freebios2 mod to reset code.
Steve Gehlbach
steve at nexpath.com
Wed Jul 23 11:47:00 CEST 2003
ron minnich wrote:
> make reset a rel jump to 0xfffffff0 - (sizeof entry16). Then put entry 16
> right before 0xfffffff0. Entry16 code turns on 32-bit mode and then jumps
> to the real start of the linuxbios image -- which can now be anywhere in
> the flash image. I could use this now, as could others.
>
I suggested this last year, with the comment that this is a more
traditional way that embedded systems start up. Your objections at the
time were that it would cause trouble with some motherboards, but I
don't remember the specifics. I was wanting to do this since it is
clear that we will be getting 2 Mbyte LPC soon and be able to boot
Linux easily out of flash (as I think you have already done).
One caveat I discovered, I could never get Linux to boot with a gdt
located higher than 1M. So even if you put a linux compatible gdt high,
it has to be moved to ram < 1M or linux hangs on boot. Never figured
out why (true for 2.4 anyway).
Also, on the dynamic/static trees, one thing to consider in the mix is
the serial ATA. I think it is an external chip now but will be subsumed
into the bridge chips at some point. Not sure how a chip function
moving around like this affects the software design.
-Steve
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