RE: [PATCH][v6] Support Intel USER_MSR

["Jiang, Haochen" <haochen.jiang@intel.com>]

> > > +
> > > +// USER_MSR instructions.
> > > +
> > > +urdmsr, 0xf20f38f8, USER_MSR|x64, RegMem|NoSuf|NoRex64,
> { Reg64,
> > > +Reg64 } urdmsr, 0xf2f8/0, USER_MSR|x64,
> > > +Modrm|Vex128|VexMap7|VexW0|NoSuf, { Imm32, Reg64 } uwrmsr,
> > > +0xf30f38f8, USER_MSR|x64, Modrm|NoSuf|NoRex64, { Reg64, Reg64 }
> > > +uwrmsr, 0xf3f8/0, USER_MSR|x64, Modrm|Vex128|VexMap7|VexW0|NoSuf,
> > {
> > > +Reg64, Imm32 }
> >
> > Actually I think the choice of Reg64 here for the operand specifying the MSR
> > index is misleading, even if in line with what the doc presently says in the
> > Opcode / Instruction column. For both insns the description says that only the
> > low 32 bits are used (and the Exceptions section confirms this). Such operands,
> > however, are expressed as Reg32 everywhere else. I'd like to suggest that the
> > spec be adjusted, and I'm heavily inclined to change binutils regardless. Thoughts?

I suppose the reason why it is using Reg64 is because when the other operand is
register, it is rare not to align the register size. I checked SDE and ISE and only
got one case. And this reg size is inherited from that.

However, it might be a point and as Lin said a sync with HW team is needed.

Thx,
Haochen

> 
> Can you give some examples about such operands are expressed as Reg32.  I
> can go ahead and discuss it internally. May need to wait for HJ for final
> confirmation.
> 
> BRs,
> Lin