Sorry, at the moment I could only suggest to "find" a Windows 7 USB, do a clean install & drivers installation and use this Belkasoft tool according to ultimate VGABIOS extraction writeup - that's if you need it quick. However, if you'll achieve a similar access with Lime, please let us know: it is much better if stuff like this could be done with the opensource software and no Windows hassle.
On Fri, Apr 16, 2021 at 10:52 PM Peter Stuge peter@stuge.se wrote:
Gian Lorenzo Spisso wrote:
Thank you so much for your reply.
Indeed, after a bit of research I've stumbled upon Lime which is a kernel module allowing the dump of the whole memory which I'm doing right now.
Oh good, that's worth a try.
Do you have any pointer on how to locate the bit I'm interested in?
Here's a hex dump of the first 80 bytes of my VGA BIOS:
0000000: 55aa 80e9 a9e3 3030 3030 3030 3030 3030 U.....0000000000 0000010: 3030 b021 e9a1 2059 4000 e00a 3030 4942 00.!.. Y@...00IB 0000020: 4d20 5647 4120 436f 6d70 6174 6962 6c65 M VGA Compatible 0000030: 2042 494f 532e 2003 5b00 6b00 7900 8bc0 BIOS. .[.k.y... 0000040: 5043 4952 8680 a227 0000 1800 0000 0003 PCIR...'........
Bytes 0 and 1, 0x55 and 0xaa, mark the start of the option ROM, and offsets 0x44-48 (0x86 0x80 0xa2 0x27) contain the PCI ID of the graphics hardware that this option ROM is for.
The PCI ID of my graphics hardware is 8086:27a2; note that the two 16-bit numbers are stored little-endian in the image.
Searching for this in e.g. a large file again needs some programming, because the individual bytes (0x55, 0xaa, or the ID bytes) will occur quite frequently.
One option might be to first look for some text strings in the internal VGA option ROM and see if they occur in more locations in the new memory dump, to then search only those regions manually.
I am alsok wondering, should I make sure my gpu is running since its a discrete card for the vbios to be loaded in memory?
Hm, I think that will depend on the particular hardware design of your GPU and of your mainboard. The GPU should not be powered down, because the option ROM is probably only accessible through the GPU.
Finally, if the software approach fails, another method may be to look for the flash chip on the mainboard and read it out with hardware means.
Kind regards
//Peter