Re: [Xen-devel] [PATCH] xen/arm64: disable alignment check

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 28/04/14 10:48, Ian Campbell wrote:
> On Sun, 2014-04-27 at 10:10 +0100, Vladimir Murzin wrote:
>> Alignment check is enabled by default at Xen boot.
> 
> This has already been disabled in the development branch via:
> commit 58bbe7d71239db508c30099bf7b6db7c458f3336
> Author: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Date:   Wed Mar 26 13:38:45 2014 +0000
> 
>     xen: arm64: disable alignment traps
>     
>     The mem* primitives which I am about to import from Linux in a subsequent
>     patch rely on the hardware handling misalignment.
>     
>     The benefits of an optimised memcpy etc outweigh the downsides.
>     
>     Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>     Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
>     Acked-by: Tim Deegan <tim@xxxxxxx>
> 
> I will consider this for backport, but first I'd like to consider
> whether we shouldn't fix the hypervisor side evtchn FIFO code along the
> same lines as the kernel side. David, any thoughts?

I believe Jan suggested making Xen's bitops handle 32-bit alignment or
adding a new set of 32-bit bitops.

David

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