Safe Cflags/Intel

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Warning: GCC 4.2 and above support -march=native, which automatically detects the optimum settings to use based on your processor. -march=native also detects and applies additional settings beyond -march specific to your CPU, (eg. -msse4). Unless you have a specific reason not to (e.g. distcc cross-compiling), you should probably be using -march=native rather than anything listed below. To find out what -march=native actually picks on the local hardware see Safe Cflags#-march=native.


Pentium

vendor_id : GenuineIntelb
cpu family : 5
model : 2
model name : Pentium 75 - 200
CHOST="i586-pc-linux-gnu"
CFLAGS="-march=pentium -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium w/ MMX

CHOST="i586-pc-linux-gnu"
CFLAGS="-march=pentium-mmx -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium Pro

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentiumpro -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium II

vendor_id : GenuineIntel
cpu family : 6
model : 3, 5
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium2 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 6
model name      : Mobile Pentium II
stepping        : 10
cpu MHz         : 397.082
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr
bogomips        : 794.75
clflush size    : 32

Celeron (Mendocino), aka Celeron1

vendor_id : GenuineIntel
cpu family : 6
model : 6
stepping : 0
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium2 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 6
model name      : Celeron (Mendocino)
stepping        : 0
cpu MHz         : 334.108
cache size      : 128 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr up
bogomips        : 686.94
clflush size    : 32

Pentium III/ Mobile Celeron

vendor_id : GenuineIntel
cpu family : 6
model : 7, 8, 11
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium3 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 8
model name      : Pentium III (Coppermine)
stepping        : 6
cpu MHz         : 863.934
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse
bogomips        : 1728.97
clflush size    : 32

Celeron (Coppermine)

vendor_id  : GenuineIntel
cpu family  : 6
model  : 8
stepping  : 10 (On a Compaq Presario 1800 this number was 1)
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium3 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Celeron (Willamette)

vendor_id  : GenuineIntel
cpu family  : 15
model  : 1
model name  : Intel(R) Celeron(R) CPU XXXXGHz
stepping  : 3
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium4 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium M(Centrino)/Celeron M

vendor_id  : GenuineIntel
cpu family  : 6
model  : 9 or 13
model name  : Intel(R) Pentium(R) M processor XXXXMHz

For gcc 3.3 or older:

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium3 -msse2 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

For gcc 3.4 and later:

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium-m -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

The Celeron M is based on the Pentium M but it has half the L2 cache and does not support the SpeedStep technology.

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 2.00GHz
stepping        : 8
cpu MHz         : 800.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
                  pat clflush dts acpi mmx fxsr sse sse2 ss tm pbe nx up bts est tm2
bogomips        : 1597.70
clflush size    : 64

Mobile Pentium 4-M (Northwood)

vendor_id  : GenuineIntel
cpu family  : 15
model  : 2
model name  : Mobile Intel(R) Pentium(R) 4 - M CPU X.XXGHz
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium4 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium 4

vendor_id  : GenuineIntel
cpu family  : 15
model  : 4
model name  : Intel(R) Pentium(R) 4 CPU 3.00GHz
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium4 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium 4 (Prescott) / Celeron D

vendor_id : GenuineIntel
cpu family : 15
model : 4
model name  : Intel(R) Pentium(R) 4 CPU 2.80GHz

32-bit profile (x86):

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

64-bit profile (amd64):

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"
Note: You can verify the chip is a Prescott by looking for pni in the flags section of /proc/cpuinfo. This indicates support for SSE3.

In 2004, Intel started branding processors with the Prescott core as Intel Celeron D.

Pentium D 8xx / 9xx

vendor_id : GenuineIntel
cpu family : 15
model  : 4, 6
model name  : Intel(R) Pentium(R) D CPU x.xxGHz

32-bit profile (x86):

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

64-bit profile (amd64):

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Xeon w/o EM64T

vendor_id  : GenuineIntel
cpu family  : 15
model  : 2
model name  : Intel(R) Xeon(TM) CPU 2.80GHz
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=pentium4 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Xeon w/EM64T (also Pentium 4 P6xx or Celeron M 5xx)

vendor_id  : GenuineIntel
cpu family  : 15
model  : 4,6
model name  : Intel(R) Xeon(R) CPU XXXXMHz
model name  : Intel(R) Celeron(R) M CPU 5xx @ XXXGHz

32-bit profile (x86):

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

64-bit profile (amd64):

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Intel Core Solo/Duo, Pentium Dual-Core T20xx/T21xx

vendor_id  : GenuineIntel
cpu family  : 6
model  : 14, 22, 4
model name  : Genuine Intel(R) CPU TXXXX @ X.XXGHz
model name  : Intel(R) Celeron(R) CPU 220 @ 1.20GHz
model name  : Intel(R) Celeron(R) CPU 4X0 @ X.XXGHz
model name  : Intel(R) Celeron(R) M CPU 4X0 @ X.XXGHz
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Notes:

  • It has been confirmed by hongjiu.lu@intel.com that prescott is the correct microarchitecture to use with this CPU. http://article.gmane.org/gmane.comp.gcc.devel/83870
  • The newer (eg. 420) Celeron-M processors are Core Solo based, not Pentium-M based. If your processor's family and model are 6 and 14, then you should use the -march=prescott option.
  • Both the Celeron 4x0 and 220 run fine with Processor family (Pentium M) selected in the kernel.

Core 2 Duo/Quad, Xeon 51xx/53xx/54xx/3360, Pentium Dual-Core T23xx+/Exxxx, Celeron Dual-Core

vendor_id  : GenuineIntel
cpu family  : 6
model  : 23
model name  : Intel(R) Dual-core CPU E5700 @ 3.00GHz
model name  : Intel(R) Core(TM)2 duo CPU E7400 @ 2.80GHz
model name  : Intel(R) Pentium(R) Dual CPU T23xx @ XXXGHz
model name  : Intel(R) Xeon(R) CPU X3360

32 bit profile (x86) for < GCC 4.3:

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

32 bit profile (x86) for >= GCC 4.3:

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for < GCC 4.3

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for >= GCC 4.3

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Core i7 and Core i5, Xeon 55xx

vendor_id       : GenuineIntel
cpu family      : 6
model           : 26
model name      : Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz
vendor_id       : GenuineIntel
cpu family      : 6
model           : 37
model name      : Intel(R) Core(TM) i5 CPU         650  @ 3.20GHz / 660 @ 3.33 GHz
vendor_id       : GenuineIntel
cpu family      : 6
model           : 42
model name      : Intel(R) Core(TM) i5-2430M CPU @ 2.40GHz
stepping        : 7
cpu MHz         : 2394.550
cache size      : 3072 KB
vendor_id       : GenuineIntel
cpu family      : 6
model           : 26
model name      : Intel(R) Xeon(R) CPU          X5570  @ 2.93GHz

32 bit profile (x86)

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -fomit-frame-pointer -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for < GCC 4.3

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for GCC 4.3

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -mtune=generic -O2 -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for GCC 4.6

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=corei7 -O2 -pipe"
CXXFLAGS="${CFLAGS}"
Warning: Note that Core i Sandy Bridge CPUs use a march and mtune of corei7-avx not corei7. Sandy Bridge Pentium and Celeron CPUs maintain march and mtune of corei7. See the man page for gcc.

Atom 230, Atom 330, Atom N-Series

vendor_id       : GenuineIntel
cpu family      : 6
model           : 28
model name      : Intel(R) Atom(TM) CPU  230   @ 1.60GHz
stepping        : 2
cpu MHz         : 1596.175
cache size      : 512 KB
vendor_id       : GenuineIntel
cpu family      : 6
model           : 38
model name      : Genuine Intel(R) CPU        @ 1.60GHz
stepping        : 1
cpu MHz         : 1600.033
cache size      : 512 KB

32 bit profile (x86):

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=atom -O2 -fomit-frame-pointer -pipe"
CXXFLAGS="${CFLAGS}"

32 bit gcc 4.5.3 (x86)

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=native -O2 -fomit-frame-pointer -pipe -mfpmath=sse"
CXXFLAGS="${CFLAGS}"

These more aggressive flags above improve single threaded performance benchmarks (ie nbench) on the atom 330 with GCC 4.5.3 considerably, most notably there is a floating point performance increase of ~20%.

64 bit profile (amd64) for < GCC 4.3:

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for GCC 4.3 and 4.4:

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -mtune=generic -pipe"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64) for >= GCC 4.5:

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=atom -O2 -pipe"
CXXFLAGS="${CFLAGS}"