Commit db2aa7fd ("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 db2aa7fd ("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 9e3596b0 ("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: db2aa7fd ("initramfs: allow again choice of the embedded initram compression algorithm")
Fixes: 9e3596b0 ("kbuild: initramfs cleanup, set target from Kconfig")
Link: http://lkml.kernel.org/r/20170521033337.6197-1-f.fainelli@gmail.comSigned-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Acked-by: NNicholas 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Many "embedded" architectures provide CMDLINE_FORCE to allow the kernel
to override the command line provided by an inflexible bootloader.
However there is currrently no way for the kernel to override the
initramfs image provided by the bootloader meaning there are still ways
for bootloaders to make things difficult for us.

Fix this by introducing INITRAMFS_FORCE which can prevent the kernel
from loading the bootloader supplied image.

We use CMDLINE_FORCE (and its friend CMDLINE_EXTEND) to imply that the
system has an inflexible bootloader.  This allow us to avoid presenting
this config option to users of systems where inflexible bootloaders
aren't usually a problem.

Link: http://lkml.kernel.org/r/20170217121940.30126-1-daniel.thompson@linaro.orgSigned-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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.  9ba4bcb6 ("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 3e4e0f0a ("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 9ba4bcb6
("initramfs: read CONFIG_RD_ variables for initramfs compression").

Link: http://lkml.kernel.org/r/57EAD77B.7090607@klondike.esSigned-off-by: NFrancisco Blas Izquierdo Riera (klondike) <klondike@klondike.es>
Cc: P J P <ppandit@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the current builtin initram compression algorithm selection from
the Makefile into the INITRAMFS_COMPRESSION variable.  This makes
deciding algorithm precedence easier and would allow for overrides if
new algorithms want to be tested.

Link: http://lkml.kernel.org/r/57EAD769.1090401@klondike.esSigned-off-by: NFrancisco Blas Izquierdo Riera (klondike) <klondike@klondike.es>
Cc: P J P <ppandit@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The kernel has support for (nearly) every compression algorithm known to
man, each to handle some particular microscopic niche.

Unfortunately all of these always get compiled in if you want to support
INITRDs, and can be only disabled when CONFIG_EXPERT is set.

I don't see why I need to set EXPERT just to properly configure the initrd
compression algorithms, and not always include every possible algorithm

Usually the initrd is just compressed with gzip anyways, at least that's
true on all distributions I use.

Remove the dependencies for initrd compression on CONFIG_EXPERT.

Make the various options just default y, which should be good enough to
not break any previous configuration.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 9ba4bcb6 ("initramfs: read CONFIG_RD_ variables for initramfs
compression") removed the users of the various INITRAMFS_COMPRESSION_*
Kconfig symbols.  So since v3.13 the entire "Built-in initramfs
compression mode" choice is a set of knobs connected to nothing.  The
entire choice can safely be removed.
Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Cc: P J P <ppandit@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add support for extracting LZ4-compressed kernel images, as well as
LZ4-compressed ramdisk images in the kernel boot process.
Signed-off-by: NKyungsik Lee <kyungsik.lee@lge.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There have been new compression algorithms added without updating nearby
relevant descriptive text that refers to (a) the number of compression
algorithms and (b) the most recent one.  Fix these inconsistencies.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Reported-by: <qasdfgtyuiop@gmail.com>
Cc: Lasse Collin <lasse.collin@tukaani.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Alain Knaff <alain@knaff.lu>
Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option
is used to configure any non-standard kernel with a much larger scope than
only small devices.

This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes
references to the option throughout the kernel.  A new CONFIG_EMBEDDED
option is added that automatically selects CONFIG_EXPERT when enabled and
can be used in the future to isolate options that should only be
considered for embedded systems (RISC architectures, SLOB, etc).

Calling the option "EXPERT" more accurately represents its intention: only
expert users who understand the impact of the configuration changes they
are making should enable it.
Reviewed-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NDavid Woodhouse <david.woodhouse@intel.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Greg KH <gregkh@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This implements the API defined in <linux/decompress/generic.h> which is
used for kernel, initramfs, and initrd decompression.  This patch together
with the first patch is enough for XZ-compressed initramfs and initrd;
XZ-compressed kernel will need arch-specific changes.

The buffering requirements described in decompress_unxz.c are stricter
than with gzip, so the relevant changes should be done to the
arch-specific code when adding support for XZ-compressed kernel.
Similarly, the heap size in arch-specific pre-boot code may need to be
increased (30 KiB is enough).

The XZ decompressor needs memmove(), memeq() (memcmp() == 0), and
memzero() (memset(ptr, 0, size)), which aren't available in all
arch-specific pre-boot environments.  I'm including simple versions in
decompress_unxz.c, but a cleaner solution would naturally be nicer.
Signed-off-by: NLasse Collin <lasse.collin@tukaani.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alain Knaff <alain@knaff.lu>
Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Phillip Lougher <phillip@lougher.demon.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Deleted a word which apeared twice.
Signed-off-by: NStephan Sperber <sperberstephan@googlemail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Signed-off-by: NAlbin Tonnerre <albin.tonnerre@free-electrons.com>
Tested-by: NWu Zhangjin <wuzhangjin@gmail.com>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: NRussell King <rmk@arm.linux.org.uk>
Acked-by: NRussell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: quiet Kconfig warning

It appears that Kconfig simply has no way to provide defaults for
entries that exist inside a conditionalized choice block.
Fortunately, it turns out we don't actually ever use
CONFIG_INITRAMFS_COMPRESSION_NONE, so we can just drop it for
everything outside the choice block.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

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: NH. Peter Anvin <hpa@zytor.com>

Impact: message formatting

Consistently spell LZMA in all capitals, since it (unlike gzip or
bzip2) is an acronym.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Impact: Kconfig clarification

Make it clear that the CONFIG_RD_* options are about what formats are
supported, not about what formats are actually being used.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Impact: reduce Kconfig noise

Move the options that control possible initramfs/initrd compressions
underneath CONFIG_EMBEDDED.  The only impact of leaving these options
set to y is additional code in the init section of the kernel; there
is no reason to burden non-embedded users with these options.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Impact: Avoids silent environment dependency

Make builtin initramfs compression an explicit configurable.  The
previous version would pick a compression based on the binaries which
were installed on the system, which could lead to unexpected results.
It is now explicitly configured, and not having the appropriate
binaries installed on the build host is simply an error.
Signed-off-by: NAlain Knaff <alain@knaff.lu>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Impact: Partial resolution of build failure

Move the initrd/initramfs configuration options from
drivers/block/Kconfig to usr/Kconfig, since they do not and should not
depend on CONFIG_BLK_DEV.  This fixes builds when CONFIG_BLK_DEV=n.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: Alexander E. Patrakov
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

Move initramfs options from Device Drivers | Block Drivers to General Setup
This is a more natural place for this option.

Furthermore separate out intramfs options to usr/Kconfig
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>