[syslinux] PXElinux & memdisk

H. Peter Anvin hpa at zytor.com
Tue Jun 1 20:26:25 PDT 2004

Rob Keeling wrote:
> I am trying to acheve pxe booting of a image of barts boot disk (www.nu2.nu).
> I have managed to get LTSP booting via pxelinux, so I know my dhcp/tftp servers are ok.
> However when I try to boot memdisk with either a stock suselinux boot image file (taken from 
> SuSE 9.1) or my dos disk (created by dd if=/dev/fd0 of=/imagefile) 
> I get output like
> MEMDISK 2.08 
> command line : BOOT_IMAGE=memdisk initrd=sussboot.img
> Disk is floppy, 1440 K, C/H/S = 80/2/18
> Total size needed 1359 bytes, allocating 2K
> Old dos memory at 0xa0c00 (map says 0xa0c00), loading at 0xa0400
> 1588: 0x0000 15e801: 0x0000 0x0000
> INT 13 08 : Success, count = 1, BPT =f000:8487
> old: int13 = f000ec59 int15 = f000f859
> new: int13 = a0400008 int15 = a0400272
> Loading boot sector...
> And hangs at this point.
> Any ideas what I may be doing wrong?

Yes, it's pretty clear what's wrong: "Old dos memory at 0xa0c00".  This 
means your PXE stack has freed up more memory than it took (since 
0xa0000 is the beginning of the VGA region!)

The first thing I'd try is to upgrade your PXE boot rom if you can.  If 
not, I would boot with the "keeppxe" option to keep pxelinux from 
freeing memory.


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