linux/usr/Kconfig

238 lines
8 KiB

initramfs: allow again choice of the embedded initram compression algorithm Choosing the appropriate compression option when using an embedded initramfs can result in significant size differences in the resulting data. This is caused by avoiding double compression of the initramfs contents. For example on my tests, choosing CONFIG_INITRAMFS_COMPRESSION_NONE when compressing the kernel using XZ) results in up to 500KiB differences (9MiB to 8.5MiB) in the kernel size as the dictionary will not get polluted with uncomprensible data and may reuse kernel data too. Despite embedding an uncompressed initramfs, a user may want to allow for a compressed extra initramfs to be passed using the rd system, for example to boot a recovery system. 9ba4bcb645898d ("initramfs: read CONFIG_RD_ variables for initramfs compression") broke that behavior by making the choice based on CONFIG_RD_* instead of adding CONFIG_INITRAMFS_COMPRESSION_LZ4. Saddly, CONFIG_RD_* is also used to choose the supported RD compression algorithms by the kernel and a user may want to support more than one. This patch also reverts commit 3e4e0f0a875 ("initramfs: remove "compression mode" choice") restoring back the "compression mode" choice and includes the CONFIG_INITRAMFS_COMPRESSION_LZ4 option which was never added. As a result the following options are added or readed affecting the embedded initramfs compression: INITRAMFS_COMPRESSION_NONE Do no compression INITRAMFS_COMPRESSION_GZIP Compress using gzip INITRAMFS_COMPRESSION_BZIP2 Compress using bzip2 INITRAMFS_COMPRESSION_LZMA Compress using lzma INITRAMFS_COMPRESSION_XZ Compress using xz INITRAMFS_COMPRESSION_LZO Compress using lzo INITRAMFS_COMPRESSION_LZ4 Compress using lz4 These depend on the corresponding CONFIG_RD_* option being set (except NONE which has no dependencies). This patch depends on the previous one (the previous version didn't) to simplify the way in which the algorithm is chosen and keep backwards compatibility with the behaviour introduced by 9ba4bcb645898 ("initramfs: read CONFIG_RD_ variables for initramfs compression"). Link: http://lkml.kernel.org/r/57EAD77B.7090607@klondike.es Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <klondike@klondike.es> Cc: P J P <ppandit@redhat.com> Cc: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-14 15:06:04 -08:00
initramfs: fix disabling of initramfs (and its compression) Commit db2aa7fd15e8 ("initramfs: allow again choice of the embedded initram compression algorithm") introduced the possibility to select the initramfs compression algorithm from Kconfig and while this is a nice feature it broke the use case described below. Here is what my build system does: - kernel is initially configured not to have an initramfs included - build the user space root file system - re-configure the kernel to have an initramfs included (CONFIG_INITRAMFS_SOURCE="/path/to/romfs") and set relevant CONFIG_INITRAMFS options, in my case, no compression option (CONFIG_INITRAMFS_COMPRESSION_NONE) - kernel is re-built with these options -> kernel+initramfs image is copied - kernel is re-built again without these options -> kernel image is copied Building a kernel without an initramfs means setting this option: CONFIG_INITRAMFS_SOURCE="" (and this one only) whereas building a kernel with an initramfs means setting these options: CONFIG_INITRAMFS_SOURCE="/home/fainelli/work/uclinux-rootfs/romfs /home/fainelli/work/uclinux-rootfs/misc/initramfs.dev" CONFIG_INITRAMFS_ROOT_UID=1000 CONFIG_INITRAMFS_ROOT_GID=1000 CONFIG_INITRAMFS_COMPRESSION_NONE=y CONFIG_INITRAMFS_COMPRESSION="" Commit db2aa7fd15e85 ("initramfs: allow again choice of the embedded initram compression algorithm") is problematic because CONFIG_INITRAMFS_COMPRESSION which is used to determine the initramfs_data.cpio extension/compression is a string, and due to how Kconfig works it will evaluate in order, how to assign it. Setting CONFIG_INITRAMFS_COMPRESSION_NONE with CONFIG_INITRAMFS_SOURCE="" cannot possibly work (because of the depends on INITRAMFS_SOURCE!="" imposed on CONFIG_INITRAMFS_COMPRESSION ) yet we still get CONFIG_INITRAMFS_COMPRESSION assigned to ".gz" because CONFIG_RD_GZIP=y is set in my kernel, even when there is no initramfs being built. So we basically end-up generating two initramfs_data.cpio* files, one without extension, and one with .gz. This causes usr/Makefile to track usr/initramfs_data.cpio.gz, and not usr/initramfs_data.cpio anymore, that is also largely problematic after 9e3596b0c6539e ("kbuild: initramfs cleanup, set target from Kconfig") because we used to track all possible initramfs_data files in the $(targets) variable before that commit. The end result is that the kernel with an initramfs clearly does not contain what we expect it to, it has a stale initramfs_data.cpio file built into it, and we keep re-generating an initramfs_data.cpio.gz file which is not the one that we want to include in the kernel image proper. The fix consists in hiding CONFIG_INITRAMFS_COMPRESSION when CONFIG_INITRAMFS_SOURCE="". This puts us back in a state to the pre-4.10 behavior where we can properly disable and re-enable initramfs within the same kernel .config file, and be in control of what CONFIG_INITRAMFS_COMPRESSION is set to. Fixes: db2aa7fd15e8 ("initramfs: allow again choice of the embedded initram compression algorithm") Fixes: 9e3596b0c653 ("kbuild: initramfs cleanup, set target from Kconfig") Link: http://lkml.kernel.org/r/20170521033337.6197-1-f.fainelli@gmail.com Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Acked-by: Nicholas Piggin <npiggin@gmail.com> Cc: P J P <ppandit@redhat.com> Cc: Paul Bolle <pebolle@tiscali.nl> Cc: Michal Marek <mmarek@suse.cz> Cc: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-02 14:46:22 -07:00
initramfs: allow again choice of the embedded initram compression algorithm Choosing the appropriate compression option when using an embedded initramfs can result in significant size differences in the resulting data. This is caused by avoiding double compression of the initramfs contents. For example on my tests, choosing CONFIG_INITRAMFS_COMPRESSION_NONE when compressing the kernel using XZ) results in up to 500KiB differences (9MiB to 8.5MiB) in the kernel size as the dictionary will not get polluted with uncomprensible data and may reuse kernel data too. Despite embedding an uncompressed initramfs, a user may want to allow for a compressed extra initramfs to be passed using the rd system, for example to boot a recovery system. 9ba4bcb645898d ("initramfs: read CONFIG_RD_ variables for initramfs compression") broke that behavior by making the choice based on CONFIG_RD_* instead of adding CONFIG_INITRAMFS_COMPRESSION_LZ4. Saddly, CONFIG_RD_* is also used to choose the supported RD compression algorithms by the kernel and a user may want to support more than one. This patch also reverts commit 3e4e0f0a875 ("initramfs: remove "compression mode" choice") restoring back the "compression mode" choice and includes the CONFIG_INITRAMFS_COMPRESSION_LZ4 option which was never added. As a result the following options are added or readed affecting the embedded initramfs compression: INITRAMFS_COMPRESSION_NONE Do no compression INITRAMFS_COMPRESSION_GZIP Compress using gzip INITRAMFS_COMPRESSION_BZIP2 Compress using bzip2 INITRAMFS_COMPRESSION_LZMA Compress using lzma INITRAMFS_COMPRESSION_XZ Compress using xz INITRAMFS_COMPRESSION_LZO Compress using lzo INITRAMFS_COMPRESSION_LZ4 Compress using lz4 These depend on the corresponding CONFIG_RD_* option being set (except NONE which has no dependencies). This patch depends on the previous one (the previous version didn't) to simplify the way in which the algorithm is chosen and keep backwards compatibility with the behaviour introduced by 9ba4bcb645898 ("initramfs: read CONFIG_RD_ variables for initramfs compression"). Link: http://lkml.kernel.org/r/57EAD77B.7090607@klondike.es Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <klondike@klondike.es> Cc: P J P <ppandit@redhat.com> Cc: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-14 15:06:04 -08:00