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

Ján ONDREJ (SAL) ondrejj at salstar.sk
Thu Sep 12 17:51:21 BST 2013


On Thu, Sep 12, 2013 at 05:42:11PM +0100, Matthew Walster wrote:
> 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".

May be he can use "kexec" to load an ipxe.lkrn file as linux kernel.
Then his "tiny linux" will be killed, but ipxe will be started.
Also it's possible in linux to create a custom ipxe.lkrn, where it's
possible to update linked script, which can do what is required.

					SAL


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