Re: [PATCH] x86: work around clang IAS bug referencing __force_order

[Thomas Gleixner]

On Thu, Aug 20 2020 at 09:06, Arvind Sankar wrote:
> I don't think that's an issue, or at least, not one where force_order
> helps.
>
> If the source for foo() is not visible to the compiler, the only reason
> force_order prevents the reordering is because foo() might have
> references to it, but equally foo() might have volatile asm, so the
> reordering isn't possible anyway.
>
> If the source is visible, force_order won't prevent any reordering
> except across references to force_order, but the only references are
> from the volatile asm's which already prevent reordering.
>
> I think force_order can only help with buggy compilers, and for those it
> should really have been an input-output operand -- it wouldn't currently
> do anything to prevent cr writes from being reordered.

Fair enough. Care to provide a patch which has the collected wisdom of
this thread in the changelog?

Thanks,

        tglx