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Re: CD-ROM booting staus update


From: Robert Millan
Subject: Re: CD-ROM booting staus update
Date: Sun, 1 Jul 2007 13:57:49 +0200
User-agent: Mutt/1.5.13 (2006-08-11)

On Thu, Jun 28, 2007 at 10:04:12AM -0400, Alex Roman wrote:
> On 26/06/07, Alex Roman <address@hidden> wrote:
> >Thought I'd write a little status update on this project.
> 
> All right, I took a look at the Bochs BIOS source code, and they seem
> to be implementing just one Int 13h function that is specified in the
> Eltorito specification: the 4B01h that isolinux needs to boot.
> 
> Next, I started to use Bochs' internal debugger and I noticed that the
> grub_gate_a20 function clobbers %edx which was what was causing me the
> grief, since I was holding the number of bytes to copy from my buffer
> (that I read into from the CD) to 7c00h. So, instead of copying at
> least 2k which is what ISOLINUX expects, it was copying only 224 bytes
> (or something like that, the leftover value in %edx).
> 
> Now that I figured that out, *I managed to get the FreeDOS CD to boot! :)*

Congrats :-)

-- 
Robert Millan

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