Hello Andrew,

When expert configuration option(CONFIG_EXPERT) is enabled, menuconfig offers 
choice of compression algorithm, to compress initial ramfs image. This choice 
is stored into CONFIG_RD_<GZIP/BZIP2/...> variables.

But, usr/Makefile reads from earlier INITRAMFS_COMPRESSION_* variables to set 
the ramfs file extension(.gzip/.bz2/...), which is later(in 
scripts/gen_initramfs_list.sh) used to apply actual compression.

Since none of the INITRAMFS_COMPRESSION_* variables are defined, the resulting 
'usr/initramfs_data.cpio' file remains un-compressed.

The patch attached herein, updates the usr/Makefile to read CONFIG_RD_* 
variables, and also adds support for the Lz4 compression algorithm.

Could you please review it?
==
PS:
IIUC, I think INITRAMFS_COMPRESSION_* variables are not used anywhere at all. 
Though I'm not sure about the EMBEDDED configurations. But if they are not 
used, it could be better to remove their description/references from 
usr/Kconfig and other places.


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