[syslinux] MEMDISK issue with OptiPlex GX280,620

[Shao Miller]

On 1/25/2011 22:07, Gene Cumm wrote:
> One part, yes.  I've got an E6400 with A14 that still "lost the last 
> drive".
>
> Loading from a USB flash drive (my build at 558087b):
>
> INT 13 08: Success, count = 2, BPT = 0000:0000
> INT 13 DL80:
>  AH08: CF0 BL00 DL02
>  AH15: CF0 AH03
>  AH41: CF0 BXaa55 AH21 DH00
> BDA drive 80? 1, total count: 2
> Press a key to continue...
> INT 13 DL81:
>  AH08: CF0 BL00 DL02
>  AH15: CF0 AH03
>  AH41: CF0 BXaa55 AH30 DH00
> BDA drive 81? 1, total count: 2
> Press a key to continue...
> INT 13 DL82:
>  AH08: CF0 BL00 DL02
>  AH15: CF0 AH01
>  AH41: CF0 BX55aa AH01 DH00
> BDA drive 82? 0, total count: 2
> Press a key to continue...
>
> The results on DL=83h through FFh are identical to 82h.

D'oh!  I'm assuming you're using the merged version.  That really 
doesn't seem right at all.  Why would their BIOS report CF == 0 
("success"), AH == 01h ("floppy drive type") for DL >= 82h ?

Then there's the matter of AH == 08h and AH == 41h returning CF == 0.

It looks as though they've a "standard response" for AH == 08h, likely 
based on (DL & 80h) ("hard drive class").  I'm not 100% sure how we 
could approach this, as apparently some BIOSes give weird things in 
their DL response.

I guess we could add to AH == 41h to check (BX != 0xAA55).  If 
extensions aren't present, we can discard the relevance of the 
function's "success."

Are you already intended to patch or not?  (Duplication of effort 
avoidance co-ordination. :) )

- Shao Miller