With sys-devel/gcc-4.7.3-r1 using native mode looked like this gcc -march=native -E -v - </dev/null 2>&1 | grep cc1 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.7.3/cc1 -E -quiet -v - -march=corei7 -mcx16 -msahf -mno-movbe -mno-aes -mno-pclmul -mpopcnt -mno-abm -mno-lwp -mno-fma -mno-fma4 -mno-xop -mno-bmi -mno-bmi2 -mno-tbm -mno-avx -mno-avx2 -msse4.2 -msse4.1 -mno-lzcnt -mno-rdrnd -mno-f16c -mno-fsgsbase --param l1-cache-size=32 --param l1-cache-line-size=64 --param l2-cache-size=4096 -mtune=corei7 While with sys-devel/gcc-4.8.1-r1 it seems broken as cache is set to 0 for l1 cache and only 256kb for L2 cache... gcc -march=native -E -v - </dev/null 2>&1 | grep cc1 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.1/cc1 -E -quiet -v - -march=corei7 -mcx16 -msahf -mno-movbe -mno-aes -mno-pclmul -mpopcnt -mno-abm -mno-lwp -mno-fma -mno-fma4 -mno-xop -mno-bmi -mno-bmi2 -mno-tbm -mno-avx -mno-avx2 -msse4.2 -msse4.1 -mno-lzcnt -mno-rtm -mno-hle -mno-rdrnd -mno-f16c -mno-fsgsbase -mno-rdseed -mno-prfchw -mno-adx -mfxsr -mno-xsave -mno-xsaveopt --param l1-cache-size=0 --param l1-cache-line-size=0 --param l2-cache-size=256 -mtune=corei7 Acording to Intel http://ark.intel.com/products/46472/Intel-Core-i3-530-Processor-4M-Cache-2_93-GHz it does have 4096kb not only 256 So does say cat /proc/cpuinfo processor : 0-3 vendor_id : GenuineIntel cpu family : 6 model : 37 model name : Intel(R) Core(TM) i3 CPU 530 @ 2.93GHz stepping : 2 microcode : 0xe cpu MHz : 1197.000 cache size : 4096 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 2 apicid : 1 initial apicid : 1 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm arat dtherm tpr_shadow vnmi flexpriority ept vpid bogomips : 5866.46 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management:
Also Core i7 860 it's affected. L1 cache size it's set to 0: gcc version 4.8.1 (Gentoo 4.8.1-r1 p1.2, pie-0.5.7) COLLECT_GCC_OPTIONS='-v' '-Q' '-march=native' '-O2' '-o' 'test' /usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.1/cc1 -v test.c -march=corei7 -mcx16 -msahf -mno-movbe -mno-aes -mno-pclmul -mpopcnt -mno-abm -mno-lwp -mno-fma -mno-fma4 -mno-xop -mno-bmi -mno-bmi2 -mno-tbm -mno-avx -mno-avx2 -msse4.2 -msse4.1 -mno-lzcnt -mno-rtm -mno-hle -mno-rdrnd -mno-f16c -mno-fsgsbase -mno-rdseed -mno-prfchw -mno-adx -mfxsr -mno-xsave -mno-xsaveopt --param l1-cache-size=0 --param l1-cache-line-size=0 --param l2-cache-size=256 -mtune=corei7 -dumpbase test.c -auxbase test -O2 -version -o /tmp/ccSMZYsA.s processor : 7 vendor_id : GenuineIntel cpu family : 6 model : 30 model name : Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz stepping : 5 microcode : 0x4 cpu MHz : 1200.000 cache size : 8192 KB physical id : 0 siblings : 8 core id : 3 cpu cores : 4 apicid : 7 initial apicid : 7 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm ida dtherm tpr_shadow vnmi flexpriority ept vpid bogomips : 5614.00 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management:
Upstream says this bug is fixed in 4.8.2, see: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57657
http://sources.gentoo.org/viewcvs.py/gentoo/src/patchsets/gcc/4.8.1/gentoo/96_all_pr57657_native-intel-cacheparam.patch?rev=1.1&view=markup
Fixed in 4.8.2.
