[syslinux] [BUG] boot failure since syslinux-3.00

[Sebastian Herbszt]

H. Peter Anvin wrote:
> I have no idea.  The BIOS you pointed me to unambiguously claims EDD is 
> supported, it clearly also has code to use EDD, and yet it fails when 
> one attempts to use it.

I have traced the bios a bit and got to where it does the read from port 0x1f0:
000fa6fa: (                    ): cli                       ; fa
000fa6fb: (                    ): rep insw word ptr es:[di], dx ; f36d
000fa6fd: (                    ): sti                       ; fb

It does hit this twice. First time via int13h, ah=02h from the bios to read to 0x7c00
and the second time from extlinux via int13h, ah=42h to read to 0x7e00. The first hit
does obviously succeed since extlinux is loaded and memory at 0x7c00 gets populated
but the correct data. When it hits 0xfa6fa the second time the memory at 0x7e00 doesn't
seem to get populated with any data (it stays filled with zeros). Didn't figure out why (yet).

- Sebastian