Re: [patch] SMP alternatives

[jmerkey]

On Wed, Nov 23, 2005 at 11:03:15AM -0800, Linus Torvalds wrote:
> 
> 
> On Wed, 23 Nov 2005, Jeff V. Merkey wrote:
> >
> > The lock prefix '0F' is used for a lot of opcodes other than "lock". Go check
> > the instruction set reference.
> 
> No it's not.
> 
> 0F is indeed the two-byte prefix. But lock is F0, and it's unique.
> 
> Sometimes Intel re-uses the prefixes for other things eg "rep nop", but I 
> don't think that has ever happened for the lock prefix. 
> 
> Besides, the instructions look very different internally in the CPU after 
> decoding, and anyway you'd not want to ignore the lock prefix _early_ at 
> decode time anyway (many instructions turn into illegal instructions with 
> a lock prefix, as do reg-reg modrm bytes). So you'd dismiss the lock 
> prefix not at a byte level, but at a minimum just after the decode stage.
> 
> 		Linus

I always get numbers and words transposed.  Thanks for the correction. 

J
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/