Request: UEFI mod Bios for Precision T3500

[anf]

Hi,
I'm new to this and I wanted to know if a mod of this bios works out without bricks. Will I be able install the same mod on my same pc (T3500) without any bricks or having to use any extra equipment?

[Sml6397]

Hello everyone,

There are many concurrent requests in this thread for different machines. I am going to outline the requests below so nothing gets confused (mostly for my own reference):

@StarPrince, this thread's creator, has requested a mod for their Dell Precision T3500 desktop, which has a specialized Dell Phoenix BIOS version A17. I - nor anyone I am aware of - can currently perform this type of mod as Dell specialized their Phoenix non-UEFI BIOS images. I am going to try to figure out how to modify this image using a picture of a BIOS menu you provided in Post #10. I am going to look at the official BIOS update (BIOS image obtained via "...A17.exe -writehdrfile") to figure this out. Before any flashing of (purely) experimental mods, we are waiting on the CH341A programmer to arrive to get a clean backup that can be used to recover the BIOS chip if it gets bricked.

@StarPrince has a second BIOS mod request, first mentioned in Post #9 for a Dell Latitude 3340 laptop with a link to an official BIOS update. Pictures of this BIOS's menus are in Post #11. This BIOS is actually UEFI and is the one that contains Intel BootGuard. Since BootGuard is disabled (confirmed in picture from HWiNFO64 in Post #17), I can begin the modding process! Even if something did go wrong, we are going to get a full backup (will give instructions in the next post) that your new CH341A can restore anyways.

@ITronLegends has a third BIOS mod request for the Dell T3500 desktop as well. You asked if you could flash the T3600 BIOS since it has UEFI support. This tends to be possible, but there is increased risk compared to normal because the system itself may not automatically be configured to work properly with UEFI, which could create a brick. I'd recommend purchasing the CH341A that StarPrince mentioned in Post #20. This way, if you take a backup with the CH341A before trying the flash, you can always flash the backup onto the BIOS chip if something goes wrong during the T3600 BIOS test. Otherwise, I will mod your T3500 BIOS as soon as I figure out Dell Phoenix BIOS.

Figuring out Dell Phoenix BIOS is now at the top of my TODO list. Thanks for the continued patience.

@anf,
Yes, once StarPrince confirms that the T3500 BIOS mod flash works, you will be able to flash the upcoming BIOS mod onto your computer without special hardware or elevated risk of bricks (every BIOS flash - update or mod - bears a very slight chance of something going wrong). Please do not flash any mods I publish for the T3500 until StarPrince confirms that it works because they have a hardware programmer if something goes wrong when flashing this experimental mod. I say experimental because it is a special type of Phoenix BIOS - Dell Phoenix BIOS, which I have never modded before.

[ITronLegends]

Ah thanks!

[anf]

Ok, thanks for the reply.

[StarPrince]

Hello Sml,

Im sorry for any confusion occurred but it wasn't intended for sure, however, this post is for modding Precision T3500 UEFI/Secure Boot of latest bios version A17 exactely as you mentioned, the second thing about latitude 3340 i just gave it as an example if we can extract anything from this type of bios as it is already UEFI/Secure Boot included in the bios, just for our research for T3500 modding purpose, that is all.

[ITronLegends]

Any updates?

[Sml6397]

Terribly sorry, forgot about this request.

I will open the 3500 BIOS update tonight and begin looking for strings from the BIOS menu screenshots in this thread. If I can find them in plain text, then this gives me a lot to go on in terms of figuring out a way to unlock or unhide settings. If I am able to make progress, I will post regular updates.

[Sml6397]

I have found the module that contains most of the strings that show up in the BIOS menus. It is titled "3C_6.ROM". The module is 347KB, the third largest module. You can find this module by running "T3500A17.exe -writehdrfile" (Hint: if running in Powershell, type "./" before the command).

A section of the file beginning at offset 0x21920 can be seen in the attached photo. You may notice that many of the strings there are the names of the top level menus in your BIOS Setup Utility.

Now we have to figure out what calls to those strings. In a standard (ie: non-Dell) Phoenix BIOS, you would take the beginning offset of a menu/sub-menu/setting string (in the STRINGS module), flip the bytes (Little Endian), search for it in the large jump table near the beginning portion of the file it shows up in (STRINGS), take the result's beginning offset, and search for those two bytes reversed in another module (TEMPLAT). This would take you to two bytes after the beginning of the set of bytes that handles that particular menu/sub-menu/setting. This set of bytes is usually 16-32 bytes long, with the size specified by the second byte from the beginning of the set of bytes.

I suspect that we will likely encounter something along these lines, though it is too early to close off other options. Essentially, we want to find the internal (same module) or external (different module) reference that calls these strings found in the 3C_6.ROM file.

I will post further updates as I learn more.

[ITronLegends]

Interesting. I don't know anything about this so...

[ITronLegends]

Hmm updates? It's been a long time