After upgrading to linux-libre 4.20, and again tested with 4.20.3, an
aarch64 system failed to boot (using 4.19.10 worked fine):

[    3.692351] device-mapper: ioctl: 4.39.0-ioctl (2018-04-03) initialised: dm-devel@redhat.com
ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether /dev/sda6 is mounted.
/dev/sda6: clean, 596262/6553600 files, 7663147/26214400 blocks
[    3.948786] EXT4-fs (sda6): Cannot load crc32c driver.
ERROR: In procedure mount:
In procedure mount: No such file or directory

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Workaround or fix was to add to config.scm:

(initrd (append (list "crc32c_generic" ... ) %base-initrd-modules))


4.19.10 and earlier worked fine without this addition; as far as I can
see the relevent kernel configurations are all present; but some
behavior changed with the ext4 driver; Is the initrd no longer including
soft module dependencies? (e.g. for optional ext4 features)


This seems similar to Debian bug:

  https://bugs.debian.org/819725


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