bzip2/lzma: don't ask for compression mode for the default initramfs

Impact: Kconfig noise reduction, documentation

The default initramfs is so small that it makes no sense to worry
about the additional memory taken by not double-compressing it.
Therefore, don't bug the user with it.

Also, improve the description of the option, which was downright
incorrect.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/usr/Kconfig b/usr/Kconfig
index a529b4d..588c588 100644 (file)
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -72,23 +72,24 @@ config RD_LZMA
          Support loading of a LZMA encoded initial ramdisk or cpio buffer
          If unsure, say N.
 
+if INITRAMFS_SOURCE!=""
+
 choice
        prompt "Built-in initramfs compression mode"
        help
-         This setting is only meaningful if the INITRAMFS_SOURCE is
-         set. It decides by which algorithm the INITRAMFS_SOURCE will
-         be compressed.
-         Several compression algorithms are available, which differ
-         in efficiency, compression and decompression speed.
-         Compression speed is only relevant when building a kernel.
-         Decompression speed is relevant at each boot.
+         This option decides by which algorithm the builtin initramfs
+         will be compressed.  Several compression algorithms are
+         available, which differ in efficiency, compression and
+         decompression speed.  Compression speed is only relevant
+         when building a kernel.  Decompression speed is relevant at
+         each boot.
 
          If you have any problems with bzip2 or LZMA compressed
          initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
 
-         High compression options are mostly useful for users who
-         are low on disk space (embedded systems), but for whom ram
-         size matters less.
+         High compression options are mostly useful for users who are
+         low on RAM, since it reduces the memory consumption during
+         boot.
 
          If in doubt, select 'gzip'
 
@@ -133,3 +134,14 @@ config INITRAMFS_COMPRESSION_LZMA
          smaller with LZMA in comparison to gzip.
 
 endchoice
+
+endif
+
+if INITRAMFS_SOURCE=""
+# The builtin initramfs is so small so we don't want to bug the user...
+
+config INITRAMFS_COMPRESSION_NONE
+       bool
+       default y
+
+endif