On Mon, 08 Jun 2026 09:23:57 -0700 Breno Leitao <[email protected]> wrote:
> 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. > Sashiko still leaves some comments. https://sashiko.dev/#/patchset/20260608-bootconfig_using_tools-v3-0-4ddd079a0696%40debian.org BTW, can you also update the document (Documentation/admin-guide/bootconfig.rst) about what is the expected behavior of this feature (kconfigs, examples)? Thank you, > Signed-off-by: Breno Leitao <[email protected]> > --- > Changes in v3: > - Patch 3: Move HOSTCC override to the kernel-side rule; tool keeps > $(CC) for standalone/cross builds. > - Patch 6: Drop the false fail-safe wording; document the > BOOT_CONFIG_FORCE=y default interaction. > - Link to v2: > > https://lore.kernel.org/r/[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 | 24 +++++++++- > arch/x86/Kconfig | 1 + > arch/x86/kernel/setup.c | 16 +++++++ > include/linux/bootconfig.h | 9 ++++ > init/Kconfig | 36 +++++++++++++++ > init/main.c | 25 ++++++++-- > lib/Makefile | 16 +++++++ > lib/bootconfig.c | 112 > ++++++++++++++++++++++++++++++++++++++++++--- > lib/embedded-cmdline.S | 16 +++++++ > tools/bootconfig/Makefile | 4 +- > 11 files changed, 247 insertions(+), 13 deletions(-) > --- > base-commit: e7e28506af98ce4e1059e5ec59334b335c00a246 > change-id: 20260508-bootconfig_using_tools-cfa7aa9d6a5a > > Best regards, > -- > Breno Leitao <[email protected]> > -- Masami Hiramatsu (Google) <[email protected]>
