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 <[email protected]> --- Changes in v2 (addressing review of v1): - Split out a standalone fix for the NULL-pointer arithmetic in xbc_snprint_cmdline() so the build-time render cannot trip host UBSan/FORTIFY_SOURCE. - Rework the leaf-root handling: instead of returning early, skip @root inside the loop so a root carrying both a value and subkeys (kernel = x together with kernel.foo = bar) still renders its descendant keys. - Build tools/bootconfig with $(HOSTCC) so cross-compiled (ARCH=...) builds render the cmdline on the build host instead of failing with "Exec format error". - Mark the embedded cmdline section read-only (drop the "w" flag from .init.rodata). - Add a make-clean hook so tools/bootconfig artifacts are removed by make clean. - Gate the x86 prepend on "bootconfig" being present on the command line (or CONFIG_BOOT_CONFIG_FORCE), matching the init.* opt-in semantics documented in bootconfig.rst and preserving fail-safe recovery: dropping "bootconfig" from the bootloader cmdline now also disables the embedded kernel.* keys. - Link to v1: https://patch.msgid.link/[email protected] --- Breno Leitao (6): bootconfig: fix NULL-pointer arithmetic in xbc_snprint_cmdline() bootconfig: render descendant keys when xbc_snprint_cmdline() root has a value bootconfig: render embedded bootconfig as a kernel cmdline at build time bootconfig: clean build-time tools/bootconfig from make clean bootconfig: add xbc_prepend_embedded_cmdline() helper x86/setup: prepend embedded bootconfig cmdline before parse_early_param MAINTAINERS | 1 + Makefile | 18 +++++++- arch/x86/Kconfig | 1 + arch/x86/kernel/setup.c | 16 +++++++ include/linux/bootconfig.h | 9 ++++ init/Kconfig | 33 +++++++++++++ init/main.c | 18 ++++++-- lib/Makefile | 16 +++++++ lib/bootconfig.c | 112 ++++++++++++++++++++++++++++++++++++++++++--- lib/embedded-cmdline.S | 16 +++++++ tools/bootconfig/Makefile | 10 ++-- 11 files changed, 236 insertions(+), 14 deletions(-) --- base-commit: e7e28506af98ce4e1059e5ec59334b335c00a246 change-id: 20260508-bootconfig_using_tools-cfa7aa9d6a5a Best regards, -- Breno Leitao <[email protected]>
