On Tue, 20 Aug 2019, Thomas Hellström (VMware) wrote:
> On 8/20/19 1:32 PM, Peter Zijlstra wrote:
> > On Sun, Aug 18, 2019 at 04:33:14PM +0200, Thomas Hellström (VMware) wrote:
> >
> > > +#define VMWARE_HYPERCALL \
> > > + ALTERNATIVE_2(".byte 0xed", \
> > > + ".byte 0x0f, 0x01, 0xc1", X86_FEATURE_VMW_VMCALL, \
> > > + ".byte 0x0f, 0x01, 0xd9", X86_FEATURE_VMW_VMMCALL)
> > For sanity, could we either add comments, or macros for those
> > instrucions?
>
> Hmm. Here I followed and slightly extended what was done in asm/kvm_para.h.
>
> What confuses me a bit is, if it's clarity we're after, why don't people use
>
> #define VMWARE_HYPERCALL \
> ALTERNATIVE_2("inl (%%dx)", \
> "vmcall", X86_FEATURE_VMW_VMCALL, \
> "vmmcall", X86_FEATURE_VMW_VMMCALL)
>
> Seems to build fine here. Is it fear of old assemblers not supporting, for
> example vmmcall
The requirement for binutils is version >= 2.21. If 2.21 supports vmcall and
vmmcall all good.
Thanks,
tglx
