From 654102df2ac2a0d02a416100c3d44ff1dae932ca Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 23 Sep 2024 16:56:03 +0900 Subject: kbuild: add generic support for built-in boot DTBs Some architectures embed boot DTBs in vmlinux. A potential issue for these architectures is a race condition during parallel builds because Kbuild descends into arch/*/boot/dts/ twice. One build thread is initiated by the 'dtbs' target, which is a prerequisite of the 'all' target in the top-level Makefile: ifdef CONFIG_OF_EARLY_FLATTREE all: dtbs endif For architectures that support the built-in boot dtb, arch/*/boot/dts/ is visited also during the ordinary directory traversal in order to build obj-y objects that wrap DTBs. Since these build threads are unaware of each other, they can run simultaneously during parallel builds. This commit introduces a generic build rule to scripts/Makefile.vmlinux to support embedded boot DTBs in a race-free way. Architectures that want to use this rule need to select CONFIG_GENERIC_BUILTIN_DTB. After the migration, Makefiles under arch/*/boot/dts/ will be visited only once to build only *.dtb files. This change also aims to unify the CONFIG options used for built-in DTBs support. Currently, different architectures use different CONFIG options for the same purposes. With this commit, the CONFIG options will be unified as follows: - CONFIG_GENERIC_BUILTIN_DTB This enables the generic rule for built-in boot DTBs. This will be renamed to CONFIG_BUILTIN_DTB after all architectures migrate to the generic rule. - CONFIG_BUILTIN_DTB_NAME This specifies the path to the embedded DTB. (relative to arch/*/boot/dts/) - CONFIG_BUILTIN_DTB_ALL If this is enabled, all DTB files compiled under arch/*/boot/dts/ are embedded into vmlinux. Only used by MIPS. Signed-off-by: Masahiro Yamada --- scripts/link-vmlinux.sh | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'scripts/link-vmlinux.sh') diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index a9b3f34a78d2..53bd4b727e21 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -68,6 +68,10 @@ vmlinux_link() libs="${KBUILD_VMLINUX_LIBS}" fi + if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then + objs="${objs} .builtin-dtbs.o" + fi + if is_enabled CONFIG_MODULES; then objs="${objs} .vmlinux.export.o" fi -- cgit v1.3.1 From e6064da6461f989a357f2e280d7f8d4155267c4c Mon Sep 17 00:00:00 2001 From: Sedat Dilek Date: Tue, 26 Nov 2024 16:58:01 +0100 Subject: kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms Change the naming for consistency. While at this, fix the comments in scripts/link-vmlinux.sh. Signed-off-by: Sedat Dilek Signed-off-by: Masahiro Yamada --- scripts/link-vmlinux.sh | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'scripts/link-vmlinux.sh') diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 53bd4b727e21..139aa4d1215a 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -207,8 +207,8 @@ kallsymso= strip_debug= if is_enabled CONFIG_KALLSYMS; then - true > .tmp_vmlinux.kallsyms0.syms - kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms + true > .tmp_vmlinux0.syms + kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms fi if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then @@ -235,14 +235,14 @@ if is_enabled CONFIG_KALLSYMS; then # Generate section listing all symbols and add it into vmlinux # It's a four step process: # 0) Generate a dummy __kallsyms with empty symbol list. - # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, + # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, # with a dummy __kallsyms. - # Running kallsyms on that gives us .tmp_kallsyms1.o with + # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with # the right size - # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of + # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of # the right size, but due to the added section, some # addresses have shifted. - # From here, we generate a correct .tmp_vmlinux.kallsyms2.o + # From here, we generate a correct .tmp_vmlinux2.kallsyms.o # 3) That link may have expanded the kernel image enough that # more linker branch stubs / trampolines had to be added, which # introduces new names, which further expands kallsyms. Do another -- cgit v1.3.1