Re: [Xen-devel] [PATCH 1/7] x86/alt: Drop unused alternative infrastructure

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.02.18 at 15:41, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 13/02/18 14:22, Jan Beulich wrote:
>>>>> On 12.02.18 at 12:23, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> @@ -118,26 +113,6 @@ extern void alternative_instructions(void);
>>>                                newinstr2, feature2)                 \
>>>                  : output : input)
>>>  
>>> -/*
>>> - * This is similar to alternative_io. But it has three features and
>>> - * respective instructions.
>>> - *
>>> - * If CPU has feature3, newinstr3 is used.
>>> - * Otherwise, if CPU has feature2, newinstr2 is used.
>>> - * Otherwise, if CPU has feature1, newinstr1 is used.
>>> - * Otherwise, oldinstr is used.
>>> - */
>>> -#define alternative_io_3(oldinstr, newinstr1, feature1, newinstr2, \
>>> -                    feature2, newinstr3, feature3, output,         \
>>> -                    input...)                                      \
>>> -   asm volatile(ALTERNATIVE_3(oldinstr, newinstr1, feature1,       \
>>> -                              newinstr2, feature2, newinstr3,      \
>>> -                              feature3)                            \
>>> -                : output : input)
>>> -
>>> -/* Use this macro(s) if you need more than one output parameter. */
>>> -#define ASM_OUTPUT2(a...) a
>> ... I'm having patches to post which use both of these, so I'd
>> very much prefer them to not go away. It is simply a lack of time
>> which resulted in me not having posted that series already.
> 
> In which case I'll need to review that patch before commenting on this
> one (i.e. whether it actually needs to be an alternative_3, or whether
> there is a shorter way to do it).

I've checked again - if the NOP replacement of the unused space in
the original instruction was taken care of (which I understand later
patches in this series arrange for), I would need only the 2-variants
form. I'll need ASM_OUTPUT2() in any case, though.

Jan


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