Dark Byte Site Admin Reputation: 458
Joined: 09 May 2003 Posts: 25296 Location: The netherlands
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Posted: Wed Nov 29, 2017 10:03 am Post subject: JTAG debugging without special hardware(except an usb cable) |
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..and a gen6+ intel cpu
and a mainboard with a bios that hasn't locked the setup efi vars
and not an Asus because they can't connect wires properly
https://www.win-raid.com/t3250f16-ASUS-Prime-x-Deluxe-and-DCI-debug.html
in short steps: dump your bios file
use uefitool to find the setup program and dump that to disk
use an extractor on that dump to convert it to text
find the efi variable offsets that the above post describes (will be different for you) and change them accordingly (eg efishell ru.efi or setup_var2, etc...)
reboot and connect an usb3 cable between that system and another (don't get a debug cable, get an actual A<->A cable with all wires)
the other system should then detect an usb debug interface.
(if not, reboot and/or try another port, on both systems)
if nothing, then either your cable sucks, or your system doesn't support it(you may have to edit/flash your bios)
then get the intel system debugger, connect and do your thing (it's part of Intel® System Studio Ultimate, which costs around 2200 USD, but there is also a trial you can try)
post your experiences and tries here, it's interesting to know which mainboards, bioses and cpu's work
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notes:
asus may look like it works, but you won't see any cpu's
i bought my usb cable at the local Praxis (some random store for the do-it-yourselfer here in the netherlands)
a lot of places tell you to flash your bios, but you often can also just edit the secret setup variables instead (just don't reset your settings)
tools:
https://github.com/LongSoft/UEFITool/releases (to extract the setup)
https://github.com/LongSoft/Universal-IFR-Extractor/releases (to decode the setup and find the var offsets)
http://ruexe.blogspot.nl/ (easy to use var reader/editor (efi version recommended))
ROM to get data from:
Just go to your mainboard support page and download it there (else try a bios backup tool)
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Last edited by Dark Byte on Wed Nov 29, 2017 1:07 pm; edited 2 times in total |
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