diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | Makefile | 16 | ||||
| -rw-r--r-- | init/Kconfig | 36 | ||||
| -rw-r--r-- | lib/Makefile | 16 | ||||
| -rw-r--r-- | lib/embedded-cmdline.S | 16 | ||||
| -rw-r--r-- | tools/bootconfig/Makefile | 2 |
6 files changed, 86 insertions, 1 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 15011f5752a9..45adc7ea76dc 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9846,6 +9846,7 @@ F: fs/proc/bootconfig.c F: include/linux/bootconfig.h F: lib/bootconfig-data.S F: lib/bootconfig.c +F: lib/embedded-cmdline.S F: tools/bootconfig/* F: tools/bootconfig/scripts/* @@ -1552,6 +1552,22 @@ prepare: tools/bpf/resolve_btfids endif endif +# tools/bootconfig renders the embedded bootconfig into a cmdline at build time. +ifdef CONFIG_CMDLINE_FROM_BOOTCONFIG +prepare: tools/bootconfig +endif + +# tools/bootconfig is run on the build host during prepare, so force a host +# binary here; its own Makefile keeps $(CC) for standalone and cross builds. +# CROSS_COMPILE= is cleared so tools/scripts/Makefile.include does not inject +# the target's --target=/--sysroot= flags into the host clang invocation under +# LLVM=1 cross builds (which would produce a target binary that fails to exec). +tools/bootconfig: export CC := $(HOSTCC) +tools/bootconfig: FORCE + $(Q)mkdir -p $(objtree)/tools + $(Q)$(MAKE) O=$(abspath $(objtree)) subdir=tools -C $(srctree)/tools/ \ + bootconfig CROSS_COMPILE= + # The tools build system is not a part of Kbuild and tends to introduce # its own unique issues. If you need to integrate a new tool into Kbuild, # please consider locating that tool outside the tools/ tree and using the diff --git a/init/Kconfig b/init/Kconfig index 5230d4879b1c..598690ec313a 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1566,6 +1566,42 @@ config BOOT_CONFIG_EMBED_FILE This bootconfig will be used if there is no initrd or no other bootconfig in the initrd. +config ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG + bool + help + Silent symbol; no C code reads it directly. Architectures + select it once their setup_arch() calls + xbc_prepend_embedded_cmdline() before parse_early_param(). + Its only role is to gate the user-visible + CMDLINE_FROM_BOOTCONFIG option per-arch, the same + ARCH_SUPPORTS_* idiom used by ARCH_SUPPORTS_CFI, etc. + +config CMDLINE_FROM_BOOTCONFIG + bool "Render embedded bootconfig as kernel cmdline at build time" + depends on BOOT_CONFIG_EMBED_FILE != "" + depends on ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG + depends on CMDLINE = "" + default n + help + Render the "kernel" subtree of the embedded bootconfig file into a + flat cmdline string at kernel build time and prepend it to + boot_command_line during early architecture setup. This makes + early_param() handlers (e.g. mem=, earlycon=, loglevel=) see the + values supplied via the embedded bootconfig. + + The runtime bootconfig parser is unaffected, so tree-structured + consumers such as ftrace boot-time tracing keep working. + + Note: when an initrd also carries a bootconfig, its "kernel" + subtree is still parsed at runtime, but the embedded "kernel" + keys remain in boot_command_line for parse_early_param() and + end up later than the initrd keys in saved_command_line, so + parse_args() last-wins favors the embedded values. If you need + initrd to override embedded kernel.* keys, leave this option + off. + + If unsure, say N. + config CMDLINE_LOG_WRAP_IDEAL_LEN int "Length to try to wrap the cmdline when logged at boot" default 1021 diff --git a/lib/Makefile b/lib/Makefile index 7f75cc6edf94..4ccdce2fd5e5 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -273,6 +273,22 @@ filechk_defbconf = cat $(or $(real-prereqs), /dev/null) $(obj)/default.bconf: $(CONFIG_BOOT_CONFIG_EMBED_FILE) FORCE $(call filechk,defbconf) +obj-$(CONFIG_CMDLINE_FROM_BOOTCONFIG) += embedded-cmdline.o +$(obj)/embedded-cmdline.o: $(obj)/embedded_cmdline.bin + +# Render the bootconfig "kernel" subtree to a flat cmdline string using +# the userspace tools/bootconfig parser (-C mode). The runtime prepend +# helper enforces COMMAND_LINE_SIZE at boot, so no build-time size +# check is performed here (COMMAND_LINE_SIZE is an arch header +# constant, not a Kconfig value). +quiet_cmd_render_cmdline = BCONF2C $@ + cmd_render_cmdline = \ + $(objtree)/tools/bootconfig/bootconfig -C $< > $@ + +targets += embedded_cmdline.bin +$(obj)/embedded_cmdline.bin: $(obj)/default.bconf $(objtree)/tools/bootconfig/bootconfig FORCE + $(call if_changed,render_cmdline) + obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o diff --git a/lib/embedded-cmdline.S b/lib/embedded-cmdline.S new file mode 100644 index 000000000000..bda81b4a42be --- /dev/null +++ b/lib/embedded-cmdline.S @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Embed the build-time-rendered bootconfig "kernel" subtree as a flat + * cmdline string. setup_arch() prepends this to boot_command_line on + * architectures that select ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG. + * + * Copyright (c) 2026 Meta Platforms, Inc. and affiliates + * Copyright (c) 2026 Breno Leitao <leitao@debian.org> + */ + .section .init.rodata.embed_cmdline, "a", %progbits + .global embedded_kernel_cmdline +embedded_kernel_cmdline: + .incbin "lib/embedded_cmdline.bin" + .byte 0 + .global embedded_kernel_cmdline_end +embedded_kernel_cmdline_end: diff --git a/tools/bootconfig/Makefile b/tools/bootconfig/Makefile index 90eb47c9d8de..4e82fd9553cd 100644 --- a/tools/bootconfig/Makefile +++ b/tools/bootconfig/Makefile @@ -15,7 +15,7 @@ override CFLAGS += -Wall -g -I$(CURDIR)/include ALL_TARGETS := bootconfig ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS)) -all: $(ALL_PROGRAMS) test +all: $(ALL_PROGRAMS) $(OUTPUT)bootconfig: main.c include/linux/bootconfig.h $(LIBSRC) $(CC) $(filter %.c,$^) $(CFLAGS) $(LDFLAGS) -o $@ |