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| author | Michal Marek <mmarek@suse.cz> | 2011-05-02 12:51:15 +0200 |
|---|---|---|
| committer | Michal Marek <mmarek@suse.cz> | 2011-05-03 10:50:54 +0200 |
| commit | 8417da6f2128008c431c7d130af6cd3d9079922e (patch) | |
| tree | 79bfdaadfc1548826651b9b0378e70e60cdc7720 /Documentation/kbuild | |
| parent | bffd2020a972a188750e5cf4b9566950dfdf25a2 (diff) | |
| download | lwn-8417da6f2128008c431c7d130af6cd3d9079922e.tar.gz lwn-8417da6f2128008c431c7d130af6cd3d9079922e.zip | |
kbuild: Fix passing -Wno-* options to gcc 4.4+
Starting with 4.4, gcc will happily accept -Wno-<anything> in the
cc-option test and complain later when compiling a file that has some
other warning. This rather unexpected behavior is intentional as per
http://gcc.gnu.org/PR28322, so work around it by testing for support of
the opposite option (without the no-). Introduce a new Makefile function
cc-disable-warning that does this and update two uses of cc-option in
the toplevel Makefile.
Reported-and-tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 835b64acf0b4..47435e56c5da 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -501,6 +501,18 @@ more details, with real examples. gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options + cc-disable-warning + cc-disable-warning checks if gcc supports a given warning and returns + the commandline switch to disable it. This special function is needed, + because gcc 4.4 and later accept any unknown -Wno-* option and only + warn about it if there is another warning in the source file. + + Example: + KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) + + In the above example, -Wno-unused-but-set-variable will be added to + KBUILD_CFLAGS only if gcc really accepts it. + cc-version cc-version returns a numerical version of the $(CC) compiler version. The format is <major><minor> where both are two digits. So for example |