samples: add rule to dump current .config into a defconfig

... and one to restore it, of course.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

1 files changed, 41 insertions, 0 deletions

diff --git a/docs/ct-ng.1.in b/docs/ct-ng.1.in
index a7885166..d6b97610 100644
--- a/docs/ct-ng.1.in
+++ b/docs/ct-ng.1.in
@@ -60,6 +60,47 @@ Samples can be later recalled by calling
 with the target tuple they represent.
 ."
 .TP
+.B defconfig
+Save the current configuration to a mini-defconfig file, that contains only
+the strictly required symbols to reproduce the configuraiton. defconfig files
+are much smaller than a complete .config, so it is easy to send by mail. As
+only non-default symbols are present in a defconfig, it easy to spot the
+meaningfull values. Also, it is easy to use defconfig files with newer
+versions of
+.BR crosstool-NG .
+By default the mini-defconfig is saved to a file named
+.IR defconfig ,
+unless the variable
+.B $DEFCONFIG
+is set, in which case the mini-defconfig will be saved to the file referenced
+by
+.BR $DEFCONFIG .
+
+Note: only the
+.I .config
+file for
+.B crosstool-NG
+is saved. Config files for the components are
+.B not
+saved. Use
+.B saveconfig
+for that
+."
+.TP
+.B olddefconfig
+Configure
+.B crosstool-NG
+using a mini-defconfig file (previously saved with
+.B defconfig
+or manually edited). The default mini-defconfig is rad from the file
+.IR defconfig ,
+unless the vraiable
+.B $DEFCONFIG
+is set, inwhich case the mini-defconfig will be read from the file referenced
+by
+.B $DEFCONFIG
+."
+.TP
 .B build
 Builds the configured toolchain.
 ."