Re: [PATCHv2 3/6] xen: generic xadd() for ticket locks

[David Vrabel <david.vrabel@citrix.com>]

On 17/04/15 14:09, Ian Campbell wrote:
> On Fri, 2015-04-17 at 13:34 +0100, David Vrabel wrote:
>>
>> Can you use
>>
>>   git://xenbits.xen.org/people/dvrabel/xen.git ticketlocks-v3

git://xenbits.xen.org/people/dvrabel/xen.git ticketlock-v3

> I tried that and it built and booted just fine on both arm32 and arm64.
> 
> I eyeballed the assembly produced via the use of __sync_fetch_and_add
> (for _spin_lock only) and it is exactly what I would have written in my
> own versions.
> 
> I was using gcc 4.8.3 in both cases. For arm64 I'm pretty sure we don't
> want to consider anything earlier.
> 
> For arm32 I have also tried gcc 4.6.3 (Debian Wheezy's compiler) and it
> built and booted, and eyeballing shows the same asm. I think that's the
> earliest we really need to worry about.
> 
> IOW I'm not going to bother with custom versions of these functions on
> ARM. If you wanted you could drop the #ifndef xadd from
> asm-arm/system.h.
> 
> Perhaps it would be useful to add some of the info from my tests
> reported above, or a reference to this mail, to the commit log?
> 
> in either case you can add:
> 
>         Acked-by: Ian Campbell <ian.campbell@citrix.com>

Thanks, Ian!

David