Fedora 38 mini-review on the Blackbird and Talos II

This article would have come out sooner except I also wanted to test building Firefox in Fedora 38, and then when I tried to run libnxz/power-gzip to test out the POWER9 nest accelerator make check made my daily driver Talos II machine check and caused Hostboot to guard out the entire CPU with the NVMe drives attached (and fixing that caused Petitboot to barf on a stuck XFS log entry again, requiring a trip to the Blackbird to mount and repair it). But here we are.

As I always say in these mini-reviews, Fedora was one of the first mainstream distributions to support POWER9 out of the box, it's still one of the top distributions OpenPOWER denizens use and its position closest to the bleeding, ragged edge is where we see problems emerge first and get fixed (hopefully) before they move further downstream. That's why it's worth caring about it even if you yourself don't run it.

Also, as usual, recall both my T2 and Blackbird are configured to come up in a text boot instead of gdm and I start KDE manually from there. I still test GNOME on both systems, but I've pretty much entirely migrated over to KDE Plasma, and you should never have considered my GNOME testing to be exhaustive anyway. I strongly recommend a non-graphical boot as a recovery mechanism in case your graphics card gets whacked by something or other. On Fedora this is easily done by ensuring the symlink /etc/systemd/system/default.target points to /lib/systemd/system/multi-user.target.

Because of issues with dnf kernel updates still sometimes not updating the grub config (basically bug 1921479, showing messages like 0ed84c0-p94177c1: integer expression expected during the process), I've added a little extra paranoia to the usual install dance. To wit:

dnf upgrade --refresh # upgrade prior system and DNF
grub2-mkconfig -o /boot/grub2/grub2.cfg # force grub to update
dnf install dnf-plugin-system-upgrade # install upgrade plugin if not already done
dnf system-upgrade download --refresh --releasever=38 # download F38 packages
dnf system-upgrade reboot # reboot into upgrader

This went fairly smoothly on both systems. Other than a copr package with a stale prerequisite I had to remove, there were no issues or conflicts with the 38 packages. As long as you manually select the new kernel in Petitboot before the system starts, you'll get some sort of installation screen. On the Blackbird's HDMI output from the ASPEED BMC framebuffer, the same friendly GUI installer will appear as in prior releases:

But even without using BMC video, like on the T2 with the Raptor-BTO WX7100 workstation card, as before you'll still get to see the install log live as text (which by now I've found more useful anyway). If you forget to manually select the kernel and the system comes up to an apparently black screen, you can either monitor on the serial port, or from a connected system viewing the serial console over the BMC's web server, or by logging into another VTY with CTRL-ALT-F2 or as appropriate as root and periodically issuing dnf system-upgrade log --number=-1 to watch log updates.

The update did not cause a stuck XFS log entry this time on either the Blackbird or the T2, but after the reboot I did need to do one more grub2-mkconfig -o /boot/grub2/grub2.cfg and a restart to ensure the right kernel and version were being used. Currently the kernel version as of this writing is 6.2.14.

Our first stop on the BMC-only Blackbird is GNOME on Wayland, started (awkwardly) with XDG_SESSION_TYPE=wayland /usr/libexec/gnome-session-binary --builtin. This configuration hasn't visibly improved any from Fedora 37; there are still prominent artifacts moving windows around and display through the HDMI adapter is still limited to 1024x768.

Performance wasn't hideous but the artifacts were distracting. I couldn't get a screenshot of it in Spectacle so I just grabbed a picture on my Pixel 7 Pro. However, the story isn't a whole lot better in GNOME on X11:
While we now have a full 1920x1020, you can see that the title bar still isn't being painted correctly. This occurred with most of the applications I tried. I consider this a critical fault due to the smearing, so I can't really recommend GNOME at all under any window system if you're using baseline BMC graphics. And KDE?
Well, it works fine. I use KDE on the T2, so now I'm using it on the Blackbird as well. If you really prefer a Gtk default, Xfce should also serve you well.

On the T2 with its AMD GPU, however, I dumped GNOME because of libadwaita encroaching on my customizations; even my shell theme has stopped working now. But the basics are fine: there are no more obvious problems with CTM, and performance seems similar to 37 with no obvious issues in Wayland or X11. On KDE, my customizations persisted without having to rework any of them, which is why I've converted fully over to KDE.

Overall, the F38 update was smooth and it runs pretty much like F37. If you had no problems with F37, you'll probably have no problems with this; you just won't see much improvement in some of the longstanding annoyances either.


  1. Excellent writeup - I've been putting off migrating my F37 Blackbird over until your experience. As I'm not running XFS anywhere, I shouldn't run into that issue.

    One quick question: am I likely to run into any issues following these steps to swap Gnome out for Fedora prior to the change? Or should I push that until afterward?

    1. No, that's basically what I did a couple versions ago, except you may need to alter your .xinitrc to ensure you're running what you think you should be, or enter your desktop environment with a different command (like startplasma-x11, etc.). I don't think it matters much to do it before or after but it might be simpler to do it after so that the initial dnf refresh doesn't pull down a lot of packages that will just get upgraded again right away.

  2. I think these artifacts are a Gnome/Gtk problem, in Fedora 37 they also occur, for example, in the Weather application but not in Gnome-Terminal.

    Kernel 2.6.14-200 is the fastest release in Fedora 37/38 that I've tested, reading an average of 6.6 GB/s, latency averaging 0.05 ms. The next kernel 6.2.15-200 is down to 4.5 GB/s and 0.09 ms.

    I tried to use KDE but it had terrible delays in drawing the background when resizing windows, does this still happen?

    1. I haven't noticed those sorts of delays on the Blackbird or T2, but I certainly don't discount the possibility. That said, I've been very happy with KDE's redraw performance.


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