kernel/linux.git/usr/Kconfig, branch v6.6.132

initramfs: Remove redundant dependency of RD_ZSTD on BLK_DEV_INITRD

2021-02-24T06:12:06+00:00

Commit be1859bdc660 ("initramfs: remove redundant dependency on BLK_DEV_INITRD") removed all redundant dependencies on BLK_DEV_INITRD, but the recent addition of zstd support introduced a new one. Fixes: a30d8a39f057 ("usr: Add support for zstd compressed initramfs") Signed-off-by: Geert Uytterhoeven Signed-off-by: Masahiro Yamada

usr: Add support for zstd compressed initramfs

2020-07-31T09:49:08+00:00

- Add support for a zstd compressed initramfs. - Add compression for compressing built-in initramfs with zstd. I have tested this patch by boot testing with buildroot and QEMU. Specifically, I booted the kernel with both a zstd and gzip compressed initramfs, both built into the kernel and separate. I ensured that the correct compression algorithm was used. I tested on arm, aarch64, i386, and x86_64. This patch has been tested in production on aarch64 and x86_64 devices. Additionally, I have performance measurements from internal use in production. On an aarch64 device we saw 19 second boot time improvement from switching from lzma to zstd (27 seconds to 8 seconds). On an x86_64 device we saw a 9 second boot time reduction from switching from xz to zstd. Signed-off-by: Nick Terrell Signed-off-by: Ingo Molnar Tested-by: Sedat Dilek Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20200730190841.2071656-5-nickrterrell@gmail.com

initramfs: restore default compression behavior

2020-03-17T00:50:37+00:00

Even though INITRAMFS_SOURCE kconfig option isn't set in most of defconfigs it is used (set) extensively by various build systems. Commit f26661e12765 ("initramfs: make initramfs compression choice non-optional") has changed default compression mode. Previously we compress initramfs using available compression algorithm. Now we don't use any compression at all by default. It significantly increases the image size in case of build system chooses embedded initramfs. Initially I faced with this issue while using buildroot. As of today it's not possible to set preferred compression mode in target defconfig as this option depends on INITRAMFS_SOURCE being set. Modification of all build systems either doesn't look like good option. Let's instead rewrite initramfs compression mode choices list the way that "INITRAMFS_COMPRESSION_NONE" will be the last option in the list. In that case it will be chosen only if all other options (which implements any compression) are not available. Signed-off-by: Eugeniy Paltsev Signed-off-by: Masahiro Yamada

initramfs: do not show compression mode choice if INITRAMFS_SOURCE is empty

2020-02-03T17:31:43+00:00

Since commit ddd09bcc899f ("initramfs: make compression options not depend on INITRAMFS_SOURCE"), Kconfig asks the compression mode for the built-in initramfs regardless of INITRAMFS_SOURCE. It is technically simpler, but pointless from a UI perspective, Linus says [1]. When INITRAMFS_SOURCE is empty, usr/Makefile creates a tiny default cpio, which is so small that nobody cares about the compression. This commit hides the Kconfig choice in that case. The default cpio is embedded without compression, which was the original behavior. [1]: https://lkml.org/lkml/2020/2/1/160 Suggested-by: Linus Torvalds Signed-off-by: Masahiro Yamada Signed-off-by: Linus Torvalds

initramfs: refactor the initramfs build rules

2020-01-15T15:26:21+00:00

Currently, usr/gen_initramfs.sh takes care of all the use-cases: [1] generates a cpio file unless CONFIG_INITRAMFS_SOURCE points to a single cpio archive [2] If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive, use it as-is. [3] Compress the cpio file according to CONFIG_INITRAMFS_COMPRESSION_* unless it is passed a compressed archive. To simplify the script, move [2] and [3] to usr/Makefile. If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive, there is no need to run this shell script. For the cpio archive compression, you can re-use the rules from scripts/Makefile.lib . Signed-off-by: Masahiro Yamada

initramfs: make initramfs compression choice non-optional

2020-01-14T01:42:44+00:00

Currently, the choice of the initramfs compression mode is too complex because users are allowed to not specify the compression mode at all. I think it makes more sense to require users to choose the compression mode explicitly, and delete the fallback defaults of INITRAMFS_COMPRESSION. Signed-off-by: Masahiro Yamada

initramfs: make compression options not depend on INITRAMFS_SOURCE

2020-01-14T01:42:44+00:00

Even if INITRAMFS_SOURCE is empty, usr/gen_initramfs.sh generates a tiny default initramfs, which is embedded in vmlinux. So, defining INITRAMFS_COMPRESSION* options should be valid irrespective of INITRAMFS_SOURCE. Signed-off-by: Masahiro Yamada

initramfs: remove redundant dependency on BLK_DEV_INITRD

2020-01-14T01:42:44+00:00

init/Kconfig includes usr/Kconfig inside the "if BLK_DEV_INITRD" ... "endif" block: if BLK_DEV_INITRD source "usr/Kconfig" endif Hence, all the defines in usr/Kconfig depend on BLK_DEV_INITRD. Remove the redundant "depends on BLK_DEV_INITRD". Signed-off-by: Masahiro Yamada Reviewed-by: Greg Thelen

docs: early-userspace: move to driver-api guide

2019-07-15T14:03:01+00:00

Those documents describe a kAPI. So, add to the driver-api book. Signed-off-by: Mauro Carvalho Chehab

docs: early-userspace: convert docs to ReST and rename to *.rst

2019-07-15T12:20:23+00:00

The two files there describes a Kernel API feature, used to support early userspace stuff. Prepare for moving them to the kernel API book by converting to ReST format. The conversion itself was quite trivial: just add/mark a few titles as such, add a literal block markup, add a table markup and a few blank lines, in order to make Sphinx to properly parse it. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab