[coreboot] [RFC] port bochs-bios to gcc
kevin at koconnor.net
Tue Feb 26 02:09:43 CET 2008
On Mon, Feb 25, 2008 at 06:25:14PM +0900, Jun Koi wrote:
> On 2/25/08, Jun Koi <junkoi2004 at gmail.com> wrote:
> > Hmm somehow I missed it: that is the _start in romlayout.S. But then
> > the question is: why the _start code jump back to itself at start
> > up???
> Ah, now I see what happens. The -fwhole-program --combine option
> really confuses me!
The code is entered in 16bit mode at ffff:fff0 (romlayout.S) - it then
jumps to "post16" in romlayout.S. The code there transitions the CPU
to 32bit mode and jumps to _start in post.c. After we initilize
everything, the cpu is transitioned back to 16bit mode and an "int
0x19" is executed to start the standard boot process.
The _start in romlayout.S is confusing - I put it there to silence a
linker warning. I'll clean that up.
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