[LinuxBIOS] Bios "Bible"?
stuge-linuxbios at cdy.org
Wed Mar 30 01:25:42 CEST 2005
On Tue, Mar 29, 2005 at 09:29:06PM -0800, Justin Walsh wrote:
> Or what is the definitive Blue Book on:
> 1. Bios in General?
> 3. Bios in particular?
I'm not sure there is one. Traditionally BIOS code seem to have been
a secret well-kept by mainboard/BIOS companies.
> 3. How does one switch a 686 or 786 from native into real mode?
> i.e. 286 emulation?
x86 CPUs start up in a backwards-compatible 8086 real mode. Protected
mode is entered by setting bit 0 in the cr0 register, but first some
descriptor tables need to be set up. Switching back and forth
basically is a matter of flipping the PE bit.
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