buildrootschalter/support/misc/target-dir-warning.txt
Thomas Petazzoni 9226a9907c Warn the user about the usage of output/target as the root filesystem
A very common mistake done by our users is that they use
output/target/ directory as their root filesystem. Even though this is
loudly documented in our Buildroot manual, people don't read
documentation, so it is not sufficient.

This patch adds a text file named
output/target/THIS_IS_NOT_YOUR_ROOT_FILESYSTEM which explains why
output/target isn't appropriate to use as the root filesystem. The
process is:

 * At the beginning of the build, right after the skeleton has been
   copied, support/misc/target-dir-warning.txt is copied to
   output/target/THIS_IS_NOT_YOUR_ROOT_FILESYSTEM

 * In the filesystem images creation code, this file is removed before
   launching fakeroot, and restored right after that, so that this
   file is not present in the generated root filesystem images.

Note that the file has not been added to the default skeleton for two
reasons:

 * It would have annoying to have in our source tree a file named in
   capital letters inside system/skeleton/

 * The proposed way works even if the user uses a custom skeleton.

[Peter: fixed typo]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Juha Lumme <juha.lumme@gmail.com>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
2012-11-17 17:12:49 +01:00

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Warning!
========
This directory does *not* contain the root filesystem that you can use
on your embedded system. Since Buildroot does not run as root, it
cannot create device files and set the permissions and ownership of
files correctly in this directory to make it usable as a root
filesystem.
For that reason, do *not* use the contents of this directory to mount
your root filesystem over NFS or copy the contents of this directory
to a SD card or USB key, thinking it will work as the root filesystem
for your embedded system. It will simply *not* work.
Instead, if you need a usable root filesystem, please select one of
the filesystem image formats available in the Buildroot configuration
interface (make menuconfig or others) in the "Filesystem images"
sub-menu. If you want to get a filesystem image that you can easily
extract to your SD card or to some directory exposed through NFS,
please use the "tar the root filesystem" option. It will generate a
images/rootfs.tar image in your Buildroot output directory, which you
can extract as root:
sudo tar -C /destination/of/extraction -xf images/rootfs.tar
Those image files are created using the contents of the target/
directory, but there is a post-processing step to create device files
and set owernship/permissions properly even if Buildroot does not run
as root.