Why keep all the images?

Posted Oct 16, 2025 17:36 UTC (Thu) by pizza (subscriber, #46)
In reply to: Why keep all the images? by himdel
Parent article: Last-minute /boot boost for Fedora 43

> The one bit I'm confused about is, why the hell does Fedora leave 20 different kernels in /boot?

By default, Fedora keeps 3 kernels, plus a rescue image.

1GB /boot is unable to contain all four with current kernels+firmware.

(I've run into this on multiple systems now)

Why keep all the images?

Posted Oct 16, 2025 19:32 UTC (Thu) by smurf (subscriber, #17840) [Link] (3 responses)

On Debian system a set of kernel+initrd is 50MBytes or so each, so half a GB of /boot is plenty. Let's assume I want a standalone way to restore the machine: that'd add basic network setup, and btrfs' mkfs and "receive". However, those are just five MB or so overall, and if that's still too much, well, I only need to store these once, not in every single initrd.

So, plenty of space.

I don't *quite* get why you'd need a complete self-contained rescue image in /boot. Sure, if your use case is the serial console of some remote system that you can't just plug an USB drive into, fine, but how common is that?

Why keep all the images?

Posted Oct 16, 2025 20:11 UTC (Thu) by pizza (subscriber, #46) [Link] (2 responses)

> On Debian system a set of kernel+initrd is 50MBytes or so each,

Good for you, but this is talking about Fedora, which has different packaging policies and system setup than Debian. For example, a minimal [1] RPi install with Fedora's current defaults fails with a 1GB /boot:

$ du -sch /boot/*6.16.9*
324K /boot/config-6.16.9-200.fc42.aarch64
71M /boot/dtb-6.16.9-200.fc42.aarch64
194M /boot/initramfs-6.16.9-200.fc42.aarch64.img
0 /boot/symvers-6.16.9-200.fc42.aarch64.xz
8.9M /boot/System.map-6.16.9-200.fc42.aarch64
16M /boot/vmlinuz-6.16.9-200.fc42.aarch64
289M total

... 298MB for just *one* kernel. Fedora's defaults to 3 kernels and a rescue image.

[1] Set up with the "Fedora Minimal 42" aarch64 image, with a handful of additional packages installed to drive an RTL-SDR receiver.

Why keep all the images?

Posted Oct 17, 2025 13:38 UTC (Fri) by smurf (subscriber, #17840) [Link] (1 responses)

Ugh. That's a lot.

Why keep all the images?

Posted Oct 17, 2025 13:57 UTC (Fri) by pizza (subscriber, #46) [Link]

> Ugh. That's a lot.

Interestingly, on my x86_64 workstation, the generated intramfs is only 40% of the size of what's on the RPi.

$ du -sch *6.16.10*
284K config-6.16.10-200.fc42.x86_64
75M initramfs-6.16.10-200.fc42.x86_64.img
0 symvers-6.16.10-200.fc42.x86_64.xz
12M System.map-6.16.10-200.fc42.x86_64
17M vmlinuz-6.16.10-200.fc42.x86_64
103M total

...This installation was first set up over a decade ago and upgraded in-place (hardware and software alike) ever since, so some amount of drift from what a fresh install is to be expected. Maybe I'm missing some of the firmware files that are now installed by default?

(x86_64 also lacks the 71MB of per-kernel devicetree files needed for Arm systems. Additionally, most of the firmware packages are utterly irrelevant on an RPi3 that lacks PCIe altogether. But I understand why they have to include everything on a generic image..)