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Executing PXE ROM without BIOS setting

Posted: Sat Apr 04, 2015 6:36 am
by onlyonemac
Hi,

I suppose that this isn't really an operating system development question but nevertheless I'm sure that the people here are the most likely to be able to help me.

Basically, would it be feasible to somehow execute the PXE ROM for network booting without having to enable it in the computer's BIOS? More specifically, could one write a boot sector for a floppy disk and/or a GRUB payload that could trigger the ROM?

Obviously one would have to somehow determine the correct address in memory where the ROM is located, and in the case of a GRUB payload one would also have to return the CPU to real mode, but would it even work? Or is the correct operation of the ROM dependent on it being enabled in the BIOS?

I ask this because it would be useful to me to have a floppy disk and GRUB payload that would allow me to network boot almost any computer without having to fiddle with BIOS settings.

Thanks,

onlyonemac

Re: Executing PXE ROM without BIOS setting

Posted: Sat Apr 04, 2015 8:17 am
by iansjack

Re: Executing PXE ROM without BIOS setting

Posted: Sat Apr 04, 2015 10:04 am
by onlyonemac
Thanks. I gather that that is not a loader for the network card's ROM but rather a bootloader which is itself the PXE loader, but loaded from disk rather than stored in ROM?

I will look into that - it might well fit my needs.

Re: Executing PXE ROM without BIOS setting

Posted: Sat Apr 04, 2015 9:11 pm
by darkinsanity
onlyonemac wrote:Thanks. I gather that that is not a loader for the network card's ROM but rather a bootloader which is itself the PXE loader, but loaded from disk rather than stored in ROM?
That, and much more. I remember using iPXE (iPXE is the continuation of gPXE) to boot my own OS from an http-server, however, I had problems using iPXE's multiboot support and ended up loading a full GRUB-based iso back then.