[syslinux] Laptop+SDMMC+Extlinux+Memdisk+Floppy images=headaches

[Cristian Savu]

Hello syslinuxers

I'm stuck with a scientific problem which gives me headaches:

I have a laptop (Gateway MX3410) which has a SD memory card reader.
Recently an interesting thought crossed my mind: why don't I setup
a 2GB SD card as a harddrive and put some rescue tools on it.
So I dug on the net and I came across the idea of using memdisk
to boot floppy images without the need of a floppy drive.
All references I found were about using ISOLINUX with MEMDISK.
But personally I prefer EXTLINUX since it has more flexibility,
given that it can use ext2 fs.

So I installed an MBR on the SD card, then I installed an MBR loader
with lilo (lilo -M /dev/sda). Then I used fdisk to create a partition
and to make it active (primary partition). I then formatted the
partition with mke2fs and ran extlinux to make it bootable.
I copied on it a few floppy images (i.e. a sample dos boot disk,
the bootitng floppy install disk, a win98 boot disk) and added the
extlinux.conf file with the required sections like:

label bootit
kernel memdisk
append initrd=bootit.img

label boot98
kernel memdisk
append initrd=boot98.img

label freedos
kernel memdisk
append initrd=freedos.img

and I thought I would go on and try to see what happens...

Well, pretty much nothing, and I really don't know what
the problem is because all the floppy images seem to
start booting a little, but then the system hangs.
For instance, if I try to boot the MSDOS floppy,
I get the message "Starting MS-DOS" and then the system
just hangs.

Actually, the full message is like this:

some 12-13 lines like:

e820: 00000000fff800000 0000000000000080000 2

then:

Ramdisk at 0x1bda8000, length 0x00168000
command line: initrd=images/boot_flp.img floppy=0 BOOT_IMAGE=memdisk
Disk is floppy 0, 1440 K, C/H/S = 80/2/18
Total size needed = 2008 bytes, allocating 2K
Old dos memory at 0x9dc00 (map says 0x9dc00), loading at 0x9d400
1588: 0xffff  15E801: 0x3c00 0x1ada
INT 13 08: Success, count = 0, BPT = 0000:0000
old: int13 = e8a87ab8  int15 = f000f859
new: int13 = 9d400008  int15 = 92400290
Loading boot sector... booting...
Starting MS-DOS...


and that's all folks, it never goes any further than this...

Another example, the bootit floppy image also starts booting
but it stops on a black screen with the mouse cursor on it.
Interesting, the cursor can be moved with the touchpad, so
something IS working, but not all the way to the end.

For conformance I will mention that all images were made with
 dd if=/dev/fd0 of=/path/to/image.img
and they are valid because I copied them back to floppies and they
booted fine from a FDD.
I will also mention that the SD card is used in BIOS as a USB HDD
and its boot order is before the IDE HDD.
Also, I successfully managed to actually install bootit on the
SD card just as on any HDD, I also made bootable partitions with
DOS and Knoppix and they worked very fine, only this combination
of extlinux and memdisk and bootable floppy images does not work.
I also tried a FAT16 partition and isolinux and memdisk and the same
floppy images, the result is the same, system hangs at boot.

If someone could give me an advice or an indication, point out
some mistake I might have made or simply make some comments,
I would very much appreciate it.

Thanks,

Chris


 
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