[SeaBIOS] insn prefixes?
kevin at koconnor.net
Sat Oct 2 16:32:08 CEST 2010
On Sat, Oct 02, 2010 at 11:39:06AM +0200, Avi Kivity wrote:
> On 09/30/2010 05:51 AM, Kevin O'Connor wrote:
> >On Wed, Sep 29, 2010 at 08:19:33AM -0700, H. Peter Anvin wrote:
> >> Yeah... big real mode is rather expensive in terms of the 66 and 67
> >> prefixes you end up littering the code with just to be in the mode you
> >> actually want. Better then to load a GDT, flip CR0.PE, and go to a
> >> 32-bit code segment anyway.
> >That brings up an interesting question. Do you know if instruction
> >prefixes result in slower cpu execution?
> Is there really a performance problem in seabios?
No. I was asking only out of curiosity. Even if prefixes slow 16bit
mode, a normal SeaBIOS boot runs very little 16bit code.
More information about the SeaBIOS