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

[kasar]

well, I am not fully sure what you changed with BMP wich I assume it is some intel software to make changes at the video bios, well , any extra information wold be apreciated, but I assume you added extra resolutions and other stuff.


the point of me patching the table it was I remember I had some issues by using newer intel bioses, like having issues with the internal screen baklit and mDP port.

I compared the device table stated by jkbuha, from my original vbios and your new l502x video bios and it had some differences.
thats why I patched it

[Brabbelbla]

BMP is, like you said, an Intel utility to change settings in their binary files (Binary Modification Program). To use it you need the binary (actual VBIOS) file to modify and a BMP script file. First are many ways to come by, second can be found for some VBIOS versions in the 64-bit Intel drivers. As an example of what settings one sees, I attached the exported settings file for the L702X v2158 VBIOS.

My actual work was rather minor. Loaded the stock v2104 VBIOS with the best fitting script file (v2089) in BMP, exported the settings, made four changes to make it compatible with the v2158 script and then applied the settings and saved. There was no need to 'add' higher resolutions, as they actually were already present in stock v2104, but somehow didn't work. Basically all OEM settings have been carried over, and over here brightness controls work just as they did. If you want to have a look yourself, PM me. Kudos for TimeWalker for providing me.

I compared the settings files of my and your patched version, and couldn't find any differences. Strange. Maybe you changed the actual VBIOS code instead of settings?

[kasar]

yeah, I didnt used BMP even a single time.

I just replaced the hex part jkbuha said with a hex editor.

probably it is VBIOS code itself instead settings.

if you hex compare the files, there are definitly some changes at the part jkbuha said.

[Brabbelbla]

@kasar
Yep, there are binary differences. But yeah, without your changes, my backlight and it's controls work just as they should. Unfortunately, I cannot test the mDP port, so I don't know about that. I think it should work left in the way I posted them, but I cannot say for sure. Do as you see fit; yet unlikely, I don't want to cause bricks by being stubborn

BTW, I presume you weren't lucky with flipping 01's and 00's in the setup module?

[jkbuha]

Hey guys - happy weekend!

I'd like to relate an interesting story that happened to me yesterday. Based on DoiX's Clover discussion on insanely's forum I was trying to reanimate my EFI boot via Clover, and for some reason I got a KP on OSX booting (for some reason the latest clover loaded the GeForce kext which then collided with my FakeSMC and DSDT, ie: Nvidia disabled). I mistakenly thought it was due to the ACPI DMI settings in the BIOS, so I tried to change all the DMI settings to disabled, saved and rebooted. Nothing - Black screen at first and laptop then powered off by itself. Hmmm. I unplugged power, replugged and tried again. Same thing. Not good.

This carried on without any joy, and there I was thinking I now had a proper excuse to get the new XPS. Thankfully I remembered the bios recovery cd me+kasar had done, whipped it into the drive, unplugged power, pressed End key and released it 0.5s after plugging the power cable back in. Voila - laptop boots into recovery mode, I nip into the BIOS setup, reset everything to default, save and restart normally. Worked a treat.

So... (i) has this ever happened to anyone here (ii) is this an incorrect BIOS setting, or corrupt nvram seeing as I was playing about with UEFI?

Guess the 15z will be hanging around for a bit longer

Cheers
jkbuha

[TimeWalker]

heh, I guess these machines are just begging to be bricked glad you had the crisis CD handy.

[kasar]

yeah, I cant belive my machine didnt got bricked after all the stuff, even soldering and desoldering chips and messing with the ME region part.

glad I had a whole chip backup and some extra bios chips and programer ^^

[thorbsd]

I'm just wondering if you guys could help me understand a little bit more about UEFI. I've never set up any OS with UEFI and I'm not totally clear on how everything fits together.

My impression for the old BIOS type system is this:
Power on -> BIOS loads -> boot loader on first sector of HD (installed by the OS) -> OS loads

My impression for UEFI type system is this:
Power on -> UEFI loads -> UEFI bootloader (which is already installed from the manufacturer (edk2?)) -> OS install creates an entry in the UEFI bootloader -> OS loads

Then if someone installs something like "Clover EFI" it's just a more feature filled replacement UEFI bootloader than the one that's already installed by the manufacturer? Does the UEFI bootloader reside within memory space present on the UEFI chip itself, or is it located on the hard drive? I was under the impression it was located on the chip itself.

Also, in the case of the XPS 15z, when using the "legacy mode", the computer is still operating off UEFI except it is simply emulating the BIOS environment and you use the MBR based OS installations as usual.

[TimeWalker]

My impression for the old BIOS type system is this:
Power on -> BIOS loads -> boot loader on first sector of HD (installed by the OS) -> OS loads

BIOS > MBR -> PBR > BOOTLOADER > OS

My impression for UEFI type system is this:
Power on -> UEFI loads -> UEFI bootloader (which is already installed from the manufacturer (edk2?)) -> OS install creates an entry in the UEFI bootloader -> OS loads

UEFI > BOOTLOADER.EFI > OS

Then if someone installs something like "Clover EFI" it's just a more feature filled replacement UEFI bootloader than the one that's already installed by the manufacturer? Does the UEFI bootloader reside within memory space present on the UEFI chip itself, or is it located on the hard drive? I was under the impression it was located on the chip itself.

If someone *installs* CloverEFI (an emulated EFI firmware based on DUET/EDKII) it will be a case of legacy boot with emulated EFI environment. Basically obtaining hardware information from BIOS, then passing it over to a fake firmware, which resides on a HDD media. The boot process in such case is:
BIOS > MBR > PBR > boot1h > boot > Clover.efi > BOOTLOADER.EFI > OS

Also, in the case of the XPS 15z, when using the "legacy mode", the computer is still operating off UEFI except it is simply emulating the BIOS environment and you use the MBR based OS installations as usual.

That's correct. In fact, Dell went down this road and locked down the machine in emulated BIOS scenario from the factory as the firmware clearly has memory allocation issues. In UEFI mode runtime services fail to start, there are CPU deadlocks and firmware frequently tries to write outside the available memory regions (Fn+F2, QuickSet..).

[thorbsd]

Thanks for the explanation, it cleared a few things up.

So UEFI booting doesn't work properly on the 15z (with the modded A12 BIOS found here)? Or more specifically, it will boot, but there will be issues once you boot into the OS?