1======== 2Codebase 3======== 4 5This section presents the various parts of QEMU and how the codebase is 6organized. 7 8Beyond giving succinct descriptions, the goal is to offer links to various 9parts of the documentation/codebase. 10 11Subsystems 12---------- 13 14An exhaustive list of subsystems and associated files can be found in the 15`MAINTAINERS <https://gitlab.com/qemu-project/qemu/-/blob/master/MAINTAINERS>`_ 16file. 17 18Some of the main QEMU subsystems are: 19 20- `Accelerators<Accelerators>` 21- Block devices and `disk images<disk images>` support 22- `CI<ci>` and `Tests<testing>` 23- `Devices<device-emulation>` & Board models 24- `Documentation <documentation-root>` 25- `GDB support<GDB usage>` 26- :ref:`Migration<migration>` 27- `Monitor<QEMU monitor>` 28- :ref:`QOM (QEMU Object Model)<qom>` 29- `System mode<System emulation>` 30- :ref:`TCG (Tiny Code Generator)<tcg>` 31- `User mode<user-mode>` (`Linux<linux-user-mode>` & `BSD<bsd-user-mode>`) 32- User Interfaces 33 34More documentation on QEMU subsystems can be found on :ref:`internal-subsystem` 35page. 36 37The Grand tour 38-------------- 39 40We present briefly here what every folder in the top directory of the codebase 41contains. Hop on! 42 43The folder name links here will take you to that folder in our gitlab 44repository. Other links will take you to more detailed documentation for that 45subsystem, where we have it. Unfortunately not every subsystem has documentation 46yet, so sometimes the source code is all you have. 47 48* `accel <https://gitlab.com/qemu-project/qemu/-/tree/master/accel>`_: 49 Infrastructure and architecture agnostic code related to the various 50 `accelerators <Accelerators>` supported by QEMU 51 (TCG, KVM, hvf, whpx, xen, nvmm). 52 Contains interfaces for operations that will be implemented per 53 `target <https://gitlab.com/qemu-project/qemu/-/tree/master/target>`_. 54* `audio <https://gitlab.com/qemu-project/qemu/-/tree/master/audio>`_: 55 Audio (host) support. 56* `authz <https://gitlab.com/qemu-project/qemu/-/tree/master/authz>`_: 57 `QEMU Authorization framework<client authorization>`. 58* `backends <https://gitlab.com/qemu-project/qemu/-/tree/master/backends>`_: 59 Various backends that are used to access resources on the host (e.g. for 60 random number generation, memory backing or cryptographic functions). 61* `block <https://gitlab.com/qemu-project/qemu/-/tree/master/block>`_: 62 Block devices and `image formats<disk images>` implementation. 63* `bsd-user <https://gitlab.com/qemu-project/qemu/-/tree/master/bsd-user>`_: 64 `BSD User mode<bsd-user-mode>`. 65* build: Where the code built goes by default. You can tell the QEMU build 66 system to put the built code anywhere else you like. 67* `chardev <https://gitlab.com/qemu-project/qemu/-/tree/master/chardev>`_: 68 Various backends used by char devices. 69* `common-user <https://gitlab.com/qemu-project/qemu/-/tree/master/common-user>`_: 70 User-mode assembly code for dealing with signals occurring during syscalls. 71* `configs <https://gitlab.com/qemu-project/qemu/-/tree/master/configs>`_: 72 Makefiles defining configurations to build QEMU. 73* `contrib <https://gitlab.com/qemu-project/qemu/-/tree/master/contrib>`_: 74 Community contributed devices/plugins/tools. 75* `crypto <https://gitlab.com/qemu-project/qemu/-/tree/master/crypto>`_: 76 Cryptographic algorithms used in QEMU. 77* `disas <https://gitlab.com/qemu-project/qemu/-/tree/master/disas>`_: 78 Disassembly functions used by QEMU target code. 79* `docs <https://gitlab.com/qemu-project/qemu/-/tree/master/docs>`_: 80 QEMU Documentation. 81* `dump <https://gitlab.com/qemu-project/qemu/-/tree/master/dump>`_: 82 Code to dump memory of a running VM. 83* `ebpf <https://gitlab.com/qemu-project/qemu/-/tree/master/ebpf>`_: 84 eBPF program support in QEMU. `virtio-net RSS<ebpf-rss>` uses it. 85* `fpu <https://gitlab.com/qemu-project/qemu/-/tree/master/fpu>`_: 86 Floating-point software emulation. 87* `fsdev <https://gitlab.com/qemu-project/qemu/-/tree/master/fsdev>`_: 88 `VirtFS <https://www.linux-kvm.org/page/VirtFS>`_ support. 89* `gdbstub <https://gitlab.com/qemu-project/qemu/-/tree/master/gdbstub>`_: 90 `GDB <GDB usage>` support. 91* `gdb-xml <https://gitlab.com/qemu-project/qemu/-/tree/master/gdb-xml>`_: 92 Set of XML files describing architectures and used by `gdbstub <GDB usage>`. 93* `host <https://gitlab.com/qemu-project/qemu/-/tree/master/host>`_: 94 Various architecture specific header files (crypto, atomic, memory 95 operations). 96* `linux-headers <https://gitlab.com/qemu-project/qemu/-/tree/master/linux-headers>`_: 97 A subset of headers imported from Linux kernel and used for implementing 98 KVM support and user-mode. 99* `linux-user <https://gitlab.com/qemu-project/qemu/-/tree/master/linux-user>`_: 100 `User mode <user-mode>` implementation. Contains one folder per target 101 architecture. 102* `.gitlab-ci.d <https://gitlab.com/qemu-project/qemu/-/tree/master/.gitlab-ci.d>`_: 103 `CI <ci>` yaml and scripts. 104* `include <https://gitlab.com/qemu-project/qemu/-/tree/master/include>`_: 105 All headers associated to different subsystems in QEMU. The hierarchy used 106 mirrors source code organization and naming. 107* `hw <https://gitlab.com/qemu-project/qemu/-/tree/master/hw>`_: 108 `Devices <device-emulation>` and boards emulation. Devices are categorized by 109 type/protocol/architecture and located in associated subfolder. 110* `io <https://gitlab.com/qemu-project/qemu/-/tree/master/io>`_: 111 QEMU `I/O channels <https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg04208.html>`_. 112* `libdecnumber <https://gitlab.com/qemu-project/qemu/-/tree/master/libdecnumber>`_: 113 Import of gcc library, used to implement decimal number arithmetic. 114* `migration <https://gitlab.com/qemu-project/qemu/-/tree/master/migration>`__: 115 :ref:`Migration framework <migration>`. 116* `monitor <https://gitlab.com/qemu-project/qemu/-/tree/master/monitor>`_: 117 `Monitor <QEMU monitor>` implementation (HMP & QMP). 118* `nbd <https://gitlab.com/qemu-project/qemu/-/tree/master/nbd>`_: 119 QEMU `NBD (Network Block Device) <nbd>` server. 120* `net <https://gitlab.com/qemu-project/qemu/-/tree/master/net>`_: 121 Network (host) support. 122* `pc-bios <https://gitlab.com/qemu-project/qemu/-/tree/master/pc-bios>`_: 123 Contains pre-built firmware binaries and boot images, ready to use in 124 QEMU without compilation. 125* `plugins <https://gitlab.com/qemu-project/qemu/-/tree/master/plugins>`_: 126 :ref:`TCG plugins <tcg-plugins>` core implementation. Plugins can be found in 127 `tests <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/tcg/plugins>`__ 128 and `contrib <https://gitlab.com/qemu-project/qemu/-/tree/master/contrib/plugins>`__ 129 folders. 130* `po <https://gitlab.com/qemu-project/qemu/-/tree/master/po>`_: 131 Translation files. 132* `python <https://gitlab.com/qemu-project/qemu/-/tree/master/python>`_: 133 Python part of our build/test system. 134* `qapi <https://gitlab.com/qemu-project/qemu/-/tree/master/qapi>`_: 135 `QAPI <qapi>` implementation. 136* `qobject <https://gitlab.com/qemu-project/qemu/-/tree/master/qobject>`_: 137 QEMU Object implementation. 138* `qga <https://gitlab.com/qemu-project/qemu/-/tree/master/qga>`_: 139 QEMU `Guest agent <qemu-ga>` implementation. 140* `qom <https://gitlab.com/qemu-project/qemu/-/tree/master/qom>`_: 141 QEMU :ref:`Object model <qom>` implementation, with monitor associated commands. 142* `replay <https://gitlab.com/qemu-project/qemu/-/tree/master/replay>`_: 143 QEMU :ref:`Record/replay <replay>` implementation. 144* `roms <https://gitlab.com/qemu-project/qemu/-/tree/master/roms>`_: 145 Contains source code for various firmware and ROMs, which can be compiled if 146 custom or updated versions are needed. 147* `rust <https://gitlab.com/qemu-project/qemu/-/tree/master/rust>`_: 148 Rust integration in QEMU. It contains the new interfaces defined and 149 associated devices using it. 150* `scripts <https://gitlab.com/qemu-project/qemu/-/tree/master/scripts>`_: 151 Collection of scripts used in build and test systems, and various 152 tools for QEMU codebase and execution traces. 153* `scsi <https://gitlab.com/qemu-project/qemu/-/tree/master/scsi>`_: 154 Code related to SCSI support, used by SCSI devices. 155* `semihosting <https://gitlab.com/qemu-project/qemu/-/tree/master/semihosting>`_: 156 QEMU `Semihosting <Semihosting>` implementation. 157* `stats <https://gitlab.com/qemu-project/qemu/-/tree/master/stats>`_: 158 `Monitor <QEMU monitor>` stats commands implementation. 159* `storage-daemon <https://gitlab.com/qemu-project/qemu/-/tree/master/storage-daemon>`_: 160 QEMU `Storage daemon <storage-daemon>` implementation. 161* `stubs <https://gitlab.com/qemu-project/qemu/-/tree/master/stubs>`_: 162 Various stubs (empty functions) used to compile QEMU with specific 163 configurations. 164* `subprojects <https://gitlab.com/qemu-project/qemu/-/tree/master/subprojects>`_: 165 QEMU submodules used by QEMU build system. 166* `system <https://gitlab.com/qemu-project/qemu/-/tree/master/system>`_: 167 QEMU `system mode <System emulation>` implementation (cpu, mmu, boot support). 168* `target <https://gitlab.com/qemu-project/qemu/-/tree/master/target>`_: 169 Contains code for all target architectures supported (one subfolder 170 per arch). For every architecture, you can find accelerator specific 171 implementations. 172* `tcg <https://gitlab.com/qemu-project/qemu/-/tree/master/tcg>`_: 173 :ref:`TCG <tcg>` related code. 174 Contains one subfolder per host supported architecture. 175* `tests <https://gitlab.com/qemu-project/qemu/-/tree/master/tests>`_: 176 QEMU `test <testing>` suite 177 178 - `avocado <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/avocado>`_: 179 Functional tests booting full VM using `Avocado framework <checkavocado-ref>`. 180 Those tests will be transformed and moved into 181 `tests/functional <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/functional>`_ 182 in the future. 183 - `data <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/data>`_: 184 Data for various tests. 185 - `decode <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/decode>`_: 186 Testsuite for :ref:`decodetree <decodetree>` implementation. 187 - `docker <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/docker>`_: 188 Code and scripts to create `containers <container-ref>` used in `CI <ci>`. 189 - `fp <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/fp>`_: 190 QEMU testsuite for soft float implementation. 191 - `functional <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/functional>`_: 192 `Functional tests <checkfunctional-ref>` (full VM boot). 193 - `lcitool <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/lcitool>`_: 194 Generate dockerfiles for CI containers. 195 - `migration <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/migration>`_: 196 Test scripts and data for :ref:`Migration framework <migration>`. 197 - `multiboot <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/multiboot>`_: 198 Test multiboot functionality for x86_64/i386. 199 - `qapi-schema <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/qapi-schema>`_: 200 Test scripts and data for `QAPI <qapi-tests>`. 201 - `qemu-iotests <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/qemu-iotests>`_: 202 `Disk image and block tests <qemu-iotests>`. 203 - `qtest <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/qtest>`_: 204 `Device emulation testing <qtest>`. 205 - `tcg <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/tcg>`__: 206 `TCG related tests <checktcg-ref>`. Contains code per architecture 207 (subfolder) and multiarch tests as well. 208 - `tsan <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/tsan>`_: 209 `Suppressions <tsan-suppressions>` for thread sanitizer. 210 - `uefi-test-tools <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/uefi-test-tools>`_: 211 Test tool for UEFI support. 212 - `unit <https://gitlab.com/qemu-project/qemu/-/tree/master/tests/unit>`_: 213 QEMU `Unit tests <unit-tests>`. 214* `trace <https://gitlab.com/qemu-project/qemu/-/tree/master/trace>`_: 215 :ref:`Tracing framework <tracing>`. Used to print information associated to various 216 events during execution. 217* `ui <https://gitlab.com/qemu-project/qemu/-/tree/master/ui>`_: 218 QEMU User interfaces. 219* `util <https://gitlab.com/qemu-project/qemu/-/tree/master/util>`_: 220 Utility code used by other parts of QEMU. 221