I bought a used LTO4 tape drive with a 8088 SAS connection. Why?
For fun, for backups that feel like they might be more resilient than the shingled magnetic recording hard drives I accidentally bought (thanks Seagate for disclosing that), and for the enjoyment of something so wonderfully mechanical in a world that is very “solid state”.
This necessitated a SAS card purchase, to give myself the ports necessary to actually plug in the tape drive. It seemed unhappy with one of my PCI Express slots, so I moved it up to the primary PCI Express slot — the one you’d usually use for a graphics card.
Now this Arch Linux machine has no need for fancy graphics. The APU integrated graphics on the Ryzen 7 5700G are perfectly adequate.
However, once the SAS card was in the primary PCI Express slot, X11 would no longer start. My SAS card showed up beautifully with lspci, as did the tape drive with lsscsi, but I had to sacrifice the GUI for it. Seems a little extreme, even for me.
X11 would fail with “no screens found” when the amdgpu driver was enumerating screens.
The integrated graphics moved PCI ID
What had happened is that once something is in that primary PCI Express slot, the integrated graphics moved their PCI bus ID.
I first identified where the “VGA controller” had gone with lspci:
08:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] (rev c8)
Then I edited /etc/X11/xorg.conf.d/amdgpu.conf to point the BusID at that new identifier.
For me, it had moved from PCI:7:0:0 to PCI:8:0:0.
And now, I have the delight of a GUI and a SAS card, and a tape drive.