On 4/7/25 16:45, Kohei Tokunaga wrote:
Emscripten's fiber does not support submitting coroutines to other
threads.
Does it work as long as the thread does not rewind?
diff --git a/hw/9pfs/9p-util-stub.c b/hw/9pfs/9p-util-stub.c
new file mode 100644
index 0000000000..57c89902ab
--- /dev/null
+++ b/hw/9pfs/9p-util-stub.c
@@ -0,0 +1,43 @@
+/*
+ * 9p utilities stub functions
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "9p-util.h"
+
+ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name,
+ void *value, size_t size)
+{
+ return -1;
+}
+
+ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
+ char *list, size_t size)
+{
+ return -1;
+}
+
+ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
+ const char *name)
+{
+ return -1;
+}
+
+int fsetxattrat_nofollow(int dirfd, const char *path, const char *name,
+ void *value, size_t size, int flags)
+{
+ return -1;
+
+}
+
+int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
+{
+ return -1;
+}
+
+ssize_t fgetxattr(int fd, const char *name, void *value, size_t size)
+{
+ return -1;
+}
You can add all these to the stubs/emscripten.c file that I suggested
elsewhere.
diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h
index 7bc4ec8e85..8c5006fcdc 100644
--- a/hw/9pfs/9p-util.h
+++ b/hw/9pfs/9p-util.h
@@ -84,6 +84,24 @@ static inline int errno_to_dotl(int err) {
} else if (err == EOPNOTSUPP) {
err = 95; /* ==EOPNOTSUPP on Linux */
}
+#elif defined(EMSCRIPTEN)
+ /*
+ * FIXME: Only most important errnos translated here yet, this should be
+ * extended to as many errnos being translated as possible in future.
+ */
+ if (err == ENAMETOOLONG) {
+ err = 36; /* ==ENAMETOOLONG on Linux */
+ } else if (err == ENOTEMPTY) {
+ err = 39; /* ==ENOTEMPTY on Linux */
+ } else if (err == ELOOP) {
+ err = 40; /* ==ELOOP on Linux */
+ } else if (err == ENODATA) {
+ err = 61; /* ==ENODATA on Linux */
+ } else if (err == ENOTSUP) {
+ err = 95; /* ==EOPNOTSUPP on Linux */
+ } else if (err == EOPNOTSUPP) {
+ err = 95; /* ==EOPNOTSUPP on Linux */
+ }
#else
#error Missing errno translation to Linux for this host system
#endif
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 7cad2bce62..4f45f0edd3 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -4013,6 +4013,9 @@ out_nofid:
* Linux guests.
*/
#define P9_XATTR_SIZE_MAX 65536
+#elif defined(EMSCRIPTEN)
+/* No support for xattr */
+#define P9_XATTR_SIZE_MAX 0
#else
#error Missing definition for P9_XATTR_SIZE_MAX for this host system
#endif
diff --git a/hw/9pfs/coth.h b/hw/9pfs/coth.h
index 2c54249b35..7b0d05ba1b 100644
--- a/hw/9pfs/coth.h
+++ b/hw/9pfs/coth.h
@@ -19,6 +19,7 @@
#include "qemu/coroutine-core.h"
#include "9p.h"
+#ifndef EMSCRIPTEN
/*
* we want to use bottom half because we want to make sure the below
* sequence of events.
@@ -57,6 +58,17 @@
/* re-enter back to qemu thread */ \
qemu_coroutine_yield(); \
} while (0)
+#else
+/*
+ * FIXME: implement this on emscripten but emscripten's coroutine
+ * implementation (fiber) doesn't support submitting a coroutine to other
+ * threads.
+ */
+#define v9fs_co_run_in_worker(code_block) \
+ do { \
+ code_block; \
+ } while (0)
+#endif
You could extracting v9fs_co_run_in_worker()'s bodies into separate
functions. It is tedious but not hard; all you have to do is define
structs for the to parameters and return values of v9fs_co_*(), unpack
them in the callback functions, and retrieve the return value in
v9fs_co_*(). Many functions
The advantage is that, instead of all the bottom half and yielding dance
that is done by v9fs_co_run_in_worker() and co_run_in_worker_bh(), you
can just use thread_pool_submit_co().
Paolo
void co_run_in_worker_bh(void *);
int coroutine_fn v9fs_co_readlink(V9fsPDU *, V9fsPath *, V9fsString *);
diff --git a/hw/9pfs/meson.build b/hw/9pfs/meson.build
index d35d4f44ff..04f85fb9e9 100644
--- a/hw/9pfs/meson.build
+++ b/hw/9pfs/meson.build
@@ -17,6 +17,8 @@ if host_os == 'darwin'
fs_ss.add(files('9p-util-darwin.c'))
elif host_os == 'linux'
fs_ss.add(files('9p-util-linux.c'))
+elif host_os == 'emscripten'
+ fs_ss.add(files('9p-util-stub.c'))
endif
fs_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xen-9p-backend.c'))
system_ss.add_all(when: 'CONFIG_FSDEV_9P', if_true: fs_ss)
diff --git a/meson.build b/meson.build
index ab84820bc5..a3aadf8b59 100644
--- a/meson.build
+++ b/meson.build
@@ -2356,11 +2356,11 @@ dbus_display = get_option('dbus_display') \
.allowed()
have_virtfs = get_option('virtfs') \
- .require(host_os == 'linux' or host_os == 'darwin',
+ .require(host_os == 'linux' or host_os == 'darwin' or host_os ==
'emscripten',
error_message: 'virtio-9p (virtfs) requires Linux or macOS') \
- .require(host_os == 'linux' or cc.has_function('pthread_fchdir_np'),
+ .require(host_os == 'linux' or host_os == 'emscripten' or
cc.has_function('pthread_fchdir_np'),
error_message: 'virtio-9p (virtfs) on macOS requires the
presence of pthread_fchdir_np') \
- .require(host_os == 'darwin' or libattr.found(),
+ .require(host_os == 'darwin' or host_os == 'emscripten' or libattr.found(),
error_message: 'virtio-9p (virtfs) on Linux requires
libattr-devel') \
.disable_auto_if(not have_tools and not have_system) \
.allowed()
