[syslinux] Returning to syslinux bootloader
H. Peter Anvin
hpa at zytor.com
Thu Apr 16 11:01:05 PDT 2009
Michael Brown wrote:
>
> FWIW, I have experimented with returning to the gPXE bootloader from an MS-DOS
> instance booted via iSCSI. gPXE captures the INT18/INT19 vectors so that it
> can continue cleanly in the case of a failed iSCSI boot. It is possible to
> abuse this in DOS by writing a reboot.com executable that just calls INT19.
> It does kind of work, but it's not hugely reliable, because DOS will have
> edited the interrupt vector table, etc. and so the machine is left in a
> pretty unsafe state for booting a subsequent OS without a reset.
>
If it was only the IRQ table it wouldn't be so bad -- it's only a
kilobyte to save and restore, after all. However, MS-DOS screws with
BIOS state all over the place, in weird ways.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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