Re: [PATCH 00/10] Enable QEMU to run on browsers

[Paolo Bonzini]

On 4/10/25 15:13, Kohei Tokunaga wrote:
> > The biggest problem I'm seeing is we no longer support 64-bit guests on
> > 32-bit hosts, and don't plan to revert that.
>
> Yes, so the sixth patch ("[PATCH 06/10] include/exec: Allow using 64bit
> guest addresses on emscripten") should be considered as a temporary
> workaround, enabled only for Emsripten builds. It will be removed once
> wasm64 gains broader support and is adopted in the Wasm backend.

Maybe there's a way though. Currently we don't support 64-bit guests on 
32-bit hosts, but more precisely we don't support 64-bit guests with 
32-bit host word size.


The wasm TCG backend is able to compile with 64-bit words:

+#define TCG_TARGET_HAS_div_i64          1
+#define TCG_TARGET_HAS_rem_i64          1
etc.

and if x32 was a thing it would as well.  In fact the changes in patch 
6/10 are not a full revert, and the "#ifdef EMSCRIPTEN" could be changed to

#if HOST_LONG_BITS >= TARGET_LONG_BITS
... use uintptr_t
#else
... use uint64_t
#endif

Paolo