path: root/arch
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authorGravatar Peter Korsgaard <peter@korsgaard.com>2014-11-07 19:51:06 +0100
committerGravatar Peter Korsgaard <peter@korsgaard.com>2014-11-07 19:51:06 +0100
commit80e406090893ab5a7b5d78e4d243d12fca2b22fb (patch)
treebe4d799241960cc18bcded0460e5197a5145450d /arch
parente97171db813b49bad3cb2e115b5d598a0a33909c (diff)
arch/Config.in.x86: drop BR2_x86_generic
The fuzzy generic x86 variant doesn't make much sense in the context of Buildroot, and the recent change to use -march instead of -mtune broke it. From the GCC manual: https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/i386-and-x86-64-Options.html#i386-and-x86-64-Options: -mtune=cpu-type Tune to cpu-type everything applicable about the generated code, except for the ABI and the set of available instructions. While picking a specific cpu-type schedules things appropriately for that particular chip, the compiler does not generate any code that cannot run on the default machine type unless you use a -march=cpu-type option. For example, if GCC is configured for i686-pc-linux-gnu then -mtune=pentium4 generates code that is tuned for Pentium 4 but still runs on i686 machines. The choices for cpu-type are the same as for -march. In addition, -mtune supports 2 extra choices for cpu-type: ‘generic’ Produce code optimized for the most common IA32/AMD64/EM64T processors. If you know the CPU on which your code will run, then you should use the corresponding -mtune or -march option instead of -mtune=generic. But, if you do not know exactly what CPU users of your application will have, then you should use this option. As new processors are deployed in the marketplace, the behavior of this option will change. Therefore, if you upgrade to a newer version of GCC, code generation controlled by this option will change to reflect the processors that are most common at the time that version of GCC is released. There is no -march=generic option because -march indicates the instruction set the compiler can use, and there is no generic instruction set applicable to all processors. In contrast, -mtune indicates the processor (or, in this case, collection of processors) for which the code is optimized. Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Diffstat (limited to 'arch')
1 files changed, 0 insertions, 5 deletions
diff --git a/arch/Config.in.x86 b/arch/Config.in.x86
index 0b7919b7ae..8a844dbe94 100644
--- a/arch/Config.in.x86
+++ b/arch/Config.in.x86
@@ -18,12 +18,9 @@ choice
prompt "Target Architecture Variant"
depends on BR2_i386 || BR2_x86_64
default BR2_x86_i586 if BR2_i386
- default BR2_x86_generic if BR2_x86_64
Specific CPU variant to use
-config BR2_x86_generic
- bool "generic"
config BR2_x86_i386
bool "i386"
depends on !BR2_x86_64
@@ -197,7 +194,6 @@ config BR2_ARCH
default "i686" if BR2_x86_athlon
default "i686" if BR2_x86_athlon_4
default "x86_64" if BR2_x86_64
- default "i386" if BR2_x86_generic
config BR2_ENDIAN
default "LITTLE"
@@ -234,4 +230,3 @@ config BR2_GCC_TARGET_ARCH
default "c3" if BR2_x86_c3
default "c3-2" if BR2_x86_c32
default "geode" if BR2_x86_geode
- default "generic" if BR2_x86_generic