Commit 10e68b02c861 ("Makefile: support compressed debug info") added support for compressed debug sections. Support is detected by checking - does the compiler support -gz=zlib - does the assembler support --compressed-debug-sections=zlib - does the linker support --compressed-debug-sections=zlib However, the gcc driver's support for this option is somewhat convoluted. The driver's builtin specs are set based on the version of binutils that it was configured with. It reports an error if the configure-time linker/assembler (i.e., not necessarily the actual assembler that will be run) do not support the option, but only if the assembler (or linker) is actually invoked when -gz=zlib is passed. The cc-option check in scripts/Kconfig.include does not invoke the assembler, so the gcc driver reports success even if it does not support the option being passed to the assembler. Because the as-option check passes the option directly to the assembler via -Wa,--compressed-debug-sections=zlib, the gcc driver does not see this option and will never report an error.

Combined with an installed version of binutils that is more recent than the one the compiler was built with, it is possible for all three tests to succeed, yet an actual compilation with -gz=zlib to fail. Moreover, it is unnecessary to explicitly pass --compressed-debug-sections=zlib to the assembler via -Wa, since the driver will do that automatically when it supports -gz=zlib. Convert the as-option to just -gz=zlib, simplifying it as well as performing a better test of the gcc driver's capabilities. Reported-by: kernel test robot <lkp(a)intel.com&gt; Signed-off-by: Arvind Sankar <nivedita(a)alum.mit.edu&gt; --- Makefile | 2 +- lib/Kconfig.debug | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 839f9fee22cb..cb29e56f227a 100644 --- a/Makefile +++ b/Makefile @@ -842,7 +842,7 @@ endif ifdef CONFIG_DEBUG_INFO_COMPRESSED DEBUG_CFLAGS += -gz=zlib -KBUILD_AFLAGS += -Wa,--compress-debug-sections=zlib +KBUILD_AFLAGS += -gz=zlib KBUILD_LDFLAGS += --compress-debug-sections=zlib endif diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index cb98741601bd..94ce36be470c 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -229,7 +229,7 @@ config DEBUG_INFO_COMPRESSED bool "Compressed debugging information" depends on DEBUG_INFO depends on $(cc-option,-gz=zlib) - depends on $(as-option,-Wa$(comma)--compress-debug-sections=zlib) + depends on $(as-option,-gz=zlib) depends on $(ld-option,--compress-debug-sections=zlib) help Compress the debug information using zlib. Requires GCC 5.0+ or Clang -- 2.26.2