Re: [PATCH v10 7/9] rust: add crate to expose bindings and interfaces

[Paolo Bonzini <pbonzini@redhat.com>]

On 9/10/24 14:35, Manos Pitsidianakis wrote:
> +unsafe impl GlobalAlloc for QemuAllocator {
> +    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> +        if matches!(Self::DEFAULT_ALIGNMENT_BYTES, Some(default) if default.checked_rem(layout.align()) == Some(0))
> +        {
> +            g_malloc0(layout.size().try_into().unwrap()).cast::<u8>()
> +        } else {
> +            #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)]
> +            {
> +                g_aligned_alloc0(
> +                    layout.size().try_into().unwrap(),
> +                    1,
> +                    (8 * layout.align()).try_into().unwrap(),
> +                )
> +                .cast::<u8>()
> +            }
> +            #[cfg(not(HAVE_GLIB_WITH_ALIGNED_ALLOC))]
> +            {
> +                qemu_memalign(8 * layout.align(), layout.size()).cast::<u8>()
> +            }

The "8 *" is not needed in either case.

To be honest I'd simply drop the allocator code since you have to respin 
(see Junjie's answer).  The DEFAULT_ALIGNMENT_BYTES trick is nice but 
I'm afraid it can be a source of hard-to-debug bugs.

Anyhow, I'll leave the choice to you as long as it's disabled by 
default, and I think with v11 everything should be ready.

Paolo