I've installed current on a Thinkpad X1 gen 7. The partition table is GPT, but the machine is set up for legacy boot, so there is no EFI partition. Arch Linux ran fine on this machine, booting with syslinux, but Slackware will not boot from the internal disk (an NVME SSD). Lilo installs but will not boot. I did make a boot stick and that works and other than the boot problem, the system seems to work, though I haven't tested it extensively due to the booting issue.

Has anyone had any luck with current on a similar machine?

I'd suggest to use GRUB. As a reminder you'll need a small (2MB is more that enough) unformated partition of type BIOS Boot, if your machine has a GPT. This said, if this machine's firmware allows it I would just set it to boot in EFI mode ithb a GPT and still use GRUB. Your choice anyway :-)

Grub or rEFInd are your friend

Using grub would mean repartitioning (to create the small partition grub needs) and reinstalling. I was hoping to avoid that. If not possible, though, I'll either do that, or restore Arch on this machine. Another possibility is to just live with booting from the USB key until the next release, and hope that the release solves this problem one way or another.

Thanks for the responses.

If your first partition starts @ 1024K you can set up the BIODS Boot partition in the space before. With a simple layout that should be enough. No need to worry about the ailgnment of a partition you never access after boot up.

GParted is GPT aware and capable and makes resizing partitions child's play and is easily done with LiveSlak. FWIW I'm presently running January Current on a T61P Thinkpad. It's so old UEFI wasn't even a dream yet. I have experienced PCs that supposedly support UEFI but early implementations frankly sucked. That could be fixed with a recent bios/uefi firmware update, but not all makes and models continue to produce updates. You probably should check to see if yours is as new as available.

You should be able to use syslinux with Slackware. Maybe that's the simplest option?

My current system is an X1C8 -- I'm using EFI and elilo because I was curious to try EFI. My previous system was an X1C5. That was running Slackware 14.2 (not current) with legacy boot and syslinux. I honestly don't remember why I used syslinux instead of lilo (does lilo support GPT?). Anyway, syslinux (extlinux to be precise) worked fine for me on Slackware 14.2.

I tried syslinux and was not successful. The Slackware Documentation project document I found gives instructions for setting up syslinux on an EFI system, with an EFI partition, which I do not have. So instead, I followed the Arch Linux installation instructions for installing syslinux manually on a GPT/BIOS system. All the required files are included in the Slackware install but this didn't work for some unknown reason.

The question was asked if lilo supports GPT. It does. I am typing this on a desktop system I built with an ASUS micro-itx motherboard, Intel I5 processor and NVME SSD. The system is set up with GPT partition tables but legacy boot, no EFI. Three partitions -- root, boot, home. I used the same install process with this system as with the Thinkpad -- started with the 14.2 installation system and upgraded with slackpkg to current. Booting from the internal SSD works fine on the desktop system with lilo. Which, of course, adds to the mystery of why the same process and partitioning scheme was unsuccessful on the Thinkpad X1, which is a similar hardware setup, though of course the devil is in the details.

Sorry I don't have more help for you. The X1C5 BIOS refused to boot a GPT partition table in legacy mode. But you're able to boot Arch, so that presumably means the X1C7 BIOS has fixed that problem.

What sort of behavior are you getting when you try to boot Slackware on the X1C7?

I used syslinux for a while, but a kernel update, a bump in minor version and I found I could no longer boot. All I ever got was kernel panics. I had scripted much of my build and initrd creation process, so I could not think of anything that should have caused issue. I went over to elilo, no longer use initrd and things have been fine. I don't think initrd was part of the issue though I can't rule it out.

This does not help you, but it might not have been an isolated issue with yourself.

I tried installing syslinux a couple of times, and got the same result, so I don't think I fat-fingered it, though it's still a possibility.

Initial blank screen with a bit of flickering, then an attempt to boot over the network, which fails of course, then you-choose-the-device boot screen.

I should mention that the BIOS is up-to-date.

I will also mention that I bit the bullet and repartitioned, to provide the 1M partition grub requires (and set the bios_grub flag on it with parted). After redoing the 14.2 install, I installed and configured grub, per the Slackware doc. Grub said it was happy and I had a look at the config file and it looked reasonable (4 menu items -- the huge and generic kernels and the symlinks to them). That's the end of the good news. The bad news is that the system still won't boot -- same symptoms. The BIOS config boot security setting is 'legacy boot' and the startup item is 'legacy only'. I give up. I'm restoring Arch to this system. I've wasted much too much time on this. Thanks to all for your attempts to help.

One last thing, just to close the loop -- the restored Arch (with Clonezilla) boots normally with syslinux and the same BIOS settings that I could not make work with Slackware and lilo, syslinux or grub. I realize that sort of points the finger at me, but while I am certainly not infallible, I've been doing this sort of thing for a very long time and have three other systems set up the same way with Slackware current booting (with lilo) and running just fine. I have no explanation for why Slackware would not boot with three different bootloaders on this machine, but Arch boots with syslinux with the same BIOS setup.