Allow several device tables and split in two parts our device table

This allows to have a device table for all directories/files and
another device table for the device files themselves. Both are needed
for static /dev, but only the first one is needed when
devtmpfs/mdev/udev are used.

We take this opportunity to move the documentation of the device table
format in a common location, package/makedevs/README.

[Peter: simplify code slightly, fix indentation]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

1 files changed, 35 insertions, 0 deletions

diff --git a/package/makedevs/README b/package/makedevs/README
new file mode 100644
index 000000000..6c54052ee
--- /dev/null
+++ b/package/makedevs/README
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+When building a target filesystem, it is desirable to not have to
+become root and then run 'mknod' a thousand times.  Using a device
+table you can create device nodes and directories "on the fly".
+
+You can do all sorts of interesting things with a device table file.
+For example, if you want to adjust the permissions on a particular
+file you can just add an entry like:
+
+  /sbin/foobar        f       2755    0       0       -       -       -       -       -
+
+and (assuming the file /sbin/foobar exists) it will be made setuid
+root (regardless of what its permissions are on the host filesystem.
+
+Furthermore, you can use a single table entry to create a many device
+minors.  For example, if I wanted to create /dev/hda and
+/dev/hda[0-15] I could just use the following two table entries:
+
+  /dev/hda    b       640     0       0       3       0       0       0       -
+  /dev/hda    b       640     0       0       3       1       1       1       15
+
+Device table entries take the form of:
+
+<name>    <type>      <mode>  <uid>   <gid>   <major> <minor> <start> <inc>   <count>
+
+where name is the file name,  type can be one of:
+
+      f       A regular file
+      d       Directory
+      c       Character special device file
+      b       Block special device file
+      p       Fifo (named pipe)
+
+uid is the user id for the target file, gid is the group id for the
+target file.  The rest of the entries (major, minor, etc) apply only
+to device special files.