Re: [patch] tls-2.5.31-C3

Ingo Molnar
2002-08-12T08:04:47Z

On Mon, 12 Aug 2002, Stephen Rothwell wrote:

> > - .quad 0x0040920000000000 /* 0x40 APM set up for bad BIOS's */
> > - .quad 0x00409a0000000000 /* 0x48 APM CS code */
> > - .quad 0x00009a0000000000 /* 0x50 APM CS 16 code (16 bit) */
> > - .quad 0x0040920000000000 /* 0x58 APM DS data */
> > + .quad 0x0040920000000000 /* 0x80 APM set up for bad BIOS's */
> > + .quad 0x00409a0000000000 /* 0x88 APM CS code */
> > + .quad 0x00009a0000000000 /* 0x90 APM CS 16 code (16 bit) */
> > + .quad 0x0040920000000000 /* 0x98 APM DS data */
>
> I just lost 0x40 which needs to be exactly 0x40 if it is do its job
> (i.e. cope with brain dead BIOS writers using 0x40 as a segment offset
> in protected mode ...

you can save/restore 0x40 in kernel-space if you need to no problem.

> The idea is that segment 0x40 maps from physical address 0x400 to the
> end of the first physical page. As a real mode program would (more or
> less) expect it to.

so you are using the kernel's GDT in real mode as well?

Ingo