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postmarketos-initramfs 3.7.0 requires manual action for pmOS installs from 2022 or older

January 12, 20253 min. read

Summary

postmarketOS installations from 2022 or older (built with pmbootstrap before this patch) that have a separate boot partition but do not have an entry for /boot in /etc/fstab may be affected by a change in postmarketos-initramfs-3.7.0 that causes /boot to no longer be auto-mounted. Such installations will need to add an entry for /boot to /etc/fstab. Not all such old installations are affected, but it is recommended to add the entry anyway, unless your device specifically does not have a separate boot partition.

Details

New installations of pmOS mount /boot via an entry in /etc/fstab. Before that, installations used to rely on the initramfs script to mount it and intentionally did not have /boot in /etc/fstab. Even after new installations started adding /boot to fstab, the initramfs script continued to support such old installations by probing and mounting /boot if it wasn't listed in fstab.

However this backward-compatibility behavior has been modified in postmarketos-initramfs-3.7.0 to only run if the fstab is empty. This caters to old installations that did not add any custom mounts to fstab, but installations that did add such custom mounts will no longer auto-mount /boot. This can lead to confusing behavior of the device, such as broken audio / wifi / cellular modem after a kernel upgrade, because the device boots an old initramfs with an old kernel from the boot partition but the old version's modules in rootfs have already been deleted. Therefore old installations need to explicitly add an entry for /boot to /etc/fstab.

Adding a /boot entry manually

The procedure is as follows (all commands must be run as root):

  1. Confirm /boot isn't already mounted, with mount | grep /boot. Unmount it if it is.

  2. Run lsblk -fp. Look for the line about the partition with label pmOS_boot. Note the UUID from this line.

  3. Create an entry in /etc/fstab that looks like UUID=$uuid /boot $fstype nodev,nosuid,noexec 0 0.

  4. If a previous kernel upgrade or run of mkinitfs already wrote files to /boot, delete those files so that they do not waste space of the / partition.

  5. Run mount /boot to mount /boot per the new fstab entry. Make sure it succeeds.

  6. Run apk fix --reinstall your-device-kernel-package (eg apk fix --reinstall linux-postmarketos-allwinner for the Pine64 PinePhone) to reinstall the kernel binary into /boot and to regenerate the initramfs. If the package requires working network to be downloaded but network is broken on your device because of missing kernel modules, you may need to download the package file on another device shuttle it over to the broken device via USB network, SD card, mass storage mode, etc, then install it with apk add /path/to/kernel.apk.

  7. Reboot.

For example, if the output of step 2 is:

NAME                 FSTYPE      FSVER LABEL     UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
/dev/mmcblk2
├─/dev/mmcblk2p1     ext2              pmOS_boot d6e15a04-8138-45d1-ac8c-f170697eb001  172.6M    18%
└─/dev/mmcblk2p2     crypto_LUKS                 3d423349-21b7-4bd5-bdfd-da050605d4d8
  └─/dev/mapper/root ext4              pmOS_root ff9c2b3e-6cad-46eb-bff9-12aee03f5ef6   14.7G    42% /

... then the entry in /etc/fstab should look like:

UUID=d6e15a04-8138-45d1-ac8c-f170697eb001 /boot ext2 nodev,nosuid,noexec 0 0

UEFI-boot devices will instead have a vfat partition with a smaller UUID, eg:

NAME                 FSTYPE      FSVER LABEL     UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
/dev/mmcblk0
├─/dev/mmcblk0p1     vfat              pmOS_boot 5478-197C

... for which the entry in /etc/fstab should look like:

UUID=5478-197C /boot vfat nodev,nosuid,noexec 0 0