I tracked this down to a bunch of edge-cases in Fujitsu's UEFI implementation, the Linux kernel, and efibootmgr.
The method of restoring access by doing a CMOS-reset (shorting the CL1_CL2 test point) and flashing the BIOS [1] was already known, but I also created a tool [2] that is supposed to restore all relevant settings from within a running Linux installation. Please do make note of the list of supported configurations and of the disclaimer.
A proper kernel-side fix is pending, but it will take some time to land in mainline Linux, linux-stable and the Ubuntu kernel tree respectively.
I tracked this down to a bunch of edge-cases in Fujitsu's UEFI implementation, the Linux kernel, and efibootmgr.
The method of restoring access by doing a CMOS-reset (shorting the CL1_CL2 test point) and flashing the BIOS [1] was already known, but I also created a tool [2] that is supposed to restore all relevant settings from within a running Linux installation. Please do make note of the list of supported configurations and of the disclaimer.
A proper kernel-side fix is pending, but it will take some time to land in mainline Linux, linux-stable and the Ubuntu kernel tree respectively.
[1] https:/ /support. ts.fujitsu. com/ /github. com/timschumi/ ah532-biostools /
[2] https:/