[ipxe-devel] ipxe-boot from linux directly possible?

Matthew Walster matthew at walster.org
Thu Sep 12 16:42:11 UTC 2013

On 12 September 2013 12:41, Oliver Rath <rath at mglug.de> wrote:

> is the following scenario possible:

IIRC, no. My knowledge on these things is very rusty (>10 years) but once
you've entered protected mode, you can't re-enter real mode (with certain
provisos introduced with the 80386 chip). What that means is that once
you've said "give me the full capabilities of the system" you can't then
revert to a boot environment without going through a warm reboot. In real
mode, you only have 1MB addressable memory. I believe memdisk etc use some
sort of shim header​​ that allows you to write to extra RAM and then put
the program counter at the boot sequence -- but that's not sitting pretty
in my head. I'm sure someone can fill in the cavernous gaps in my knowledge
-- or just say "what you suggest isn't feasible".


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