{"id":2075146,"url":"http://patchwork.ozlabs.org/api/patches/2075146/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/73301cc216217d5c3e0d7acdd32482e36f4f045c.1745295397.git.ktokunaga.mail@gmail.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<73301cc216217d5c3e0d7acdd32482e36f4f045c.1745295397.git.ktokunaga.mail@gmail.com>","list_archive_url":null,"date":"2025-04-22T05:27:15","name":"[v2,11/20] util/cacheflush.c: Update cache flushing mechanism for Emscripten","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"bd8ff46333298c9e8c211e8126c8365010766730","submitter":{"id":90637,"url":"http://patchwork.ozlabs.org/api/people/90637/?format=json","name":"Kohei Tokunaga","email":"ktokunaga.mail@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/73301cc216217d5c3e0d7acdd32482e36f4f045c.1745295397.git.ktokunaga.mail@gmail.com/mbox/","series":[{"id":453631,"url":"http://patchwork.ozlabs.org/api/series/453631/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=453631","date":"2025-04-22T05:27:04","name":"Enable QEMU TCI to run 32bit guests on browsers","version":2,"mbox":"http://patchwork.ozlabs.org/series/453631/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2075146/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2075146/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20230601 header.b=JWdkG5Ho;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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helo=mail-pl1-x636.google.com","X-Spam_score_int":"-20","X-Spam_score":"-2.1","X-Spam_bar":"--","X-Spam_report":"(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Although __builtin___clear_cache is used to flush the instruction cache for\na specified memory region[1], this operation doesn't apply to wasm, as its\nmemory isn't executable. Moreover, Emscripten does not support this builtin\nand fails to compile it with the following error.\n\n> fatal error: error in backend: llvm.clear_cache is not supported on wasm\n\nTo resolve this, this commit removes the call to __builtin___clear_cache for\nEmscripten build.\n\n[1] https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005f_005f_005fclear_005fcache\n\nSigned-off-by: Kohei Tokunaga \n---\n include/qemu/cacheflush.h | 7 +++++++\n util/cacheflush.c | 4 ++++\n 2 files changed, 11 insertions(+)\n\nV2:\n- Added an explanation for the change to both the code comment and the\n commit message.","diff":"diff --git a/include/qemu/cacheflush.h b/include/qemu/cacheflush.h\nindex ae20bcda73..76eb55d818 100644\n--- a/include/qemu/cacheflush.h\n+++ b/include/qemu/cacheflush.h\n@@ -26,6 +26,13 @@ static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)\n /* icache is coherent and does not require flushing. */\n }\n \n+#elif defined(EMSCRIPTEN)\n+\n+static inline void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)\n+{\n+ /* Wasm doesn't have executable region of memory. */\n+}\n+\n #else\n \n void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len);\ndiff --git a/util/cacheflush.c b/util/cacheflush.c\nindex 1d12899a39..17c58918de 100644\n--- a/util/cacheflush.c\n+++ b/util/cacheflush.c\n@@ -229,6 +229,10 @@ static void __attribute__((constructor)) init_cache_info(void)\n \n /* Caches are coherent and do not require flushing; symbol inline. */\n \n+#elif defined(EMSCRIPTEN)\n+\n+/* Wasm doesn't have executable region of memory. */\n+\n #elif defined(__aarch64__) && !defined(CONFIG_WIN32)\n /*\n * For Windows, we use generic implementation of flush_idcache_range, that\n","prefixes":["v2","11/20"]}