One user has expressed the need to both append and prepend some
built-in parameters to the command line provided by the bootloader.

Allthough it is a corner case, it is easy to implement so let's do it.

When the user chooses to prepend the bootloader provided command line
with the built-in command line, he is offered the possibility to enter
an additionnal built-in command line to be appended after the
bootloader provided command line.

It is a complementary feature which has no impact on the already
existing ones and/or the existing defconfig.

Suggested-by: Daniel Walker <danie...@cisco.com>
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
Sending this out as an RFC, applies on top of the series
("Implement GENERIC_CMDLINE"). I will add it to the series next spin
unless someone is against it.
---
 include/linux/cmdline.h |  3 +++
 init/Kconfig            | 12 +++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h
index 020028e2bdf0..fb274a4d5519 100644
--- a/include/linux/cmdline.h
+++ b/include/linux/cmdline.h
@@ -36,6 +36,9 @@ static __always_inline bool __cmdline_build(char *dst, const 
char *src)
 
        len = cmdline_strlcat(dst, src, COMMAND_LINE_SIZE);
 
+       if (IS_ENABLED(CONFIG_CMDLINE_PREPEND))
+               len = cmdline_strlcat(dst, " " CONFIG_CMDLINE_MORE, 
COMMAND_LINE_SIZE);
+
        if (IS_ENABLED(CONFIG_CMDLINE_APPEND))
                len = cmdline_strlcat(dst, " " CONFIG_CMDLINE, 
COMMAND_LINE_SIZE);
 
diff --git a/init/Kconfig b/init/Kconfig
index fa002e3765ab..cd3087ff4f28 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -128,6 +128,14 @@ config CMDLINE
          If this string is not empty, additional choices are proposed
          below to determine how it will be used by the kernel.
 
+config CMDLINE_MORE
+       string "Additional default kernel command string" if GENERIC_CMDLINE && 
CMDLINE_PREPEND
+       default ""
+       help
+         Defines an additional default kernel command string.
+         If this string is not empty, it is appended to the
+         command-line arguments provided by the bootloader
+
 choice
        prompt "Kernel command line type" if CMDLINE != ""
        default CMDLINE_PREPEND if ARCH_WANT_CMDLINE_PREPEND_BY_DEFAULT
@@ -154,7 +162,9 @@ config CMDLINE_PREPEND
        bool "Prepend to the bootloader kernel arguments"
        help
          The default kernel command string will be prepended to the
-         command-line arguments provided by the bootloader.
+         command-line arguments provided by the bootloader. When this
+         option is selected, another string can be added which will
+         be appended.
 
 config CMDLINE_FORCE
        bool "Always use the default kernel command string"
-- 
2.25.0

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