Sorry didn't saw the notify.
EXT might be used as resident "extension" of GROUP or ITEM.

O my, I'm so sorry @noInk I've been checking back to see if anyone had found more information but I only just noticed there was a page 2!

They seem to put EXTBIOS.bin under different extensions, from what I can tell all the Intel ones have it as a OEM module and AMD ones are HOLES.



So far every BIOS that I've checked that have Hybrid EFI have had EXTBIOS.bin somewhere in it, generally OEM7 (I've checked 13). I noticed that HOLE modules weren't compressed but whenever I try and extract one I only end up with a 12KB file, not the 460KB I should end up with :/ I vaguely remember something about some CBROM versions having some issues with compression but I'm still not sure if that will get me anywhere.

I actually have a second X58 board at the back of a storage shed, I'm thinking I could start using that for some attempted bios mods and try to switch out the EXTBIOS.bin module with some TianoCore builds, of course I have no idea what I'm doing so it's probably going to be a short learning experience. But from what I've read, the Legacy bios does the start up, then passes everything over control to the Hybrid EFI (which Roderick believes to be a modified version of Tianocore, I'm wondering if it was just put together from some unfinished build since it was rushed out the door) and if that is all Tianocore needs, then it should in theory work? from there I'm hoping to install drivers and a boot manager, since there is a lot more documentation on TianoCore than Hybrid EFI. All 13 EXTBIOS.bin files have been the same size, so it is possible that if it works, it could work on at least the Intel boards with Hybrid EFI.

@ShadowsNight - which BIOS do you need "Holes" from, I'll see if I can extract for you and if so tell you which cbrom I used
Or, you can always grab it via hex possibly too, since it doesn't look to be compressed

This is a necrobump, I do apologize, but I came across this post when I was doing my own tinkering with GA-X58A-UD5 (rev 2.0) and Hybrid EFI. I was just recently made aware that this MOBO is EFI-capable, and currently have rEFInd and Windows 11 (in UEFI mode) up and running.

But, it does come with some quirks. For starters, you cannot (or at least I cannot) boot from an ESP on a USB flash drive. Booting from an ESP on an internal drive works, but it will always pick the first EFI-partition it finds on the drive. It is also missing some drivers that you would typically find on an EFI-system. This can be solved by loading them through rEFInd, though.

@ShadowsNight, did you make any further findings/progress? It would be interesting if one could fix some of the quirks by modding/updating the EFI-part of the BIOS. To make it "fully" EFI-capable.

Was claimed not even an Hybrid EFI bios, only full legacy...: Another legacy NVME request, with a twist!

U can try this, but haven't heard recent reports from it: [Experimental] NVMe Option ROM