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

[jkbuha]

Nice work guys but sadly it didn't work on the 15z.

USB in closest left slot on boot doesn't switch on, and when it does it goes straight to BIOS. Maybe it's because there is no END key on 15z (only Fn+Right combo). Or because the battery is integrated.

Still - nice work on all the other Dell's guys - once this is firmed up I'll add it to the first post

[Yaks]

Hey i've been following closely and really impressed with what you guys have achieved (specially jbukha, timewalker and kasar).

Does your last post suggest we can mod bioses, and try them out before flashing it for real? So if we boot using a modded bios on USB we can test without risking bricking our machines?

[TimeWalker]

If it goes to BIOS and doesn't stay there sitting with black screen then it's obviously doing something.. or expects something from you. Have you tried the method of creating the capsule that I had suggested?
The battery doesn't need to be taken out, so it's not a concern at all. Did you look inside the SystemFatLitePei.efi and SystemCdExpressPei.efi modules to see what is the name of the .cap file that it's looking for? Also try other USB ports on your system.

[kasar]

@yask

thanks and nice idea man

yeah, the oposite thing should be posible thanks to what timewalker said about the bios.cap file setting up.

theorically it should be posible to temporally load a modded bios without flashing anything with that method

[TimeWalker]

Hey i've been following closely and really impressed with what you guys have achieved (specially jbukha, timewalker and kasar).

Does your last post suggest we can mod bioses, and try them out before flashing it for real? So if we boot using a modded bios on USB we can test without risking bricking our machines?

Thanks!
That is actually a really good use of this feature which I haven't really thought of previously.
It sure is a way of trying out what you've just created before actually flashing it to the chip .. which is a ton safer. One would always have to remove the firs padding layer though... or make it automated by writing a piece of software.

[jkbuha]

Yes I did - truncated the first 180000h bytes and saved it to bios.cap. Nada.
I don't have the bandwidth to go thru the bios files but will do so this weekend. Hopefully with some progress.

On another note guys - if we nail this universal Dell BIOS recovery method we'll have made this forum super famous for two reasons now

[TimeWalker]

I believe the name is case sensitive, so it has to be exactly BIOS.cap .. because PEI modules look for this in the root of the external media.
I indeed hope you can figure this recovery thing for 15z

[krzysio30]

I made test
l702x with modded a16 bios installed

FAT32 formated usb drive with BIOS.cap at the root
one test modded A16 backup (Universal BIOS Backup Toolkit 2.0)
second test removed the first 180000h bytes of the file F33E367F-41D2-4201-9CB7-AFA63DCCEEC9_x_x.ROM (BIOS1.WPH from the OEM updater)
1 - laptop turned off
2 - unpluged the AC
3 - plugged the usb drive on the laptop.
4 - hold END key
5 - pluged the AC and relase the END key 1 second after the power cord is in.
6 - Fans started to spin fast, power led blinked fast, and the usb too.
7 - DELL logo and STOP
   
8 - I repeated the whole process by hitting F2 key to enter at the setup while the bios was booting from the usb drive and
   


What could be wrong ???

[TimeWalker]

Actually you are correct ... SATA AHCI efi drivers are missing from the stripped copy of BIOS apparently. But yet the HDD is seen from the Boot menu:

Slamming F12 as soon as it boots and selecting HDD from boot order appears to start loading Windows but then it just BSODs and restarts.

The most popular Blue Screen of Death error in Windows is the STOP 0x0000007B error, sometimes called the 0x7b error or the "INACCESSIBLE BOOT DEVICE" BSOD.

If using a dump of the on-chip BIOS as BIOS.cap Windows does the same thing. Interestingly enough I can boot OSX (gives Still waiting for root device though so ACHI is definitely missing) or Ubuntu perfectly fine ... but these aren't the OSes one could look forward to flash the corrupted BIOS. So this has to be looked into ... dang it, though we nailed it.
Also I just recalled something - there's going to be a feature in Windows 8 to create a standalone USB drive with an installation which you could run from your flashdrive - life saver for this situation. But it requires 16Gb+ USB stick to do this ..

[krzysio30]

........ Also I just recalled something - there's going to be a feature in Windows 8 to create a standalone USB drive with an installation which you could run from your flashdrive - life saver for this situation. But it requires 16Gb+ USB stick to do this ..

16 GB USB will be enough or I need more ??