Uhhuh. I've never used cramfs on a ramdisk, but I have a guess: cramfs
_really_ wants to have 4kB blocks. I bet your ramdisk has 1kB blocks (the
Have you tried using
as a boot option?
> The cramfs docs are contradictory btw; the kernel help says 'doesn't
> support hardlinks', and Documentation/filesystems/cramfs.txt says
> 'Hardlinks are supported, but...'. I made my cramfs with and without
> hardlinks (to busybox); but that didn't affect whether it mounted. I
> haven't tested whether this fixes the 'access beyond end of device'
The documentation is right. cramfs does not support hardlinks.
HOWEVER, cramfs gives you the _effect_ of hardlinks by having mkcramfs
notice that two files are the same (whether hardlinked or not), and
re-using the data block pointer. This gives you all the space savings of
hard links, with a twist: you can actually have two separate files, with
separate permissions and owners etc, and they will be "linked" in the data
linking meaning if the contents are the same.
So you could think of the cramfs links as being a superset of hardlinks.
Or a "corruption" of hardlinks. The file shows up as two different files
as far as unix tools are concerned (nlink == 1, different inode numbers
etc), but becasue of the data sharing they have the disk usage pattern of
The reason you don't have (and cannot have) _true_ hardlinks is obvious:
ramfs does not have inodes. It only has directory entries with enough
information to fill in a linux inode structure. Kind of like FAT, in that
This, btw, also means that it's counterproductive to try to save space on
the source tree that is crammed by trying to find identical files and
hardlinking them - mkcramfs will do the same thing regardless.
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