On Wed, May 22, 2024 at 4:48 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > CONFIG_DEBUG_INFO_BTF=y requires one additional link step. > (.tmp_vmlinux.btf) > > CONFIG_KALLSYMS=y requires two additional link steps. > (.tmp_vmlinux.kallsyms1 and .tmp_vmlinux.kallsyms2) > > Enabling both requires three additional link steps. > > When CONFIG_DEBUG_INFO_BTF=y and CONFIG_KALLSYMS=y, the build step looks > as follows: > > KSYMS .tmp_vmlinux.kallsyms0.S > AS .tmp_vmlinux.kallsyms0.o > LD .tmp_vmlinux.btf # temp vmlinux for BTF > BTF .btf.vmlinux.bin.o > LD .tmp_vmlinux.kallsyms1 # temp vmlinux for kallsyms step 1 > NM .tmp_vmlinux.kallsyms1.syms > KSYMS .tmp_vmlinux.kallsyms1.S > AS .tmp_vmlinux.kallsyms1.o > LD .tmp_vmlinux.kallsyms2 # temp vmlinux for kallsyms step 2 > NM .tmp_vmlinux.kallsyms2.syms > KSYMS .tmp_vmlinux.kallsyms2.S > AS .tmp_vmlinux.kallsyms2.o > LD vmlinux # final vmlinux > > This is redundant because the BTF generation and the kallsyms step 1 can > be performed against the same temporary vmlinux. > > When both CONFIG_DEBUG_INFO_BTF and CONFIG_KALLSYMS are enabled, we can > reduce the number of link steps. > > The build step will look as follows: > > KSYMS .tmp_vmlinux0.kallsyms.S > AS .tmp_vmlinux0.kallsyms.o > LD .tmp_vmlinux1 # temp vmlinux for BTF and kallsyms step 1 > BTF .tmp_vmlinux1.btf.o > NM .tmp_vmlinux1.syms > KSYMS .tmp_vmlinux1.kallsyms.S > AS .tmp_vmlinux1.kallsyms.o > LD .tmp_vmlinux2 # temp vmlinux for kallsyms step 2 > NM .tmp_vmlinux2.syms > KSYMS .tmp_vmlinux2.kallsyms.S > AS .tmp_vmlinux2.kallsyms.o > LD vmlinux # final link > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- > LGTM, thanks! Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > scripts/link-vmlinux.sh | 45 +++++++++++++++++++++-------------------- > 1 file changed, 23 insertions(+), 22 deletions(-) > [...]
