The BOOT_CONFIG family of Kconfig options allows a bootconfig file
containing kernel boot parameters to be embedded into an initrd or into
the kernel itself. This can be extremely useful when deploying kernels
in cases where some of the boot parameters depend on the kernel version
rather than on the server hardware, firmware, or workload.
Unfortunately, the "bootconfig" kernel parameter must be specified in
order to cause the kernel to look for the embedded bootconfig file,
and it clearly does not help to embed this "bootconfig" kernel parameter
into that file.
Therefore, provide a new BOOT_CONFIG_FORCE Kconfig option that causes the
kernel to act as if the "bootconfig" kernel parameter had been specified.
In other words, kernels built with CONFIG_BOOT_CONFIG_FORCE=y will look
for the embedded bootconfig file even when the "bootconfig" kernel
parameter is omitted. This permits kernel-version-dependent kernel
boot parameters to be embedded into the kernel image without the need to
(for example) update large numbers of boot loaders.
Link: https://lore.kernel.org/all/20230105005838.GA1772817@paulmck-ThinkPad-P17-Gen-1/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <linux-doc@vger.kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a description how to embed the bootconfig file into kernel.
Link: https://lkml.kernel.org/r/164921228987.1090670.16843569536974147213.stgit@devnote2
Cc: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add a section to describe how to use the bootconfig for
specifying kernel and init parameters. This is an important
section because it is the reason why this document is under
the admin-guide.
Link: https://lkml.kernel.org/r/163077086399.222577.5881779375643977991.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add a description about the endianness of the size and the checksum
fields. Those must be stored as le32 instead of u32. This will allow
us to apply bootconfig to the cross build initrd without caring
the endianness.
Link: https://lkml.kernel.org/r/160583936246.547349.10964204130590955409.stgit@devnote2
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
- Lots of RST conversion work by Mauro, Daniel ALmeida, and others.
Maybe someday we'll get to the end of this stuff...maybe...
- Some organizational work to bring some order to the core-api manual.
- Various new docs and additions to the existing documentation.
- Typo fixes, warning fixes, ...
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Merge tag 'docs-5.7' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"This has been a busy cycle for documentation work.
Highlights include:
- Lots of RST conversion work by Mauro, Daniel ALmeida, and others.
Maybe someday we'll get to the end of this stuff...maybe...
- Some organizational work to bring some order to the core-api
manual.
- Various new docs and additions to the existing documentation.
- Typo fixes, warning fixes, ..."
* tag 'docs-5.7' of git://git.lwn.net/linux: (123 commits)
Documentation: x86: exception-tables: document CONFIG_BUILDTIME_TABLE_SORT
MAINTAINERS: adjust to filesystem doc ReST conversion
docs: deprecated.rst: Add BUG()-family
doc: zh_CN: add translation for virtiofs
doc: zh_CN: index files in filesystems subdirectory
docs: locking: Drop :c:func: throughout
docs: locking: Add 'need' to hardirq section
docs: conf.py: avoid thousands of duplicate label warning on Sphinx
docs: prevent warnings due to autosectionlabel
docs: fix reference to core-api/namespaces.rst
docs: fix pointers to io-mapping.rst and io_ordering.rst files
Documentation: Better document the softlockup_panic sysctl
docs: hw-vuln: tsx_async_abort.rst: get rid of an unused ref
docs: perf: imx-ddr.rst: get rid of a warning
docs: filesystems: fuse.rst: supress a Sphinx warning
docs: translations: it: avoid duplicate refs at programming-language.rst
docs: driver.rst: supress two ReSt warnings
docs: trace: events.rst: convert some new stuff to ReST format
Documentation: Add io_ordering.rst to driver-api manual
Documentation: Add io-mapping.rst to driver-api manual
...
Add append value operator "+=" support to bootconfig syntax.
With this operator, user can add new value to the key as
an entry of array instead of overwriting.
For example,
foo = bar
...
foo += baz
Then the key "foo" has "bar" and "baz" values as an array.
Link: http://lkml.kernel.org/r/158227283195.12842.8310503105963275584.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Currently, bootconfig adds a new value on the existing key to the tail of an
array. But this looks a bit confusing because an admin can easily rewrite
the original value in the same config file.
This rejects the following value re-definition.
key = value1
...
key = value2
You should rewrite value1 to value2 in this case.
Link: http://lkml.kernel.org/r/158227282199.12842.10110929876059658601.stgit@devnote2
Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ Fixed spelling of arraies to arrays ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reject if a value node is mixed with subkey node on same
parent key node.
A value node can not co-exist with subkey node under some key
node, e.g.
key = value
key.subkey = another-value
This is not be allowed because bootconfig API is not designed
to handle such case.
Link: http://lkml.kernel.org/r/158220115232.26565.7792340045009731803.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add bootconfig magic word to the end of bootconfig on initrd
image for indicating explicitly the bootconfig is there.
Also tools/bootconfig treats wrong size or wrong checksum or
parse error as an error, because if there is a bootconfig magic
word, there must be a bootconfig.
The bootconfig magic word is "#BOOTCONFIG\n", 12 bytes word.
Thus the block image of the initrd file with bootconfig is
as follows.
[Initrd][bootconfig][size][csum][#BOOTCONFIG\n]
Link: http://lkml.kernel.org/r/158220112263.26565.3944814205960612841.stgit@devnote2
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
As the bootconfig is appended to the initrd it is not as easy to modify as
the kernel command line. If there's some issue with the kernel, and the
developer wants to boot a pristine kernel, it should not be needed to modify
the initrd to remove the bootconfig for a single boot.
As bootconfig is silently added (if the admin does not know where to look
they may not know it's being loaded). It should be explicitly added to the
kernel cmdline. The loading of the bootconfig is only done if "bootconfig"
is on the kernel command line. This will let admins know that the kernel
command line is extended.
Note, after adding printk()s for when the size is too great or the checksum
is wrong, exposed that the current method always looked for the boot config,
and if this size and checksum matched, it would parse it (as if either is
wrong a printk has been added to show this). It's better to only check this
if the boot config is asked to be looked for.
Link: https://lore.kernel.org/r/CAHk-=wjfjO+h6bQzrTf=YCZA53Y3EDyAs3Z4gEsT7icA3u_Psw@mail.gmail.com
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fix typos in bootconfig.rst according to Randy's suggestions.
Link: http://lkml.kernel.org/r/157949059219.25888.16939971423610233631.stgit@devnote2
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add a documentation for extended boot config under
admin-guide, since it is including the syntax of boot config.
Link: http://lkml.kernel.org/r/157867230658.17873.9309879174829924324.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Paul E. McKenney