[syslinux] MEMDISK issue with OptiPlex GX280,620

[Shao Miller]

On 1/25/2011 13:36, Jason Vasquez wrote:
> Gladly yes to test, thank you.
>
> System used: OptiPlex GX280, BIOS A08. Results below.
>
> command line: initrd=images/misc/c.img BOOT_IMAGE=memdisk_memdskprobedbg
> Disk is hd0, 10404 K, C/H/S = 306/4/17 (MBR/MBR), EDD on, rw
> Using safe INT 15h access to high memory
> Code 1744, meminfo 276, cmdline 66, stack 512
> Total size needed = 2598 bytes, allocating 3K
> Old dos memory at 0x9fc00 (map says 0xa0000), loading at 0x9f000
> 1588: 0xffff  15E801: 0x3c00 0x7dc3
> INT 13 08: Success, count = 1, BPT = 0000:0000
> INT 13 DL80:
>   AH08: CF1 BL00 DL01
>   AH15: CF1 AH03
>   AH41: CF1 BXaa55 AH30 DH00
> BDA drive 80? 1, total count: 1
> Press a key to continue...

Unfortunately, I had CF's display inverted.  Each of those was really a 
'0' instead of a '1'.  That means "success" for all three.

> INT 13 DL81:
>   AH08: CF0 BL00 DL00
>   AH15: CF1 AH00
>   AH41: CF0 BX55aa AH01 DH00
> BDA drive 81? 0, total count: 1
> Press a key to continue...
> INT 13 DL82:
>   AH08: CF0 BL00 DL00
>   AH15: CF1 AH00
>   AH41: CF0 BX55aa AH01 DH00
> BDA drive 82? 0, total count: 1
> Press a key to continue...
> .
> .
> .
> INT 13 DLff:
>   AH08: CF0 BL00 DL00
>   AH15: CF1 AH00
>   AH41: CF0 BX55aa AH01 DH00
> BDA drive ff? 0, total count: 1
> Press a key to continue...
> We lost the last drive in our class of drives.
> Drive probing gives drive shift limit: 0x01
> old: int13 = f0005c6f int15 = f000f859 int1e = f000efc7
> new: int13 = 9f00000a int15 = 9f0003ba int1e = f000efc7
> Loading boot sector... press any key to boot...

The same thing with these.  For the cases > drive 0x80, AH == 0x08 
returns CF == 1 (error), AH == 0x15 returns CF == 0 ("success"), AH == 
0x41 returns CF == 1 (error).  But anyway, your report is still useful.  
It's the bogus AH == 0x15 "success" case that's hurting these models.  I 
will address that and submit another patch.

Thanks for testing.

- Shao Miller