(UEFI) Dell XPS 15z L511z modded BIOS - and HOWTO

[jkbuha]

from the UEFI IFR specification - it's a UINT64 variable after the suppress opcode (0A 82 45 8A). So 00 really is 00 00 00 00 00 00 00 00, and because it's little-endian we modify only the first byte to make it a 01. In your case it may be that 0A 82 45 0A is the opcode (yours may have a different sequence) which is why I'm interested to see if you have that byte sequence: 0A 82 45 0A 00

[Mohamed Khairy]

from the UEFI IFR specification - it's a UINT64 variable after the suppress opcode (0A 82 45 8A). So 00 really is 00 00 00 00 00 00 00 00, and because it's little-endian we modify only the first byte to make it a 01. In your case it may be that 0A 82 45 0A is the opcode (yours may have a different sequence) which is why I'm interested to see if you have that byte sequence: 0A 82 45 0A 00

see here is assembly by Florin9doi if you want to see it

http://www.sendspace.com/file/voutq9

[jkbuha]

@kasar - I have suppress code occurrences in two more modules:
166CD554-8AAE-4617-8FDD-A2E3A5AFD89E_1_1056.ROM: 2
4A538818-5AE0-4EB2-B2EB-488B23657022_0_4.ROM: 15

[TimeWalker]

[censored], Trusted Platform Module would be cool to have .. if it's anywhere close to what Latitude D630 used to have.
Computrace .. meh, not so much .. but useful if you have a kid enable it by accident

Please report how this goes.

[kasar]

@jkbuha

I dont have those files.

those numbers differs from bios to bios I think.

however, the efi file name is written inside one of the 1 kb file with almost the same name the others.

for example SystemVgaDxe.efi

in the other hand, modifing other modules, specially boot modules , shouldnt that be dangerous?

I mean if some critical module fail to load due a fail string replacement it can brick the machine, it wasnt important at the setup module cause it just fail while you enter at the setup module, you can allways flash the bios back to recover it.
however not sure about others.

with the options tweaking, the only way to brick the machine is by changing bios options via menu, however you can allways do a clear cmos by removing the cmos battery to clear the settings.

[Mohamed Khairy]

can any one share setup.asm (untouched) of his unlocked bios I want to compare

edit

don't worry about that I extracted it from linked bios on first post

[TimeWalker]

A user by the name dexz has confirmed UEFI working for Windows 7 UEFI installations.
The result is that Windows Boot Manager sets itself as a boot option through UEFI Shell's bcfg:


Even though we don't technically have access to our native shell yet we can use the one, say from Intel's EDK.
You have to get the Shell.efi module, rename it to bootx64.efi and place onto a FAT32 formatted USB stick creating a folder /EFI and copying bootx64.efi to this folder.
When you boot from that stick it will load up shell giving you all sorts of access .. like for example adding CLOVERX64.efi as an additional boot option (like Windows Boot Manager on the screenshot above).

[musicthebee]

Can I use Bios1_A11.WPH file from the BiosA11.zip file attached to the first post to flash?

This is for XPS 15Z (L511z).

Thanks
MK

[TimeWalker]

Like jkbuha said earlier, there are 2 occurrences of IFR_SUPRESS in SystemSetupSecurityDxe.efi
For Vostro 3450 bios GUID = 166CD554-8AAE-4617-8FDD-A2E3A5AFD89E_1_1079
EFI_IFR_SUPRESS: 0A 82 45 8A (00) 00 00 00 00 00 00 00 45 0A
Address of 1st occurrence: 88F9
Address of 2nd occurrence: 897F
If these are in fact IFR SUPRESS sequences then they must be related to TPM unlocking as there are text string regarding TPM found in the module.

The file that is 7.5Mb in size also has few occurrences but I guess it's really a bad idea to tamper with this as it appears to be the base of the entire fw.

Also I have found an interesting string in SystemBootManagerDxe.efi which says: "F11 - Internal Shell"

[kasar]

Like jkbuha said earlier, there are 2 occurrences of IFR_SUPRESS in SystemSetupSecurityDxe.efi
For Vostro 3450 bios GUID = 166CD554-8AAE-4617-8FDD-A2E3A5AFD89E_1_1079
EFI_IFR_SUPRESS: 0A 82 45 8A (00) 00 00 00 00 00 00 00 45 0A
Address of 1st occurrence: 88F9
Address of 2nd occurrence: 897F
If these are in fact IFR SUPRESS sequences then they must be related to TPM unlocking as there are text string regarding TPM found in the module.

The file that is 7.5Mb in size also has few occurrences but I guess it's really a bad idea to tamper with this as it appears to be the base of the entire fw.

Also I have found an interesting string in SystemBootManagerDxe.efi which says: "F11 - Internal Shell"

oh, thanks for the info TimeWalker

anyway, like you said, it seems dangerous to mess with the boot secuence modules.

because I supose a small mistake can kill the entire boot secuence, resulting in a brick.

I think our priority now should be get the bios recovery function working.

I will save us from getting another motherboard if we broke something in bios, also with the recovery working we can also do more agresive tests ^^