On Fri, 26 Jun 2026 05:50:09 -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. > Thanks for update!! This looks good to me. Let me pick it and test it. Thanks, > Signed-off-by: Breno Leitao <[email protected]> > --- > Changes in v7: > - The runtime opt-in now shares one helper instead of open-coding its > own. (Masami) > - bootconfig_cmdline_requested() moved into generic lib code (Masami) > - Link to v6: > https://lore.kernel.org/r/[email protected] > > Changes in v6: > - renamed CONFIG_BOOT_CONFIG_EMBED_CMDLINE to > CONFIG_CMDLINE_FROM_BOOTCONFIG > - prepend embedded bootconfig cmdline before parse_early_param > - Link to v5: > https://lore.kernel.org/r/[email protected] > > Changes in v5: > - Patch 3 (Kconfig): drop the redundant "depends on BOOT_CONFIG_EMBED" > from CMDLINE_FROM_BOOTCONFIG; Julian Braha. > - Patch 6 (Documentation): spell out how the embedded cmdline interacts > with the bootloader cmdline, an initrd bootconfig, and the embedded > bootconfig > - Link to v4: > https://lore.kernel.org/r/[email protected] > > Changes in v4: > - Patch 3 (build pipeline): clear CROSS_COMPILE= in the kernel-side > tools/bootconfig sub-make. Without it, an LLVM=1 cross build > inherits CROSS_COMPILE and tools/scripts/Makefile.include injects > --target=/--sysroot= into the host clang, producing a target > binary that fails to exec. > - Patch 3 (build pipeline): place embedded-cmdline.S in its own > .init.rodata.embed_cmdline subsection ("a") so ld.lld does not > see a section-type mismatch against lib/bootconfig-data.S's > writable .init.rodata ("aw"). The linker's *(.init.rodata > .init.rodata.*) glob still folds it into the init image. > - Patch 6 (x86/setup): also accept the bootconfig=<anything> form > via cmdline_find_option(), matching the runtime parse_args() loop. > Without it, bootconfig=0/=off would skip the early prepend but > still trigger the late runtime apply -- a split-brain state. > - New patch 7: document CONFIG_CMDLINE_FROM_BOOTCONFIG in > Documentation/admin-guide/bootconfig.rst (semantics, opt-in, > precedence, overflow behavior, example). > - Link to v3: > https://lore.kernel.org/r/[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 (9): > 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 > Documentation: bootconfig: document build-time cmdline rendering > x86/setup: prepend embedded bootconfig cmdline before parse_early_param > bootconfig: skip runtime kernel.* render once prepended early > init/main.c: use bootconfig_cmdline_requested() for the runtime opt-in > > Documentation/admin-guide/bootconfig.rst | 81 ++++++++++++++++ > MAINTAINERS | 1 + > Makefile | 27 +++++- > arch/x86/Kconfig | 1 + > arch/x86/kernel/setup.c | 14 ++- > include/linux/bootconfig.h | 14 +++ > init/Kconfig | 36 +++++++ > init/main.c | 52 +++++----- > lib/Makefile | 16 +++ > lib/bootconfig.c | 162 > +++++++++++++++++++++++++++++-- > lib/embedded-cmdline.S | 16 +++ > tools/bootconfig/Makefile | 4 +- > 12 files changed, 388 insertions(+), 36 deletions(-) > --- > base-commit: a87737435cfa134f9cdcc696ba3080759d04cf72 > change-id: 20260508-bootconfig_using_tools-cfa7aa9d6a5a > > Best regards, > -- > Breno Leitao <[email protected]> > -- Masami Hiramatsu (Google) <[email protected]>
