Re: [Xen-devel] [PATCH] xen: arm: arm64: Adding VFP save/restore support.

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Thu, Feb 6, 2014 at 1:11 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Thu, 2014-02-06 at 13:08 +0000, Julien Grall wrote:
>>
>> On 06/02/14 12:57, Ian Campbell wrote:
>> > On Thu, 2014-02-06 at 12:44 +0000, Julien Grall wrote:
>> >>> +                 :: "r" ((char *)(&v->arch.vfp.fpregs)): "memory");
>> >>
>> >> I remember we had a discussion when I have implemented vfp context
>> >> switch for arm32 for the memory constraints
>> >> (http://lists.xen.org/archives/html/xen-devel/2013-06/msg00110.html).
>> >>
>> >> I think you should use "=Q" also here to avoid cloberring the whole 
>> >> memory.
>> >
>> > Yes, I forgot to say: I think getting something in now is the priority,
>> > which is why I committed it, but this should be tightened up, probably
>> > for 4.5 unless the difference is benchmarkable.
>>
>> The fix is very simple (a matter of 2 lines changes). I would prefer to
>> delay this patch for a couple of days and having a correct
>> implementation from the beginning, so we will not forgot to change the
>> code for Xen 4.5.
>
> And I would rather close this rather large hole right now and not wait
> for two more days when we are looking at doing what might be the final
> rc soon.
>
> I had already applied before you said anything, so the point is moot.

But just for future reference: Be on your guard against the "hurry and
get in" mentality; it's likely to be counterproductive.  I'd rather
have *more* care taken with the patches at this point than normally.
If that means making a case to delay the release, that's what it will
take.  This would obviously have been a complete blocker -- there's no
way we could in good release without FPU support for guests. :-)

 -George

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