Hi Kohei,
On 4/8/25 14:57, Kohei Tokunaga wrote:
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.
This commit adds "--wasm64-memory64" flag to the configure script. This
takes the value to propagate to Emscripten's -sMEMORY64. 1(default) targets
wasm64 engines and 2 targets wasm32 engines with still enabling 64bit
pointers.
[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 | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/configure b/configure
index 7f3893a42f..8573f84e26 100755
--- a/configure
+++ b/configure
@@ -182,6 +182,8 @@ EXTRA_CXXFLAGS=""
EXTRA_OBJCFLAGS=""
EXTRA_LDFLAGS=""
+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 +241,8 @@ for opt do
;;
--without-default-features) default_feature="no"
;;
+ --wasm64-memory64=*) wasm64_memory64="$optarg"
+ ;;
esac
done
@@ -537,7 +541,7 @@ case "$cpu" in
CPU_CFLAGS="-m32"
;;
wasm64)
- CPU_CFLAGS="-m64 -sMEMORY64=1"
+ CPU_CFLAGS="-m64 -sMEMORY64=$wasm64_memory64"
;;
esac
@@ -795,6 +799,8 @@ for opt do
;;
--disable-rust) rust=disabled
;;
+ --wasm64-memory64=*)
+ ;;
# everything else has the same name in configure and meson
--*) meson_option_parse "$opt" "$optarg"
;;
@@ -920,6 +926,8 @@ Advanced options (experts only):
--disable-containers don't use containers for cross-building
--container-engine=TYPE which container engine to use [$container_engine]
--gdb=GDB-path gdb to use for gdbstub tests [$gdb_bin]
+ --wasm64-memory64 Used only for wasm64 build. Set -sMEMORY64 of
+ Emscripten to 1(default) or 2 (choices: 1/2)
I wouldn't expose "1" or "2" to the users. Instead, keep 1 as internal
default, and provide the --wasm64-32bit-address-limit option which sets
internal value to 2. Configure help could be:
--wasm64-32bit-address-limit Restrict wasm64 address space to
32-bit (default is to use the whole
64-bit range).
WDYT?
