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authorLinus Torvalds <torvalds@linux-foundation.org>2020-07-08 20:48:35 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-07-08 20:48:35 +0300
commit6ec4476ac82512f09c94aff5972654b70f3772b2 (patch)
treea73eea98a918b03ee9893a325d6e30d75c64e800 /include/linux/bits.h
parentdcde237b9b0eb1d19306e6f48c0a4e058907619f (diff)
downloadlinux-6ec4476ac82512f09c94aff5972654b70f3772b2.tar.xz
Raise gcc version requirement to 4.9
I realize that we fairly recently raised it to 4.8, but the fact is, 4.9 is a much better minimum version to target. We have a number of workarounds for actual bugs in pre-4.9 gcc versions (including things like internal compiler errors on ARM), but we also have some syntactic workarounds for lacking features. In particular, raising the minimum to 4.9 means that we can now just assume _Generic() exists, which is likely the much better replacement for a lot of very convoluted built-time magic with conditionals on sizeof and/or __builtin_choose_expr() with same_type() etc. Using _Generic also means that you will need to have a very recent version of 'sparse', but thats easy to build yourself, and much less of a hassle than some old gcc version can be. The latest (in a long string) of reasons for minimum compiler version upgrades was commit 5435f73d5c4a ("efi/x86: Fix build with gcc 4"). Ard points out that RHEL 7 uses gcc-4.8, but the people who stay back on old RHEL versions persumably also don't build their own kernels anyway. And maybe they should cross-built or just have a little side affair with a newer compiler? Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/bits.h')
-rw-r--r--include/linux/bits.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 4671fbf28842..7f475d59a097 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -18,8 +18,7 @@
* position @h. For example
* GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
*/
-#if !defined(__ASSEMBLY__) && \
- (!defined(CONFIG_CC_IS_GCC) || CONFIG_GCC_VERSION >= 49000)
+#if !defined(__ASSEMBLY__)
#include <linux/build_bug.h>
#define GENMASK_INPUT_CHECK(h, l) \
(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \