Hello Andrew,

+-- On Tue, 29 Oct 2013, Andrew Morton wrote --+
| On Tue, 15 Oct 2013 20:25:57 +0530 (IST) P J P <ppandit@redhat.com> wrote:
| This patch breaks my x86_64 allmodconfig build, because I don't have
| the lz4 executable installed:
| 
| /usr/src/25/scripts/gen_initramfs_list.sh: line 307: lz4: command not found
| make[1]: *** [usr/initramfs_data.cpio.lz4] Error 1
| 
| This obviously isn't acceptable!

  Oops! '$ make allmodconfig' seems to enables all compression algorithms; So 
the last one overrides the previous choices in usr/Makefile.

===
...
CONFIG_RD_GZIP=y
CONFIG_RD_BZIP2=y
CONFIG_RD_LZMA=y
CONFIG_RD_XZ=y
CONFIG_RD_LZO=y
CONFIG_RD_LZ4=y
===

Please see an updated patch herein. I've patched 'gen_initramfs_list.sh' 
script to check if a selected compression command is accessible or not; And 
fall-back to the default gzip(1) format when it is not. usr/Makefile also 
defaults to '.gz' format when all are enabled.

I hope this works well; Sorry about the trouble though.

Thank you!
--
Prasad J Pandit / Red Hat Security Response Team