linux.git/Documentation/admin-guide/bootconfig.rst, branch v5.6

bootconfig: Add append value operator support

2020-02-21T14:59:39+00:00

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 
Signed-off-by: Steven Rostedt (VMware)

bootconfig: Prohibit re-defining value on same key

2020-02-21T14:59:19+00:00

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) 
Signed-off-by: Masami Hiramatsu 
[ Fixed spelling of arraies to arrays ]
Signed-off-by: Steven Rostedt (VMware)

bootconfig: Reject subkey and value on same parent key

2020-02-20T22:54:09+00:00

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 
Signed-off-by: Steven Rostedt (VMware)

bootconfig: Add bootconfig magic word for indicating bootconfig explicitly

2020-02-20T22:52:34+00:00

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 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

bootconfig: Only load bootconfig if "bootconfig" is on the kernel cmdline

2020-02-05T09:22:43+00:00

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 
Suggested-by: Linus Torvalds 
Signed-off-by: Steven Rostedt (VMware)

Documentation: bootconfig: Fix typos in bootconfig documentation

2020-01-21T23:24:52+00:00

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 
Acked-by: Randy Dunlap 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

Documentation: tracing: Add boot-time tracing document

2020-01-13T18:19:42+00:00

Add a documentation about boot-time tracing options in
boot config.

Link: http://lkml.kernel.org/r/157867246028.17873.8047384554383977870.stgit@devnote2

Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

Documentation: bootconfig: Add a doc for extended boot config

2020-01-13T18:19:40+00:00

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 
Signed-off-by: Steven Rostedt (VMware)