mailing List. + +PR +-- + +Once a series is reviewed and accepted by a subsystem maintainer, it will be +included in a PR (Pull Request) that the project maintainer will merge into QEMU +main branch, after running tests. + +QCOW +---- + +QEMU Copy On Write is a disk format developed by QEMU. It provides transparent +compression, automatic extension, and many other advantages over a raw image. + +QEMU +---- + +`QEMU (Quick Emulator) <https://www.qemu.org/>`_ is a generic and open source +machine emulator and virtualizer. + +QOM +--- + +`QEMU Object Model <qom>` is an object oriented API used to define various +devices and hardware in the QEMU codebase. + +Record/replay +------------- + +`Record/replay <replay>` is a feature of QEMU allowing to have a deterministic +and reproducible execution of a virtual machine. + +Rust +---- + +`A new programming language <https://www.rust-lang.org/>`_, memory safe by +default. We didn't see a more efficient way to create debates and tensions in +a community of C programmers since the birth of C++. + +System mode +----------- + +QEMU System mode emulates a full machine, including its cpu, memory and devices. +It can be accelerated to hardware speed by using one of the hypervisors QEMU +supports. It is referenced as softmmu as well. + +TCG +--- + +`Tiny Code Generator <tcg>` is an intermediate representation (IR) used to run +guest instructions on host cpu, with both architectures possibly being +different. + +It is one of the accelerator supported by QEMU, and supports a lot of +guest/host architectures. + +User mode +--------- + +QEMU User mode allows to run programs for a guest architecture, on a host +architecture, by translating system calls and using TCG. It is available for +Linux and BSD. + +VirtIO +------ + +VirtIO is an open standard used to define and implement virtual devices with a +minimal overhead, defining a set of data structures and hypercalls (similar to +system calls, but targeting an hypervisor, which happens to be QEMU in our +case). It's designed to be more efficient than emulating a real device, by +minimizing the amount of interactions between a guest VM and its hypervisor. + +vhost-user +---------- + +`Vhost-user <vhost_user>` is an interface used to implement VirtIO devices +outside of QEMU itself. diff --git a/docs/index.rst b/docs/index.rst index cb5e5098b65..2cad84cd77c 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -21,3 +21,4 @@ Welcome to QEMU's documentation! specs/index devel/index codebase/index + glossary/index diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst index e67e7f0f7c5..11ceb898264 100644 --- a/docs/system/arm/virt.rst +++ b/docs/system/arm/virt.rst @@ -1,3 +1,5 @@ +.. _arm-virt: + 'virt' generic virtual platform (``virt``) ========================================== diff --git a/docs/system/images.rst b/docs/system/images.rst index d000bd6b6f1..a5551173c97 100644 --- a/docs/system/images.rst +++ b/docs/system/images.rst @@ -82,4 +82,6 @@ VM snapshots currently have the following known limitations: - A few device drivers still have incomplete snapshot support so their state is not saved or restored properly (in particular USB). +.. _block-drivers: + .. include:: qemu-block-drivers.rst.inc diff --git a/docs/tools/qemu-nbd.rst b/docs/tools/qemu-nbd.rst index 329f44d9895..4f21b7904ac 100644 --- a/docs/tools/qemu-nbd.rst +++ b/docs/tools/qemu-nbd.rst @@ -1,3 +1,5 @@ +.. _qemu-nbd: + ===================================== QEMU Disk Network Block Device Server ===================================== -- 2.39.5
