Re: [PATCH v2] exec: don't use void* in pointer arithmetic in headers

[Philippe Mathieu-Daudé]

Hi Roman,

On 20/6/24 22:16, Roman Kiryanov wrote:
> void* pointer arithmetic is a GCC extentension
> which could not be available in other build
> tools (e.g. C++). This changes removes this
> assumption.
>
> Google-Bug-Id: 331190993
Again [*] I'm trying to figure what this tag is, no hit on
https://issuetracker.google.com/issues?q=id:331190993; is
this useful to commit it in the mainstream repository? So
far it is confusing me.

[*] 
e865d8e3-e768-4b1f-86d3-aeabe8f1d511@linaro.org/">https://lore.kernel.org/qemu-devel/e865d8e3-e768-4b1f-86d3-aeabe8f1d511@linaro.org/
> Change-Id: I5a064853429f627c17a9213910811dea4ced6174
Ditto, not useful.

Per 
4b3d0472-8b06-403a-9ab8-553aa858fb7f@redhat.com/">https://lore.kernel.org/qemu-devel/4b3d0472-8b06-403a-9ab8-553aa858fb7f@redhat.com/
I wonder if this deserves a:
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>

> Signed-off-by: Roman Kiryanov <rkir@google.com>
> ---
> v2: renamed from "use char* for pointer arithmetic"
>      and removed all explicit extra cast with
>      one typedef in memory.h.
>
>   include/exec/memory.h | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index b1713f30b8..b616338f05 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -2795,8 +2795,10 @@ MemTxResult address_space_write_rom(AddressSpace *as, 
> hwaddr addr,
>   #define ARG1_DECL    AddressSpace *as
>   #include "exec/memory_ldst_phys.h.inc"
>   
> +typedef uint8_t *MemoryRegionCachePtr;
> +
What about:

  typedef uint8_t UnstructuredData;

>   struct MemoryRegionCache {
> -    void *ptr;
> +    MemoryRegionCachePtr ptr;
and:

      UnstructuredData *ptr;

?

>       hwaddr xlat;
>       hwaddr len;
>       FlatView *fv;