Ubuntu系统内核升级因空间不足失败且无法删除旧内核的问题求助
大家好，我遇到了一个Ubuntu系统升级的棘手问题，希望能得到各位的帮助：
我的系统环境
当前正在运行的内核版本：
uname -r # 输出结果：5.15.0-60-generic
问题：apt upgrade执行失败
我执行apt upgrade时，流程卡在了linux-firmware的配置环节，具体报错如下：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
Get more security updates through Ubuntu Pro with 'esm-apps' enabled:
mc libmagickcore-6.q16-6-extra node-hosted-git-info imagemagick libzmq5
python2.7-minimal libmagickwand-6.q16-6 python2.7 python3-rsa mc-data
node-tar imagemagick-6.q16 libeditorconfig0 libjs-jquery-ui libopenexr24
libsdl2-2.0-0 libmysofa1 libmagickcore-6.q16-6 glances libpython2.7-minimal
libpython2.7-stdlib imagemagick-6-common
Learn more about Ubuntu Pro at https://ubuntu.com/pro
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up linux-firmware (1.187.36) ...
update-initramfs: Generating /boot/initrd.img-5.15.0-60-generic
I: The initramfs will attempt to resume from /dev/dm-2
I: (/dev/mapper/vgubuntu-swap_1)
I: Set the RESUME variable to override this.
Error 24 : Write error : cannot write compressed block
E: mkinitramfs failure cpio 141 lz4 -9 -l 24
update-initramfs: failed for /boot/initrd.img-5.15.0-60-generic with 1.
dpkg: error processing package linux-firmware (--configure):
installed linux-firmware package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
linux-firmware
E: Sub-process /usr/bin/dpkg returned an error code (1)
这里我有个疑问：我明明已经在运行5.15.0-60-generic这个内核了，为什么系统还要尝试生成该版本的initrd镜像文件呢？
排查发现/boot分区空间不足
我猜测问题根源是磁盘空间不够，于是执行df -H查看分区使用情况：
df -H # 输出结果： Filesystem Size Used Avail Use% Mounted on udev 135G 0 135G 0% /dev tmpfs 28G 3.0M 28G 1% /run /dev/mapper/vgubuntu-root 982G 838G 94G 90% / tmpfs 136G 296M 135G 1% /dev/shm tmpfs 5.3M 4.1k 5.3M 1% /run/lock tmpfs 136G 0 136G 0% /sys/fs/cgroup /dev/nvme0n1p2 738M 588M 97M 86% /boot /dev/nvme0n1p1 536M 6.4M 530M 2% /boot/efi /dev/sda2 7.0T 1.5T 5.2T 23% /mnt/usb-8tb tmpfs 28G 25k 28G 1% /run/user/125 tmpfs 28G 70k 28G 1% /run/user/1000
可以看到/boot分区使用率已经达到86%，剩余空间仅97M，应该是空间不足导致initramfs生成时写入失败。
尝试删除旧内核但无法释放空间
为了腾出/boot的空间，我打算删除旧内核，先查看了已安装的内核镜像列表：
dpkg-query -Wf '${Installed-Size}\t${Package}\n' | sort -n | grep linux-image # 输出结果： 20 linux-image-generic-hwe-20.04 9520 linux-image-5.8.0-43-generic 9927 linux-image-5.11.0-36-generic 9928 linux-image-5.11.0-37-generic 9933 linux-image-5.11.0-38-generic 9956 linux-image-5.13.0-25-generic 9956 linux-image-5.13.0-27-generic 9965 linux-image-5.13.0-28-generic 9965 linux-image-5.13.0-30-generic 9965 linux-image-5.13.0-35-generic 9968 linux-image-5.13.0-37-generic 9968 linux-image-5.13.0-39-generic 9971 linux-image-5.13.0-40-generic 9971 linux-image-5.13.0-41-generic 9971 linux-image-5.13.0-44-generic 9972 linux-image-5.13.0-48-generic 9973 linux-image-5.13.0-51-generic 9973 linux-image-5.13.0-52-generic 10775 linux-image-5.15.0-41-generic 10778 linux-image-5.15.0-43-generic 11196 linux-image-5.15.0-46-generic 11207 linux-image-5.15.0-52-generic 11208 linux-image-5.15.0-50-generic 11209 linux-image-5.15.0-48-generic 11210 linux-image-5.15.0-53-generic 11212 linux-image-5.15.0-56-generic 11214 linux-image-5.15.0-57-generic 11215 linux-image-5.15.0-58-generic 11223 linux-image-5.15.0-60-generic 11499 linux-image-5.11.0-40-generic 11502 linux-image-5.11.0-41-generic 11502 linux-image-5.11.0-43-generic 11504 linux-image-5.11.0-44-generic 11504 linux-image-5.11.0-46-generic
但奇怪的是，当我尝试删除任意一个旧内核时，系统提示只会释放0字节的空间，这让我完全摸不着头脑。
希望大家能帮我解答两个核心问题：
- 为什么我已经在运行
5.15.0-60-generic内核，系统还要更新它的initrd文件？ - 为什么删除旧内核无法释放
/boot空间？有没有正确的清理方法？
非常感谢各位的指导！
备注：内容来源于stack exchange，提问作者Nik
