Re: [Qemu-devel] [PATCH v3 03/15] exec-all.h: revert tb_page_addr_t to target_ulong

[Paolo Bonzini <pbonzini@redhat.com>]

On 30/09/2016 23:30, Alex Bennée wrote:
> Commit b480d9b74 converted tb_page_addr_t to abi_ulong which while the
> right size imposes additional alignment restrictions on the type. This
> gets in the way of using atomic accesses on certain guest platforms
> which allow finer alignments. As tb_page_addr_t isn't actually visible
> to the guest we can revert the change.
> 
> This is potentially less efficient for ILP32 style guests but it is the
> simpler change to make.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>  include/exec/exec-all.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 336a57c..c3596a6 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -30,7 +30,7 @@
>     addresses in userspace mode.  Define tb_page_addr_t to be an appropriate
>     type.  */
>  #if defined(CONFIG_USER_ONLY)
> -typedef abi_ulong tb_page_addr_t;
> +typedef target_ulong tb_page_addr_t;
>  #else
>  typedef ram_addr_t tb_page_addr_t;
>  #endif
> 

I think target_ulong is in general not accessible atomically, because we
still haven't dropped 64-on-32 support.

Paolo