Re: [Xen-devel] [PATCH v4 3/4] x86: fix indirect thunk usage of CONFIG_INDIRECT_THUNK

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.02.18 at 13:42, <roger.pau@xxxxxxxxxx> wrote:
> On Tue, Feb 20, 2018 at 05:32:17AM -0700, Jan Beulich wrote:
>> >>> On 20.02.18 at 12:22, <roger.pau@xxxxxxxxxx> wrote:
>> > On Tue, Feb 20, 2018 at 04:13:42AM -0700, Jan Beulich wrote:
>> >> >>> On 20.02.18 at 12:01, <roger.pau@xxxxxxxxxx> wrote:
>> >> > --- a/xen/include/asm-x86/asm_defns.h
>> >> > +++ b/xen/include/asm-x86/asm_defns.h
>> >> > @@ -15,6 +15,9 @@
>> >> >  #include <asm/alternative.h>
>> >> > 
>> >> >  #ifdef __ASSEMBLY__
>> >> > +#ifndef CONFIG_INDIRECT_THUNK
>> >> > +.equ CONFIG_INDIRECT_THUNK, 0
>> >> > +#endif
>> >> >  # include <asm/indirect_thunk_asm.h>
>> >> >  #else
>> >> >  asm ( "\t.equ CONFIG_INDIRECT_THUNK, "
>> >> > 
>> >> > It's fairly similar to my first approach, but at least "#ifdef
>> >> > CONFIG_INDIRECT_THUNK" will still work as expected after this fix.
>> >> 
>> >> I've used something similar in backports to old versions, so I
>> >> wonder whether what you quote above is right: Assembly files
>> >> don't get handed to clang anyway iirc, so the change would
>> >> seem to be needed in the #else part of the conditional.
>> > 
>> > Assembly files do get handed to clang, from xen/Rules.mk:
>> > 
>> > %.o: %.S Makefile
>> >    $(CC) $(AFLAGS) -c $< -o $@
>> > 
>> > Xen doesn't call as directly to compile those, or am I missing
>> > something?
>> 
>> Oh, I was referring to the -mno-integrated-as (or whatever it's
>> called) option. "Handed to clang" wasn't the best way to put it,
>> I agree. But it's clang's integrated assembler which the problem
>> is with.
> 
> Oh, I see. You are right, this is just a preparatory change for patch
> 4, which does enable clang's integrated assembler if the right
> features are present.
> 
> Let me know if you think the above chunk is acceptable.

It is certainly acceptable if it helps; you now apparently agreeing
I'm more confused though by this question. Iirc you don't enable
the integrated assembler for assembly sources, but only for C ones.

Jan


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