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authorGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2011-03-02 14:52:54 +0100
committerGravatar Peter Korsgaard <jacmet@sunsite.dk>2011-05-09 16:52:22 +0200
commit4e005c47e535fcde9bff04699774bde36f358b38 (patch)
tree0b68179106f9f123b0a3598709eb2c2da6249845 /package/makedevs
parentca520507fc15a8213334a76339a3e6d567e91ea0 (diff)
downloadbuildroot-4e005c47e535fcde9bff04699774bde36f358b38.tar.gz
buildroot-4e005c47e535fcde9bff04699774bde36f358b38.tar.bz2
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>
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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.