Re: [BUG] x86 kenel won't boot under Virtual PC

["H. Peter Anvin" <hpa@zytor.com>]

Linus Torvalds wrote:
> 
> Peter - does gcc actually use NOPL in _32-bit_ code too? It really seems 
> to be a stupid decision to make a binary not run on other CPU's over 
> something as trivial as that. That's something I'd expect out of an Intel 
> compiler just to mess with AMD, not out of gcc.
> 

Yes, it does:

   /* We need to decide which NOP sequence to use for 32bit and
      64bit. When -mtune= is used:

      1. For PROCESSOR_I386, PROCESSOR_I486, PROCESSOR_PENTIUM and
      PROCESSOR_GENERIC32, f32_patt will be used.
      2. For PROCESSOR_PENTIUMPRO, PROCESSOR_PENTIUM4, PROCESSOR_NOCONA,
      PROCESSOR_CORE, PROCESSOR_CORE2, and PROCESSOR_GENERIC64,
      alt_long_patt will be used.
      3. For PROCESSOR_ATHLON, PROCESSOR_K6, PROCESSOR_K8 and
      PROCESSOR_AMDFAM10, alt_short_patt will be used.

      When -mtune= isn't used, alt_long_patt will be used if
      cpu_arch_isa_flags has Cpu686. Otherwise, f32_patt will
      be used.

"alt_long_patt" uses NOPL and its variants.

	-hpa