| Message ID | 97a2164b3f428265136bb1c01615a16b516138c2.1744787186.git.ktokunaga.mail@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Enable QEMU TCI to run 32bit guests on browsers | expand |
The "why?" isn't clearly described. On 16/4/25 10:14, Kohei Tokunaga wrote: > Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com> > --- > include/qemu/cacheflush.h | 3 ++- > util/cacheflush.c | 3 ++- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/qemu/cacheflush.h b/include/qemu/cacheflush.h > index ae20bcda73..84969801e3 100644 > --- a/include/qemu/cacheflush.h > +++ b/include/qemu/cacheflush.h > @@ -19,7 +19,8 @@ > * mappings of the same physical page(s). > */ > > -#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) > +#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) \ > + || defined(EMSCRIPTEN) > > static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len) > { > diff --git a/util/cacheflush.c b/util/cacheflush.c > index 1d12899a39..e5aa256cd8 100644 > --- a/util/cacheflush.c > +++ b/util/cacheflush.c > @@ -225,7 +225,8 @@ static void __attribute__((constructor)) init_cache_info(void) > * Architecture (+ OS) specific cache flushing mechanisms. > */ > > -#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) > +#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) || \ > + defined(EMSCRIPTEN) > > /* Caches are coherent and do not require flushing; symbol inline. */ >
Hi Philippe, > The "why?" isn't clearly described. Although __builtin___clear_cache is used to flush the instruction cache for a specified memory region[1], this operation doesn't apply to wasm, as its memory isn't executable. Moreover, Emscripten does not support this builtin and fails to compile it with the following error. > fatal error: error in backend: llvm.clear_cache is not supported on wasm To resolve this, I've removed the call to __builtin___clear_cache. I'll update this patch to include an explicit "#elif" branch with an explanation, like the following: +#elif defined(EMSCRIPTEN) + +/* Wasm does not have an executable memory region. */ + Please let me know if I'm missing something or if there is a preferred way to handle this case. [1] https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005f_005f_005fclear_005fcache
On 17/4/25 11:27, Kohei Tokunaga wrote: > Hi Philippe, > > > The "why?" isn't clearly described. > I'm happy with the following ... > Although __builtin___clear_cache is used to flush the instruction cache for > a specified memory region[1], this operation doesn't apply to wasm, as its > memory isn't executable. Moreover, Emscripten does not support this builtin > and fails to compile it with the following error. > > > fatal error: error in backend: llvm.clear_cache is not supported on wasm > > To resolve this, I've removed the call to __builtin___clear_cache. ... used as commit description, > > I'll update this patch to include an explicit "#elif" branch with an > explanation, like the following: > > +#elif defined(EMSCRIPTEN) > + > +/* Wasm does not have an executable memory region. */ > + and this comment in the code. Thanks! > > Please let me know if I'm missing something or if there is a preferred way > to handle this case. > > [1] https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Other- > Builtins.html#index-_005f_005fbuiltin_005f_005f_005fclear_005fcache > <https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Other- > Builtins.html#index-_005f_005fbuiltin_005f_005f_005fclear_005fcache> >
diff --git a/include/qemu/cacheflush.h b/include/qemu/cacheflush.h index ae20bcda73..84969801e3 100644 --- a/include/qemu/cacheflush.h +++ b/include/qemu/cacheflush.h @@ -19,7 +19,8 @@ * mappings of the same physical page(s). */ -#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) +#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) \ + || defined(EMSCRIPTEN) static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len) { diff --git a/util/cacheflush.c b/util/cacheflush.c index 1d12899a39..e5aa256cd8 100644 --- a/util/cacheflush.c +++ b/util/cacheflush.c @@ -225,7 +225,8 @@ static void __attribute__((constructor)) init_cache_info(void) * Architecture (+ OS) specific cache flushing mechanisms. */ -#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) +#if defined(__i386__) || defined(__x86_64__) || defined(__s390__) || \ + defined(EMSCRIPTEN) /* Caches are coherent and do not require flushing; symbol inline. */
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com> --- include/qemu/cacheflush.h | 3 ++- util/cacheflush.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-)