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authorMasahiro Yamada <masahiroy@kernel.org>2020-06-14 16:43:41 +0200
committerMasahiro Yamada <masahiroy@kernel.org>2020-06-17 03:38:42 +0200
commit4d0831e8a029c03f49f434f28b8faef9f0bd403f (patch)
treee092627794e9b75423b84dbf66b0221f862b6340 /lib
parentkbuild: improve cc-option to clean up all temporary files (diff)
downloadlinux-4d0831e8a029c03f49f434f28b8faef9f0bd403f.tar.xz
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kconfig: unify cc-option and as-option
cc-option and as-option are almost the same; both pass the flag to $(CC). The main difference is the cc-option stops before the assemble stage (-S option) whereas as-option stops after (-c option). I chose -S because it is slightly faster, but $(cc-option,-gz=zlib) returns a wrong result (https://lkml.org/lkml/2020/6/9/1529). It has been fixed by commit 7b16994437c7 ("Makefile: Improve compressed debug info support detection"), but the assembler should always be invoked for more reliable compiler option tests. However, you cannot simply replace -S with -c because the following code in lib/Kconfig.debug would break: depends on $(cc-option,-gsplit-dwarf) The combination of -c and -gsplit-dwarf does not accept /dev/null as output. $ cat /dev/null | gcc -gsplit-dwarf -S -x c - -o /dev/null $ echo $? 0 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o /dev/null objcopy: Warning: '/dev/null' is not an ordinary file $ echo $? 1 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o tmp.o $ echo $? 0 There is another flag that creates an separate file based on the object file path: $ cat /dev/null | gcc -ftest-coverage -c -x c - -o /dev/null <stdin>:1: error: cannot open /dev/null.gcno So, we cannot use /dev/null to sink the output. Align the cc-option implementation with scripts/Kbuild.include. With -c option used in cc-option, as-option is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug1
1 files changed, 0 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 96999d4d2dda..9ad9210d70a1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -229,7 +229,6 @@ config DEBUG_INFO_COMPRESSED
bool "Compressed debugging information"
depends on DEBUG_INFO
depends on $(cc-option,-gz=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