Re: [PATCH v1 2/8] x86/entry/clearregs: Add infrastructure to clear registers

[Andi Kleen]

> > +   .macro CLEAR_ALL_REGS
> > +   CLEAR_R8_TO_R15
> > +   xorl %eax, %eax
> > +   xorl %ebx, %ebx
> 
> How come you use xorl vs xorq?

64bit always zero extends 32->64, and xorl is one byte
shorter because it doesn't need a REX prefix.

-Andi