Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* ci: enable RISC-V cross jobs * rust: bump minimum supported version to 1.77 * rust: enable uninlined_format_args lint * initial Emscripten support * small fixes # -----BEGIN PGP SIGNATURE----- # # iQFIBAABCgAyFiEE8TM4V0tmI4mGbHaCv/vSX3jHroMFAmgaFq8UHHBib256aW5p # QHJlZGhhdC5jb20ACgkQv/vSX3jHroOxAAf/YPKw5KAoE5SwUqJ0oSOMHrU0w4jc # A2Qiw1uziA6kDmUMUXwWR7Qbd8V7jtihGrgTrIPopeavgWWQeNsBHjN4WxHRI7aq # +429rjzFo9V9tSfgp6UcLQSk/9kC4ygEwPnesHpKd27fS6z9Wg4AQkj1iFipR179 # wC3fqwOqqWZSjfUd7wjo7McFYZgL5j/cxmFXePh8+fdT+6PUKdG9nRW86KUPDZ+A # 8HxcuOW7GZd+LhnYUhi7vlLFo/RgVsGQWj0Q4BDJvUkKa13t9UUCGff7uQP2AC3v # ny0gWDcmbWY1L/QXyNzhgd44X4LAjCmpnonlYnrdZizEmhv3aByd+fANgw== # =uIJK # -----END PGP SIGNATURE----- # gpg: Signature made Tue 06 May 2025 10:03:27 EDT # gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83 # gpg: issuer "pbonzini@redhat.com" # gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full] # gpg: aka "Paolo Bonzini <pbonzini@redhat.com>" [full] # Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1 # Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83 * tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (30 commits) gitlab: Enable CI for wasm build tests: Add Dockerfile containing dependencies for Emscripten build meson: Add wasm build in build scripts util: Add coroutine backend for emscripten util: exclude mmap-alloc.c from compilation target on Emscripten Disable options unsupported on Emscripten include/qemu/osdep.h: Add Emscripten-specific OS dependencies block: Fix type conflict of the copy_file_range stub block: Add including of ioctl header for Emscripten build util/cacheflush.c: Update cache flushing mechanism for Emscripten include/glib-compat.h: Poison g_list_sort and g_slist_sort target/s390x: Fix type conflict of GLib function pointers target/ppc: Fix type conflict of GLib function pointers target/i386/cpu.c: Fix type conflict of GLib function pointers target/arm/helper.c: Fix type conflict of GLib function pointers docs: build-system: fix typo ci: run RISC-V cross jobs by default rust: clippy: enable uninlined_format_args lint target/i386/emulate: fix target_ulong format strings docs: rust: update for newer minimum supported version ... Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2026-07-06 00:20:22 -07:00 · 2025-05-07 16:10:59 -04:00
parent 57b6f8d07f e6b9b79c30
commit c5f122fdcc
78 changed files with 861 additions and 654 deletions
@@ -115,3 +115,30 @@
    - du -chs ${CI_PROJECT_DIR}/*-cache
  variables:
    QEMU_JOB_FUNCTIONAL: 1
+
+.wasm_build_job_template:
+  extends: .base_job_template
+  stage: build
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
+  before_script:
+    - source scripts/ci/gitlab-ci-section
+    - section_start setup "Pre-script setup"
+    - JOBS=$(expr $(nproc) + 1)
+    - section_end setup
+  script:
+    - du -sh .git
+    - mkdir build
+    - cd build
+    - section_start configure "Running configure"
+    - emconfigure ../configure --disable-docs
+          ${TARGETS:+--target-list="$TARGETS"}
+          $CONFIGURE_ARGS ||
+      { cat config.log meson-logs/meson-log.txt && exit 1; }
+    - if test -n "$LD_JOBS";
+      then
+        pyvenv/bin/meson configure . -Dbackend_max_links="$LD_JOBS" ;
+      fi || exit 1;
+    - section_end configure
+    - section_start build "Building QEMU"
+    - emmake make -j"$JOBS"
+    - section_end build
@@ -792,3 +792,12 @@ coverity:
      when: never
    # Always manual on forks even if $QEMU_CI == "2"
    - when: manual
+
+build-wasm:
+  extends: .wasm_build_job_template
+  timeout: 2h
+  needs:
+    job: wasm-emsdk-cross-container
+  variables:
+    IMAGE: emsdk-wasm32-cross
+    CONFIGURE_ARGS: --static --disable-tools --enable-debug --enable-tcg-interpreter
@@ -67,11 +67,8 @@ ppc64el-debian-cross-container:
 riscv64-debian-cross-container:
  extends: .container_job_template
  stage: containers
-  # as we are currently based on 'sid/unstable' we may break so...
-  allow_failure: true
  variables:
    NAME: debian-riscv64-cross
-    QEMU_JOB_OPTIONAL: 1

 s390x-debian-cross-container:
  extends: .container_job_template
@@ -94,3 +91,8 @@ win64-fedora-cross-container:
  extends: .container_job_template
  variables:
    NAME: fedora-win64-cross
+
+wasm-emsdk-cross-container:
+  extends: .container_job_template
+  variables:
+    NAME: emsdk-wasm32-cross
@@ -118,12 +118,8 @@ cross-ppc64el-kvm-only:
    IMAGE: debian-ppc64el-cross
    EXTRA_CONFIGURE_OPTS: --disable-tcg --without-default-devices

-# The riscv64 cross-builds currently use a 'sid' container to get
-# compilers and libraries. Until something more stable is found we
-# allow_failure so as not to block CI.
 cross-riscv64-system:
  extends: .cross_system_build_job
-  allow_failure: true
  needs:
    job: riscv64-debian-cross-container
  variables:
@@ -131,7 +127,6 @@ cross-riscv64-system:

 cross-riscv64-user:
  extends: .cross_user_build_job
-  allow_failure: true
  needs:
    job: riscv64-debian-cross-container
  variables:
@@ -627,6 +627,15 @@ F: .gitlab-ci.d/cirrus/macos-*
 F: */*.m
 F: scripts/entitlement.sh

+WebAssembly
+M: Kohei Tokunaga <ktokunaga.mail@gmail.com>
+S: Maintained
+F: include/system/os-wasm.h
+F: os-wasm.c
+F: util/coroutine-wasm.c
+F: configs/meson/emscripten.txt
+F: tests/docker/dockerfiles/emsdk-wasm32-cross.docker
+
 Alpha Machines
 --------------
 M: Richard Henderson <richard.henderson@linaro.org>
@@ -12,8 +12,10 @@ system_ss.add([files(

 if host_os != 'windows'
  system_ss.add(files('rng-random.c'))
-  system_ss.add(files('hostmem-file.c'))
-  system_ss.add([files('hostmem-shm.c'), rt])
+  if host_os != 'emscripten'
+    system_ss.add(files('hostmem-file.c'))
+    system_ss.add([files('hostmem-shm.c'), rt])
+  endif
 endif
 if host_os == 'linux'
  system_ss.add(files('hostmem-memfd.c'))
@@ -110,6 +110,10 @@
 #include <sys/diskslice.h>
 #endif

+#ifdef EMSCRIPTEN
+#include <sys/ioctl.h>
+#endif
+
 /* OS X does not have O_DSYNC */
 #ifndef O_DSYNC
 #ifdef O_SYNC
@@ -2076,8 +2080,11 @@ static int handle_aiocb_write_zeroes_unmap(void *opaque)
 }

 #ifndef HAVE_COPY_FILE_RANGE
-static off_t copy_file_range(int in_fd, off_t *in_off, int out_fd,
-                             off_t *out_off, size_t len, unsigned int flags)
+#ifndef EMSCRIPTEN
+static
+#endif
+ssize_t copy_file_range(int in_fd, off_t *in_off, int out_fd,
+                        off_t *out_off, size_t len, unsigned int flags)
 {
 #ifdef __NR_copy_file_range
    return syscall(__NR_copy_file_range, in_fd, in_off, out_fd,
@@ -0,0 +1,8 @@
+[built-in options]
+c_args = ['-pthread']
+cpp_args = ['-pthread']
+objc_args = ['-pthread']
+# -sPROXY_TO_PTHREAD link time flag always requires -pthread even during
+# configuration so explicitly add the flag here.
+c_link_args = ['-pthread','-sASYNCIFY=1','-sPROXY_TO_PTHREAD=1','-sFORCE_FILESYSTEM','-sALLOW_TABLE_GROWTH','-sTOTAL_MEMORY=2GB','-sWASM_BIGINT','-sEXPORT_ES6=1','-sASYNCIFY_IMPORTS=ffi_call_js','-sEXPORTED_RUNTIME_METHODS=addFunction,removeFunction,TTY,FS']
+cpp_link_args = ['-pthread','-sASYNCIFY=1','-sPROXY_TO_PTHREAD=1','-sFORCE_FILESYSTEM','-sALLOW_TABLE_GROWTH','-sTOTAL_MEMORY=2GB','-sWASM_BIGINT','-sEXPORT_ES6=1','-sASYNCIFY_IMPORTS=ffi_call_js','-sEXPORTED_RUNTIME_METHODS=addFunction,removeFunction,TTY,FS']
@@ -360,6 +360,10 @@ elif check_define __NetBSD__; then
  host_os=netbsd
 elif check_define __APPLE__; then
  host_os=darwin
+elif check_define EMSCRIPTEN ; then
+  host_os=emscripten
+  cpu=wasm32
+  cross_compile="yes"
 else
  # This is a fatal error, but don't report it yet, because we
  # might be going to just print the --help text, or it might
@@ -526,6 +530,9 @@ case "$cpu" in
    linux_arch=x86
    CPU_CFLAGS="-m64"
    ;;
+  wasm32)
+    CPU_CFLAGS="-m32"
+    ;;
 esac

 if test -n "$host_arch" && {
@@ -118,9 +118,14 @@ Rust build dependencies
  include bindgen or have an older version, it is recommended to install
  a newer version using ``cargo install bindgen-cli``.

-  Developers may want to use Cargo-based tools in the QEMU source tree;
-  this requires Cargo 1.74.0.  Note that Cargo is not required in order
-  to build QEMU.
+  QEMU requires Rust 1.77.0.  This is available on all supported platforms
+  with one exception, namely the ``mips64el`` architecture on Debian bookworm.
+  For all other architectures, Debian bookworm provides a new-enough Rust
+  compiler in the ``rustc-web`` package.
+
+  Also, on Ubuntu 22.04 or 24.04 this requires the ``rustc-1.77``
+  (or newer) package.  The path to ``rustc`` and ``rustdoc`` must be
+  provided manually to the configure script.

 Optional build dependencies
  Build components whose absence does not affect the ability to build QEMU
@@ -168,7 +168,7 @@ The required versions of the packages are stored in a configuration file
 ``pythondeps.toml``.  The format is custom to QEMU, but it is documented
 at the top of the file itself and it should be easy to understand.  The
 requirements should make it possible to use the version that is packaged
-that is provided by supported distros.
+by QEMU's supported distros.

 When dependencies are downloaded, instead, ``configure`` uses a "known
 good" version that is also listed in ``pythondeps.toml``.  In this
@@ -71,36 +71,9 @@ Building Rust code with ``--enable-modules`` is not supported yet.
 Supported tools
 '''''''''''''''

-QEMU supports rustc version 1.63.0 and newer.  Notably, the following features
+QEMU supports rustc version 1.77.0 and newer.  Notably, the following features
 are missing:

-* ``core::ffi`` (1.64.0).  Use ``std::os::raw`` and ``std::ffi`` instead.
-
-* ``cast_mut()``/``cast_const()`` (1.65.0).  Use ``as`` instead.
-
-* "let ... else" (1.65.0).  Use ``if let`` instead.  This is currently patched
-  in QEMU's vendored copy of the bilge crate.
-
-* Generic Associated Types (1.65.0)
-
-* ``CStr::from_bytes_with_nul()`` as a ``const`` function (1.72.0).
-
-* "Return position ``impl Trait`` in Traits" (1.75.0, blocker for including
-  the pinned-init create).
-
-* ``MaybeUninit::zeroed()`` as a ``const`` function (1.75.0).  QEMU's
-  ``Zeroable`` trait can be implemented without ``MaybeUninit::zeroed()``,
-  so this would be just a cleanup.
-
-* ``c"" literals`` (stable in 1.77.0).  QEMU provides a ``c_str!()`` macro
-  to define ``CStr`` constants easily
-
-* ``offset_of!`` (stable in 1.77.0).  QEMU uses ``offset_of!()`` heavily; it
-  provides a replacement in the ``qemu_api`` crate, but it does not support
-  lifetime parameters and therefore ``&'a Something`` fields in the struct
-  may have to be replaced by ``NonNull<Something>``.  *Nested* ``offset_of!``
-  was only stabilized in Rust 1.82.0, but it is not used.
-
 * inline const expression (stable in 1.79.0), currently worked around with
  associated constants in the ``FnCall`` trait.

@@ -125,12 +98,6 @@ are missing:

 __ https://github.com/rust-lang/rust/pull/125258

-It is expected that QEMU will advance its minimum supported version of
-rustc to 1.77.0 as soon as possible; as of January 2025, blockers
-for that right now are Debian bookworm and 32-bit MIPS processors.
-This unfortunately means that references to statics in constants will
-remain an issue.
-
 QEMU also supports version 0.60.x of bindgen, which is missing option
 ``--generate-cstr``.  This option requires version 0.66.x and will
 be adopted as soon as supporting these older versions is not necessary
@@ -183,7 +150,6 @@ module           status
 ``bitops``       complete
 ``callbacks``    complete
 ``cell``         stable
-``c_str``        complete
 ``errno``        complete
 ``irq``          complete
 ``memory``       stable
@@ -440,7 +406,7 @@ Adding dependencies
 Generally, the set of dependent crates is kept small.  Think twice before
 adding a new external crate, especially if it comes with a large set of
 dependencies itself.  Sometimes QEMU only needs a small subset of the
-functionality; see for example QEMU's ``assertions`` or ``c_str`` modules.
+functionality; see for example QEMU's ``assertions`` module.

 On top of this recommendation, adding external crates to QEMU is a
 slightly complicated process, mostly due to the need to teach Meson how
@@ -36,6 +36,13 @@
 #include <pwd.h>
 #endif

+/*
+ * These functions perform function pointer casts which can cause function call
+ * failure on Emscripten. Use g_slist_sort_with_data and g_list_sort_with_data
+ * instead of these functions.
+ */
+#pragma GCC poison g_slist_sort g_list_sort
+
 /*
 * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
 * use of functions from newer GLib via this compat header needs a little
@@ -26,6 +26,13 @@ static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)
    /* icache is coherent and does not require flushing. */
 }

+#elif defined(EMSCRIPTEN)
+
+static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)
+{
+    /* Wasm doesn't have executable region of memory. */
+}
+
 #else

 void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len);
@@ -8,7 +8,7 @@
 * To avoid getting into possible circular include dependencies, this
 * file should not include any other QEMU headers, with the exceptions
 * of config-host.h, config-target.h, qemu/compiler.h,
- * system/os-posix.h, system/os-win32.h, glib-compat.h and
+ * system/os-posix.h, system/os-win32.h, system/os-wasm.h, glib-compat.h and
 * qemu/typedefs.h, all of which are doing a similar job to this file
 * and are under similar constraints.
 *
@@ -164,10 +164,14 @@ QEMU_EXTERN_C int daemon(int, int);
 #include "system/os-win32.h"
 #endif

-#ifdef CONFIG_POSIX
+#if defined(CONFIG_POSIX) && !defined(EMSCRIPTEN)
 #include "system/os-posix.h"
 #endif

+#if defined(EMSCRIPTEN)
+#include "system/os-wasm.h"
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * posix specific declarations forked from os-posix.h, removing functions not
+ * working on Emscripten
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2010 Jes Sorensen <Jes.Sorensen@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef QEMU_OS_WASM_H
+#define QEMU_OS_WASM_H
+
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <sys/un.h>
+
+#ifdef CONFIG_SYSMACROS
+#include <sys/sysmacros.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void os_set_line_buffering(void);
+void os_setup_early_signal_handling(void);
+void os_set_proc_name(const char *s);
+void os_setup_signal_handling(void);
+void os_setup_limits(void);
+void os_setup_post(void);
+int os_mlock(bool on_fault);
+static inline int os_set_daemonize(bool d)
+{
+    return -1;
+};
+bool is_daemonized(void);
+static inline void os_daemonize(void) {}
+
+/**
+ * qemu_alloc_stack:
+ * @sz: pointer to a size_t holding the requested usable stack size
+ *
+ * Allocate memory that can be used as a stack, for instance for
+ * coroutines. If the memory cannot be allocated, this function
+ * will abort (like g_malloc()). This function also inserts an
+ * additional guard page to catch a potential stack overflow.
+ * Note that the memory required for the guard page and alignment
+ * and minimal stack size restrictions will increase the value of sz.
+ *
+ * The allocated stack must be freed with qemu_free_stack().
+ *
+ * Returns: pointer to (the lowest address of) the stack memory.
+ */
+void *qemu_alloc_stack(size_t *sz);
+
+/**
+ * qemu_free_stack:
+ * @stack: stack to free
+ * @sz: size of stack in bytes
+ *
+ * Free a stack allocated via qemu_alloc_stack(). Note that sz must
+ * be exactly the adjusted stack size returned by qemu_alloc_stack.
+ */
+void qemu_free_stack(void *stack, size_t sz);
+
+/* POSIX and Mingw32 differ in the name of the stdio lock functions.  */
+
+static inline void qemu_flockfile(FILE *f)
+{
+    flockfile(f);
+}
+
+static inline void qemu_funlockfile(FILE *f)
+{
+    funlockfile(f);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
@@ -50,9 +50,9 @@ genh = []
 qapi_trace_events = []

 bsd_oses = ['gnu/kfreebsd', 'freebsd', 'netbsd', 'openbsd', 'dragonfly', 'darwin']
-supported_oses = ['windows', 'freebsd', 'netbsd', 'openbsd', 'darwin', 'sunos', 'linux']
+supported_oses = ['windows', 'freebsd', 'netbsd', 'openbsd', 'darwin', 'sunos', 'linux', 'emscripten']
 supported_cpus = ['ppc', 'ppc64', 's390x', 'riscv32', 'riscv64', 'x86', 'x86_64',
-  'arm', 'aarch64', 'loongarch64', 'mips', 'mips64', 'sparc64']
+  'arm', 'aarch64', 'loongarch64', 'mips', 'mips64', 'sparc64', 'wasm32']

 cpu = host_machine.cpu_family()

@@ -94,12 +94,12 @@ have_rust = have_rust and add_languages('rust', native: true,
    required: get_option('rust').disable_auto_if(not have_system))
 if have_rust
  rustc = meson.get_compiler('rust')
-  if rustc.version().version_compare('<1.63.0')
+  if rustc.version().version_compare('<1.77.0')
    if get_option('rust').enabled()
-      error('rustc version ' + rustc.version() + ' is unsupported. Please upgrade to at least 1.63.0')
+      error('rustc version ' + rustc.version() + ' is unsupported. Please upgrade to at least 1.77.0')
    else
      warning('rustc version ' + rustc.version() + ' is unsupported, disabling Rust compilation.')
-      message('Please upgrade to at least 1.63.0 to use Rust.')
+      message('Please upgrade to at least 1.77.0 to use Rust.')
      have_rust = false
    endif
  endif
@@ -353,6 +353,8 @@ foreach lang : all_languages
      # endif
      #endif''')
    # ok
+  elif compiler.get_id() == 'emscripten'
+    # ok
  else
    error('You either need GCC v7.4 or Clang v10.0 (or XCode Clang v15.0) to compile QEMU')
  endif
@@ -470,7 +472,10 @@ endif
 # instead, we can't add -no-pie because it overrides -shared: the linker then
 # tries to build an executable instead of a shared library and fails.  So
 # don't add -no-pie anywhere and cross fingers. :(
-if not get_option('b_pie')
+#
+# Emscripten doesn't support -no-pie but meson can't catch the compiler
+# warning. So explicitly omit the flag for Emscripten.
+if not get_option('b_pie') and host_os != 'emscripten'
  qemu_common_flags += cc.get_supported_arguments('-fno-pie', '-no-pie')
 endif

@@ -514,6 +519,8 @@ ucontext_probe = '''
 supported_backends = []
 if host_os == 'windows'
  supported_backends += ['windows']
+elif host_os == 'emscripten'
+  supported_backends += ['wasm']
 else
  if host_os != 'darwin' and cc.links(ucontext_probe)
    supported_backends += ['ucontext']
@@ -902,6 +909,10 @@ if get_option('tcg').allowed()
    if not get_option('tcg_interpreter')
      error('Unsupported CPU @0@, try --enable-tcg-interpreter'.format(cpu))
    endif
+  elif host_arch == 'wasm32'
+    if not get_option('tcg_interpreter')
+      error('WebAssembly host requires --enable-tcg-interpreter')
+    endif
  elif get_option('tcg_interpreter')
    warning('Use of the TCG interpreter is not recommended on this host')
    warning('architecture. There is a native TCG execution backend available')
@@ -2962,7 +2973,9 @@ config_host_data.set('CONFIG_ATOMIC64', cc.links('''
    return 0;
  }''', args: qemu_isa_flags))

-has_int128_type = cc.compiles('''
+# has_int128_type is set to false on Emscripten to avoid errors by libffi
+# during runtime.
+has_int128_type = host_os != 'emscripten' and cc.compiles('''
  __int128_t a;
  __uint128_t b;
  int main(void) { b = a; }''')
@@ -3775,6 +3788,8 @@ if have_block
  # os-win32.c does not
  if host_os == 'windows'
    system_ss.add(files('os-win32.c'))
+  elif host_os == 'emscripten'
+    blockdev_ss.add(files('os-wasm.c'))
  else
    blockdev_ss.add(files('os-posix.c'))
  endif
@@ -4516,7 +4531,11 @@ subdir('scripts')
 subdir('tools')
 subdir('pc-bios')
 subdir('docs')
-subdir('tests')
+# Tests are disabled on emscripten because they rely on host features that aren't
+# supported by emscripten (e.g. fork and unix socket).
+if host_os != 'emscripten'
+  subdir('tests')
+endif
 if gtk.found()
  subdir('po')
 endif
@@ -34,7 +34,7 @@ option('fuzzing_engine', type : 'string', value : '',
 option('trace_file', type: 'string', value: 'trace',
       description: 'Trace file prefix for simple backend')
 option('coroutine_backend', type: 'combo',
-       choices: ['ucontext', 'sigaltstack', 'windows', 'auto'],
+       choices: ['ucontext', 'sigaltstack', 'windows', 'wasm', 'auto'],
       value: 'auto', description: 'coroutine backend to use')

 # Everything else can be set via --enable/--disable-* option
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * os-wasm.c
+ * Forked from os-posix.c, removing functions not working on Emscripten
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2010 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <pwd.h>
+#include <grp.h>
+#include <libgen.h>
+
+#include "qemu/error-report.h"
+#include "qemu/log.h"
+#include "system/runstate.h"
+#include "qemu/cutils.h"
+
+void os_setup_post(void){}
+void os_set_line_buffering(void)
+{
+    setvbuf(stdout, NULL, _IOLBF, 0);
+}
+void os_setup_early_signal_handling(void)
+{
+    struct sigaction act;
+    sigfillset(&act.sa_mask);
+    act.sa_flags = 0;
+    act.sa_handler = SIG_IGN;
+    sigaction(SIGPIPE, &act, NULL);
+}
+void os_set_proc_name(const char *s)
+{
+    error_report("Change of process name not supported by your OS");
+    exit(1);
+}
+static void termsig_handler(int signal, siginfo_t *info, void *c)
+{
+    qemu_system_killed(info->si_signo, info->si_pid);
+}
+
+void os_setup_signal_handling(void)
+{
+    struct sigaction act;
+
+    memset(&act, 0, sizeof(act));
+    act.sa_sigaction = termsig_handler;
+    act.sa_flags = SA_SIGINFO;
+    sigaction(SIGINT,  &act, NULL);
+    sigaction(SIGHUP,  &act, NULL);
+    sigaction(SIGTERM, &act, NULL);
+}
+void os_setup_limits(void)
+{
+    struct rlimit nofile;
+
+    if (getrlimit(RLIMIT_NOFILE, &nofile) < 0) {
+        warn_report("unable to query NOFILE limit: %s", strerror(errno));
+        return;
+    }
+
+    if (nofile.rlim_cur == nofile.rlim_max) {
+        return;
+    }
+
+    nofile.rlim_cur = nofile.rlim_max;
+
+    if (setrlimit(RLIMIT_NOFILE, &nofile) < 0) {
+        warn_report("unable to set NOFILE limit: %s", strerror(errno));
+        return;
+    }
+}
+int os_mlock(bool on_fault)
+{
+#ifdef HAVE_MLOCKALL
+    int ret = 0;
+    int flags = MCL_CURRENT | MCL_FUTURE;
+
+    if (on_fault) {
+#ifdef HAVE_MLOCK_ONFAULT
+        flags |= MCL_ONFAULT;
+#else
+        error_report("mlockall: on_fault not supported");
+        return -EINVAL;
+#endif
+    }
+
+    ret = mlockall(flags);
+    if (ret < 0) {
+        error_report("mlockall: %s", strerror(errno));
+    }
+
+    return ret;
+#else
+    (void)on_fault;
+    return -ENOSYS;
+#endif
+}
@@ -4862,7 +4862,7 @@ SRST
    Start right away with a saved state (``loadvm`` in monitor)
 ERST

-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(EMSCRIPTEN)
 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
    "-daemonize      daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
 #endif
@@ -5249,7 +5249,7 @@ HXCOMM Internal use
 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)

-#ifdef CONFIG_POSIX
+#if defined(CONFIG_POSIX) && !defined(EMSCRIPTEN)
 DEF("run-with", HAS_ARG, QEMU_OPTION_run_with,
    "-run-with [async-teardown=on|off][,chroot=dir][user=username|uid:gid]\n"
    "                Set miscellaneous QEMU process lifecycle options:\n"
--- a/Show More
+++ b/Show More