Does Trisquel 8 64-bit support UEFI installation?
I recently purchased an Nth-hand 1st-gen ThinkPad Helix (IvyBridge) and flashed the official firmware with the latest embedded controller (EC), for there is currently no coreboot support for this model.
Then I wanted to purge the preloaded Losedows after updating the firmware. Strangely, most GNU/Linux distributions that support UEFI and Losedows 7/8.x/10 can boot smoothly in UEFI mode. But everything invariably fails to boot in Legacy (CSM) mode, even if I tried Losedows USB installation media using Microsoft's official creation tool.
What's stranger, I once tried GNU/Linux Mint (just for testing purposes) in UEFI mode. When I rebooted the computer after a reportedly successful installation, the system booted. But I then inspected the /boot/efi mount point and only to find that the ESP was empty... I wondered how did the computer boot: for UEFI mode, there was nothing in the ESP; and for Legacy mode, I didn't even create a BIOS Boot partition.
I haven't tried Trisquel yet because my ordered Atheros-htc USB WLAN adapter hasn't arrived yet. I also didn't try to install many GNU/Linux distributions with UEFI support on the SSD, since this could make my UEFI boot option field a terrible mess.
UPDATE: Problem solved. This is because certain unknown defect of the keyboard base. I purchased another Helix and successfully installed Trisquel (Legacy BIOS mode) using the good new keyboard base.
I once booted Mint using UEFI mode and subsequently installed it. But owing (thanks) to the broken-beyond-repair installers of Ubuntu and Mint, which always fail on certain UEFI firmware with CSM enabled, the ESP remained empty and there was no boot option named "ubuntu" in the UEFI firmware. Yet I was, surprisingly, able to boot Mint from the internal SSD anyway. I therefore guessed that there was nothing wrong with the UEFI firmware, since the fallback boot loader did work.
Then there must be certain hardware failure. Before disassembling the tablet itself, I firstly tried to replace the keyboard base and, by doing so, solved the problem.
Yeah, my Lenovo ThinkPad T420 boots Trisquel 8 using UEFI mode. It is one of the very few UEFI successes I've had over the years, in fact.