[PATCH 0/4] bootconfig: embed kernel.* cmdline at build time

[Breno Leitao]

The userspace pieces (xbc_snprint_cmdline() in lib/, tools/bootconfig -C)
already landed; this series wires the rendered cmdline into the kernel.

Motivation: today the embedded bootconfig is parsed at runtime, after
parse_early_param() has already run, so early_param() handlers can't
see embedded values. Folding the kernel.* subtree into the cmdline at
build time gives a CONFIG_CMDLINE-equivalent for embedded-bootconfig
users without forcing them to maintain two cmdline sources.

Behaviorally, the "kernel" subtree is rendered to a flat string at
build time and stashed in .init.rodata. setup_arch() prepends it to
boot_command_line before parse_early_param() runs. Overflow is a soft
error: the helper logs and leaves boot_command_line untouched rather
than panicking, so an oversized embedded bconf cannot brick a boot.

Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
---
Breno Leitao (4):
      bootconfig: return 0 from xbc_snprint_cmdline() for a leaf root
      bootconfig: render embedded bootconfig as a kernel cmdline at build time
      bootconfig: add xbc_prepend_embedded_cmdline() helper
      x86/setup: prepend embedded bootconfig cmdline before parse_early_param

 Makefile                   |  5 ++++
 arch/x86/Kconfig           |  1 +
 arch/x86/kernel/setup.c    |  3 +++
 include/linux/bootconfig.h |  7 ++++++
 init/Kconfig               | 33 ++++++++++++++++++++++++++
 init/main.c                | 19 ++++++++++++---
 lib/Makefile               | 16 +++++++++++++
 lib/bootconfig.c           | 58 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/embedded-cmdline.S     | 16 +++++++++++++
 tools/bootconfig/Makefile  |  2 +-
 10 files changed, 156 insertions(+), 4 deletions(-)
---
base-commit: e7e28506af98ce4e1059e5ec59334b335c00a246
change-id: 20260508-bootconfig_using_tools-cfa7aa9d6a5a

Best regards,
--  
Breno Leitao <leitao@xxxxxxxxxx>