Currently there are some engines that don't support wasm64 (e.g. unsupported on Safari[1]). To mitigate this issue, the configure script allows the user to use Emscripten's compatibility feature, "-sMEMORY64=2" flag[2].
Emscripten's "-sMEMORY64=2" flag still enables 64bit pointers in C code. But this flag lowers the output binary into wasm32, with limiting the maximum memory size to 4GB. So QEMU can run on wasm32 engines. [1] https://webassembly.org/features/ [2] https://emscripten.org/docs/tools_reference/settings_reference.html#memory64 Signed-off-by: Kohei Tokunaga <ktokunaga.m...@gmail.com> --- configure | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) V2: - Changed --wasm64-memory64 flag to --wasm64-32bit-address-limit to avoid exposing the -sMEMORY64 value directly to the users. This can be considered as a significant change from the previous version of this patch so the Reviewed-by tag has been removed. - Added a link to the Emscripten documentation about -sMEMORY64 in the configure script. diff --git a/configure b/configure index 7f3893a42f..0587577da9 100755 --- a/configure +++ b/configure @@ -182,6 +182,10 @@ EXTRA_CXXFLAGS="" EXTRA_OBJCFLAGS="" EXTRA_LDFLAGS="" +# The value is propagated to Emscripten's "-sMEMORY64" flag. +# https://emscripten.org/docs/tools_reference/settings_reference.html#memory64 +wasm64_memory64=1 + # Default value for a variable defining feature "foo". # * foo="no" feature will only be used if --enable-foo arg is given # * foo="" feature will be searched for, and if found, will be used @@ -239,6 +243,8 @@ for opt do ;; --without-default-features) default_feature="no" ;; + --wasm64-32bit-address-limit) wasm64_memory64="2" + ;; esac done @@ -537,7 +543,7 @@ case "$cpu" in CPU_CFLAGS="-m32" ;; wasm64) - CPU_CFLAGS="-m64 -sMEMORY64=1" + CPU_CFLAGS="-m64 -sMEMORY64=$wasm64_memory64" ;; esac @@ -795,6 +801,8 @@ for opt do ;; --disable-rust) rust=disabled ;; + --wasm64-32bit-address-limit) + ;; # everything else has the same name in configure and meson --*) meson_option_parse "$opt" "$optarg" ;; @@ -920,6 +928,8 @@ Advanced options (experts only): --disable-containers don't use containers for cross-building --container-engine=TYPE which container engine to use [$container_engine] --gdb=GDB-path gdb to use for gdbstub tests [$gdb_bin] + --wasm64-32bit-address-limit Restrict wasm64 address space to 32-bit (default + is to use the whole 64-bit range). EOF meson_options_help cat << EOF -- 2.43.0
