Re: [GIT PULL] x86 setup: correct booting on 486 (revised)

Linus Torvalds
2007-11-05T18:38:10Z

On Mon, 5 Nov 2007, H. Peter Anvin wrote:
>
> Well, the 32-bit code needs to set up its own stack, and only it knows where
> it wants its stack; we don't guarantee that the stack is valid when we enter
> the 32-bit code and we're entering with both INT and NMI disabled (requiring a
> stack would probably break all existing users of the 32-bit entrypoint.)

I agree. But it would be nice if some basic instructions still worked: as
is, you cannot even do things like reloading %eflags, because the only way
to do that requires a stack.

> However, that being said, doing so is trivial, and it might help some
> debugging hack; anything that makes debugging easier is a Good Thing[TM].

Yeah. Even if it was just re-using the boot-time stack area temporarily,
just to give code the choice to use a common set of instructions.

Linus