Hi,
I'm trying to set up a Linux system that will be able to have a rootfs
essentially in a vfat filesystem. This means I don't have support for
device files, links, etc. (permissions aren't a huge concern in this
particular case). My idea was to use unionfs to combine a vfat, which
provided the bulk of the files, with a tmpfs, which would only be used for
files that used special features that vfat doesn't support. For example,
after building the union, /dev would be generated dynamically on boot on
the union, which would put all these files on the tmpfs rather than the
vfat.
Here is what I've been able to do so far using unionfs:
# ls -l
total 5
drwxrwxrwt 2 root root 140 Jan 5 22:18 ram
drwxr-xr-x 2 root root 4096 Jan 5 21:22 union
drwxr-xr-x 2 root root 512 Jan 5 22:01 vfat
# mount | grep '/root/cat'
/dev/loop0 on /root/cat/mnt/vfat type vfat (rw)
tmpfs on /root/cat/mnt/ram type tmpfs (rw)
# mount -t unionfs -o dirs=/root/cat/mnt/vfat=rw:/root/cat/mnt/ram=rw unionfs
union
# touch union/test
# ls vfat/
test
Everything is fine so far. vfat has higher precedence than ram, so that's
where the file creation goes first. Now, this is what happens when I try
to create a device file:
# mknod union/tty c 5 0
mknod: `union/tty': Operation not permitted
This is probably expected to the unionfs developers, but I don't
understand why this happens. I would expect unionfs to get an error while
trying to create the file on the vfat branch, but to retry the operation
in the ram branch. There, it should succeed because tmpfs supports device
files just fine. Instead, it appears to me that it bails out on the first
attempt.
Chances are that this behavious is as it is for a good reason. Perhaps
some one could at least explain? Any workarounds?
Thanks in advance,
Catalin
-----------------------------------------
Catalin Patulea VV Volunteer 2002,3
http://vv.carleton.ca/~cat/ VV HI 2004,5
[EMAIL PROTECTED] VV Server Admin 2006
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