binfmt_misc: add F option description to documentation
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/Documentation/binfmt_misc.txt b/Documentation/binfmt_misc.txt
index 6b1de70..ec83bbc 100644
@@ -66,6 +66,13 @@
This feature should be used with care as the interpreter
will run with root permissions when a setuid binary owned by root
is run with binfmt_misc.
+ 'F' - fix binary. The usual behaviour of binfmt_misc is to spawn the
+ binary lazily when the misc format file is invoked. However,
+ this doesn't work very well in the face of mount namespaces and
+ changeroots, so the F mode opens the binary as soon as the
+ emulation is installed and uses the opened image to spawn the
+ emulator, meaning it is always available once installed,
+ regardless of how the environment changes.
There are some restrictions: