entering protected_start halt

zhu shi song zhushisongzhu at yahoo.com
Fri Aug 20 07:51:00 CEST 2004

I have made one romimage , it can copy linuxbios into
RAM and execute it from there.  That means raminit.inc
init sdram ok.  I have ported the init code in
raminit.inc to ipl.S.  The only difference of them is
that ipl.S init sdram in real mode and raminit.inc
init sdram in protected mode.  After IPL.s
initialization of sdram, IPL.s can copy code from doc
to RAM at 0x8000:0000 and execute some statements. 
That means at least sdram can be read and written.
Should I enter proteced mode before initializing
sdram?  Who has the experience of initializing sdram
correctly in real mode using vt8601?

--- Stefan Reinauer <stepan at openbios.org> wrote:

> * zhu shi song <zhushisongzhu at yahoo.com> [040819
> 15:42]:
> > I'm using QDIA6T MB based on vt8601/vt82c686.  Now
> I
> > can boot it using DOC IPL. I can copy linuxbios
> from
> > DOC to RAM at 0x8000:0. But when linuxbios
> executed
> > "data32  ljmp    $ROM_CODE_SEG,
> $__protected_start"
> > statement.  The MB halted.   help!
> >   zhu
> Seems your RAM is not initialized correctly?! Any
> room for debugging
> output in docipl?
> Stefan

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