Re: [RFC v2-fix-v1 1/1] x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions

[Andi Kleen]

On 5/19/2021 1:09 PM, Sean Christopherson wrote:
> On Wed, May 19, 2021, Kuppuswamy, Sathyanarayanan wrote:
> > On 5/19/21 8:31 AM, Dave Hansen wrote:
> > > Was this "older compiler" argument really the reason?
> > It is a speculation. I haven't tried to reproduce it with old compiler. So
> > I have removed that point.
> It's not "older" compilers.  gcc does not support R8-R15 as input/output
> constraints,

Yes that's true, but they can be in clobbers. So it usually just needs a 
mov from the input arguments for output, or a mov to the output 
arguments for output.