On Mon, Mar 28, 2022 at 7:29 AM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > KNOWN ISSUE: > > According to the report from Padmanabha[3] and my analysis [4], the embedded > bootconfig data may not be updated if you do incremental build the kernel > with CONFIG_LTO_CLANG_THIN. > > [3] https://lore.kernel.org/all/20220321183500.GA4065@pswork/T/#u > [4] https://lore.kernel.org/all/20220327115526.cc4b0ff55fc53c97683c3e4d@xxxxxxxxxx/ > > This seems like clang's LTO Thin mode issue. It may not detect the inline > asm depends on external files. > > I think the possible workaround is to split the inline asm which includes > '.incbin' directive into an asm file. But this should be done in another > seires because there are other features which uses '.incbin'. (e.g. > /proc/config.gz) Hi Masami, I saw Padmanabha's report (thanks for the report); sorry for not responding sooner, I've been traveling recently for a funeral. Any chance we can use CFLAGS_REMOVE_<file>.o := $(CC_FLAGS_LTO) a la commit d2dcd3e37475 ("x86, cpu: disable LTO for cpu.c") with a comment linking to https://github.com/ClangBuiltLinux/linux/issues/1618 for the Translation Units using .incbin, until we have had more time to triage+fix? -- Thanks, ~Nick Desaulniers
