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Masahiro Yamada 7ce7e984ab kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22}
GZIP-compressed files end with 4 byte data that represents the size
of the original input. The decompressors (the self-extracting kernel)
exploit it to know the vmlinux size beforehand. To mimic the GZIP's
trailer, Kbuild provides cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22}.
Unfortunately these macros are used everywhere despite the appended
size data is only useful for the decompressors.

There is no guarantee that such hand-crafted trailers are safely ignored.
In fact, the kernel refuses compressed initramdfs with the garbage data.
That is why usr/Makefile overrides size_append to make it no-op.

To limit the use of such broken compressed files, this commit renames
the existing macros as follows:

  cmd_bzip2   --> cmd_bzip2_with_size
  cmd_lzma    --> cmd_lzma_with_size
  cmd_lzo     --> cmd_lzo_with_size
  cmd_lz4     --> cmd_lz4_with_size
  cmd_xzkern  --> cmd_xzkern_with_size
  cmd_zstd22  --> cmd_zstd22_with_size

To keep the decompressors working, I updated the following Makefiles
accordingly:

  arch/arm/boot/compressed/Makefile
  arch/h8300/boot/compressed/Makefile
  arch/mips/boot/compressed/Makefile
  arch/parisc/boot/compressed/Makefile
  arch/s390/boot/compressed/Makefile
  arch/sh/boot/compressed/Makefile
  arch/x86/boot/compressed/Makefile

I reused the current macro names for the normal usecases; they produce
the compressed data in the proper format.

I did not touch the following:

  arch/arc/boot/Makefile
  arch/arm64/boot/Makefile
  arch/csky/boot/Makefile
  arch/mips/boot/Makefile
  arch/riscv/boot/Makefile
  arch/sh/boot/Makefile
  kernel/Makefile

This means those Makefiles will stop appending the size data.

I dropped the 'override size_append' hack from usr/Makefile.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
2022-01-14 02:54:05 +09:00
arch kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22} 2022-01-14 02:54:05 +09:00
block block: call rq_qos_done() before ref check in batch completions 2021-11-26 09:53:23 -07:00
certs certs: move scripts/extract-cert to certs/ 2022-01-08 18:28:21 +09:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation doc: kbuild: fix default in imply table 2022-01-08 18:28:21 +09:00
drivers kbuild: do not quote string values in include/config/auto.conf 2022-01-08 18:03:57 +09:00
fs 5 ksmbd server fixes, 4 for stable 2021-11-27 14:49:35 -08:00
include kbuild: move headers_check.pl to usr/include/ 2022-01-08 17:41:00 +09:00
init kbuild: do not quote string values in include/config/auto.conf 2022-01-08 18:03:57 +09:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel gcov: Remove compiler version check 2021-12-02 17:25:21 +09:00
lib parisc: Increase FRAME_WARN to 2048 bytes on parisc 2021-11-22 07:37:31 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Fixes for 5.16 folios: 2021-11-25 10:13:56 -08:00
net kbuild: do not quote string values in include/config/auto.conf 2022-01-08 18:03:57 +09:00
samples s390 updates for 5.16-rc2 2021-11-20 10:55:50 -08:00
scripts kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22} 2022-01-14 02:54:05 +09:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound xen: branch for v5.16-rc3 2021-11-26 09:54:13 -08:00
tools Networking fixes for 5.16-rc3, including fixes from netfilter. 2021-11-26 12:58:53 -08:00
usr kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22} 2022-01-14 02:54:05 +09:00
virt Merge branch 'kvm-5.16-fixes' into kvm-master 2021-11-18 02:11:57 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS certs: move scripts/extract-cert to certs/ 2022-01-08 18:28:21 +09:00
Makefile kbuild: do not quote string values in include/config/auto.conf 2022-01-08 18:03:57 +09:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.