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paras
n00b
Joined: 28 Mar 2004
Posts: 5
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 Posted: Fri Apr 30, 2004 11:03 am Post subject: centrino laptop - what arch / cflags to chose? |
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in kernelconfig:
pentium m or pentium4?
cflags:
--march=pentium4?
thanks in advance |
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jkt
Retired Dev
Joined: 06 Feb 2004
Posts: 1250
Location: Prague, Czech republic, EU
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| Posted: Fri Apr 30, 2004 11:36 am Post subject: |
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| pentium is for original pentiums, use pentium4. btw, there is only one dash: "-march=pentium4" |
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brodo
Guru
Joined: 15 Apr 2003
Posts: 319
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| Posted: Fri Apr 30, 2004 1:55 pm Post subject: Re: centrino laptop - what arch / cflags to chose? |
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| paras wrote: | in kernelconfig:
pentium m or pentium4? |
pentium m. The processor which is part of the centrino technology is named "Pentium M"
| paras wrote: |
cflags:
--march=pentium4?
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-march=pentium3. The Pentium M is built on top of the pentium 3 architecture; pentium 4 is different. |
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Voltago
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Joined: 02 Sep 2003
Posts: 2593
Location: userland
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| Posted: Fri Apr 30, 2004 2:01 pm Post subject: |
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These are my CFLAGS for my centrino laptop
| Code: | | CFLAGS="-Os -march=pentium3 -pipe -frename-registers -fomit-frame-pointer -s -falign-functions=64" |
and so far I haven't noticed any problems. |
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deprecated
Tux's lil' helper
Joined: 21 Aug 2002
Posts: 118
Location: Madison, WI
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| Posted: Fri Apr 30, 2004 3:03 pm Post subject: |
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Voltage you forgot -msse2 in your CFlags. The Pentium M may be closer to a P3 than a P4, but it does have sse2 support, and you definitely want that included.
If you use the -march=pentium4 option, sse2 support is included by default.
--Dep
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jkt
Retired Dev
Joined: 06 Feb 2004
Posts: 1250
Location: Prague, Czech republic, EU
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| Posted: Fri Apr 30, 2004 6:28 pm Post subject: |
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sorry, Im totaly blind  , I haven't seen the "M" letter ( |
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thundersteele
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Joined: 30 Aug 2003
Posts: 219
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| Posted: Fri Apr 30, 2004 7:11 pm Post subject: |
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I am running happily with the following flags:
"-march=pentium4 -O3 -fomit-frame-pointer -pipe"
nothing else. P4 flag didn't make any problems so far. Of course you should choose Pentium M in your Kernel, the Centrino CPU is simply an Pentium M. |
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jcmorris
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Joined: 11 Jun 2003
Posts: 174
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| Posted: Fri Apr 30, 2004 8:37 pm Post subject: |
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| Quote: | I am running happily with the following flags:
"-march=pentium4 -O3 -fomit-frame-pointer -pipe"
nothing else. P4 flag didn't make any problems so far. Of course you should choose Pentium M in your Kernel, the Centrino CPU is simply an Pentium M. |
Of course you will run happily with that, except the timing will be non-optimal. What people don't realize is that the P4 "netburst" stuff is a totally different beast from anything Intel produced before. A lot of things that were optimal for a Pentium II/III ran poorly on the P4 because of extra internal shifts and extra things that needed to go on within the P4 core during execution. When the Centrino was developed, Intel's Israeli team took the blueprints of the PentiumPro (PII and PIII), and modified it. The Centrino responds better to PIII timing than with the Pentium 4. DON'T USE PENTIUM 4 TIMING ON A PENTIUM-PRO CORE.
jcm
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Desktop:
Athlon64 3000+ (Socket 939 Venice)
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Voltago
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Joined: 02 Sep 2003
Posts: 2593
Location: userland
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| Posted: Fri Apr 30, 2004 9:52 pm Post subject: |
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| deprecated wrote: | Voltage you forgot -msse2 in your CFlags. The Pentium M may be closer to a P3 than a P4, but it does have sse2 support, and you definitely want that included.
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Whoops, sounds like I've some serious recompiling to do... thanks, I didn't know this... |
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mooerito
Apprentice
Joined: 16 Dec 2003
Posts: 187
Location: Zurich/Switzerland
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| Posted: Sat May 01, 2004 12:52 pm Post subject: |
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i had march=pentium4 before and i had some serious problems (specially with power manaagement and other hardware related stuff), after i stepped back to pentium3 it was ok. my current flags are
| Code: | | CFLAGS="-O2 -march=pentium3 -pipe -fomit-frame-pointer -fforce-addr -frename-registers -fprefetch-loop-arrays -falign-functions=64" |
so far everything is running snooth. but i will add the msse2 stuff now, didnt have that before.
afaik with gcc3.4 there will be a march=pentiumM. can somebody with more compilerknowldge than me confirm that? |
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jcmorris
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Joined: 11 Jun 2003
Posts: 174
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| Posted: Sat May 01, 2004 2:16 pm Post subject: |
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According the to the documentation, it should have -march=pentium-m. You know, GCC-3.4 stable is out now, I need to build this 
jcm
_________________
Desktop:
Athlon64 3000+ (Socket 939 Venice)
Asus A8N-SLI
1GB Dual-Channel DDR 3200
NVidia Geforce 6800 256MB
Laptop:
IBM R40
Pentium M 1.4 GHz
256 MB RAM |
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forceflow2
Guru
Joined: 16 Apr 2003
Posts: 464
Location: South Carolina
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| Posted: Sat May 01, 2004 3:01 pm Post subject: |
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Already tried it, doesn't seem to work
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That rank under my username doesn't mean I know everything, it just means I ask a lot of questions. |
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paras
n00b
Joined: 28 Mar 2004
Posts: 5
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| Posted: Sat May 01, 2004 5:56 pm Post subject: |
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hm, so -march=pentium-m doesn't work yet?
OK, I'll go for "-march=pentium3 -O2 -msse2 -fomit-frame-pointer -pipe" then, i need a stable system 
Thank you all. |
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thundersteele
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jcmorris
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Joined: 11 Jun 2003
Posts: 174
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| Posted: Sun May 02, 2004 12:54 am Post subject: |
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Sorry guys, I was reading the test version of the gcc docs 
jcm
_________________
Desktop:
Athlon64 3000+ (Socket 939 Venice)
Asus A8N-SLI
1GB Dual-Channel DDR 3200
NVidia Geforce 6800 256MB
Laptop:
IBM R40
Pentium M 1.4 GHz
256 MB RAM |
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mooerito
Apprentice
Joined: 16 Dec 2003
Posts: 187
Location: Zurich/Switzerland
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| Posted: Thu May 13, 2004 8:33 am Post subject: |
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i added the -msse2 flag to my config and yesterday i was getting floatin point exceptions when using python. when i took away the flags and recompiled the numarray lib everything was runnig smooth again. so there might be still some trouble using those flags, i think ill leave them off for the time being.
Last edited by mooerito on Thu May 13, 2004 9:57 am; edited 1 time in total |
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Voltago
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Joined: 02 Sep 2003
Posts: 2593
Location: userland
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| Posted: Thu May 13, 2004 9:42 am Post subject: |
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Mooerito, did you use -march=pentium3?
And doesn't -march=pentium3 imply -mmmx? In that case, the -msse2 flag alone would be to blame. |
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mooerito
Apprentice
Joined: 16 Dec 2003
Posts: 187
Location: Zurich/Switzerland
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| Posted: Thu May 13, 2004 9:56 am Post subject: |
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ok youre right there (i used pentium3). i forgot about mmmx being already included in march=pentium3
i just corrected my post up there. |
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