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author | David Daney <david.daney@cavium.com> | 2012-01-10 15:07:25 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-10 16:30:42 -0800 |
commit | 1399ff86f2a2bbacbbe68fa00c5f8c752b344723 (patch) | |
tree | 7cfb8e346ff8d750cbf33bb0655603e21e394c37 /include/linux/compiler-gcc4.h | |
parent | 1e16a539ac16e7b3a8c2cee188897d4bdb88e6e8 (diff) | |
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kernel.h: add BUILD_BUG() macro
We can place this in definitions that we expect the compiler to remove by
dead code elimination. If this assertion fails, we get a nice error
message at build time.
The GCC function attribute error("message") was added in version 4.3, so
we define a new macro __linktime_error(message) to expand to this for
GCC-4.3 and later. This will give us an error diagnostic from the
compiler on the line that fails. For other compilers
__linktime_error(message) expands to nothing, and we have to be content
with a link time error, but at least we will still get a build error.
BUILD_BUG() expands to the undefined function __build_bug_failed() and
will fail at link time if the compiler ever emits code for it. On GCC-4.3
and later, attribute((error())) is used so that the failure will be noted
at compile time instead.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: DM <dm.n9107@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/compiler-gcc4.h')
-rw-r--r-- | include/linux/compiler-gcc4.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index dfadc96..2f40791 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -29,6 +29,7 @@ the kernel context */ #define __cold __attribute__((__cold__)) +#define __linktime_error(message) __attribute__((__error__(message))) #if __GNUC_MINOR__ >= 5 /* |