I‘ve got my hands on an second board with older firmware and was able to log in as sysadmin via SSH.
Is there any way to preserve sysadmin or an newly created root user for updating the firmware?
Login in with SSH would be great, but the original firmware is really old In terms of Security Updates.
Also, will the change of the modelname (for full fan support) remain after updating the firmware?
You can not preserve the sysadmin ssh login after an update to newer BMC version. At every reboot of the BMC, the ssh server config will be modified to prevent sysadmin access. And the script that modifies it is in read-only flash!
But adding another user works great. I just edited passwd and shadow directly. they are in the conf directory which is r/w.
I copied the sysadmin record and added it with my name instead. change also the home directory to /conf/user_home/your_username
These setting will remain if you upgrade and preserve setting. If your new firmware requires to also remove setting you will lose it, unfortunately.
I found editing in the BMC limiting so I found a nice way to copy the files to a server and edit there with my favorit editor and then copy back.
You can from the BMC attach a network drive via SMB!
in /dre I created a mountpoint cifs. /dre is r/w. do not create your mount point in /conf. there is an rsync process that runs and keeps /conf and /bkupconf in sync. if it sees a new directory in /conf it will be backed up. I had 2 TB of data it tried to copy!
to mount issue
mount -t cifs -o username=xxx,password=yyyyyy,domain=zzzzz,vers=2.0 //10.0.0.20/share /dre/cifs
insert your credentials and ip and share
After that changing and analyzing files became easier
The BMC firmware from Gigabyte is common for all boards of the same generation. No specific board information is in it. Instead it has all infor for all supported boarda and att BMC boot the right one will be chosen depending on the model stored elsewhere. I have not upgraded the firmware but i am sure the settings of the modelname will remain.
It is not difficult to unpack the BMC firmware on a Linux system and analyse all files in it. It is also possible to modify and pack it back in a new firmware. Unfortunately there is a signature in the end of the file. I have not yet found a way around that! It might be possible to flash an unsigned firmware from the uboot prompt. There are commands for flashing but I have not tried them yet
BR
Peter