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Old 03-03-2010, 02:29 PM
Stroller
 
Default Advice for 64-bit n00b?

Hi there,

A new (to me) server has 64-bit CPUs. By my standards this is a REALLY
NICE high specification machine (I appears to be 2 x dual-core), but
in fact it's about 3 years old & is one of the earliest Intel Xeons
that supports 64-bits / AMD64 / EMT64. I think it is 64-bit Pentium 4,
rather than Core 2 architecture.


# cat /proc/cpuinfo | head -n 25
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Xeon(TM) CPU 3.00GHz
stepping : 3
cpu MHz : 2992.346
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 5
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 lm constant_tsc pebs bts pni dtes64 monitor ds_cpl cid cx16
xtpr

bogomips : 5984.69
clflush size : 64
cache_alignment : 128
address sizes : 36 bits physical, 48 bits virtual
power management:


I'm a bit confused by the 36-bit address size mentioned there, but I
assume this is OK. The Gentoo wiki seems to confirm this CPU is 64-
bit: http://tinyurl.com/klv7gc [1]


Is there anything I need to know about working with 64-bits / AMD64 /
EMT64, seeing as I've never done so before?


I have started following the Gentoo Linux AMD64 Handbook, because the
Quick Install Guide is described as "x86". Having untarred the stage I
am surprised to find a lib32 directory. I thought compatibility with
32-bit binaries was optional. Or am I misunderstanding? This is going
to be a headless server & I can't think that it'll need any binary
packages - possibly the management utility for the RAID controller
will be distributed as a binary, I'm not sure yet (the hardware RAID
key was missing when I got this machine ☹)


I'm editing my make.conf and looked at the Gentoo wiki for "Safe
Cflags" - it says 'CHOST="x86_64-pc-linux-gnu"'. But of course
(according to make.conf.example) one shouldn't change CHOST on an
installed system. Will the files in the stage 3 have been compiled
using this CHOST?


Any pointers would be gratefully appreciated - I'm wondering if
there's anything you guys all take for granted that I could mess up if
I don't allow for it early enough in the installation process.


Thanks in advance for any comments,

Stroller.




[1] http://en.gentoo-wiki.com/wiki/Safe_Cflags/Intel#Xeon_w.2FEM64T_.28also_Pentium_4_P6xx_or_Cel eron_M_5xx.29
 
Old 03-03-2010, 02:32 PM
Alan McKinnon
 
Default Advice for 64-bit n00b?

On Wednesday 03 March 2010 17:29:06 Stroller wrote:
> Hi there,
>
> A new (to me) server has 64-bit CPUs. By my standards this is a REALLY
> NICE high specification machine (I appears to be 2 x dual-core), but
> in fact it's about 3 years old & is one of the earliest Intel Xeons
> that supports 64-bits / AMD64 / EMT64. I think it is 64-bit Pentium 4,
> rather than Core 2 architecture.
>
> # cat /proc/cpuinfo | head -n 25
> processor : 0
> vendor_id : GenuineIntel
> cpu family : 15
> model : 4
> model name : Intel(R) Xeon(TM) CPU 3.00GHz
> stepping : 3
> cpu MHz : 2992.346
> cache size : 2048 KB
> physical id : 0
> siblings : 2
> core id : 0
> cpu cores : 1
> apicid : 0
> initial apicid : 0
> fpu : yes
> fpu_exception : yes
> cpuid level : 5
> 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 lm constant_tsc pebs bts pni dtes64 monitor ds_cpl cid cx16
> xtpr
> bogomips : 5984.69
> clflush size : 64
> cache_alignment : 128
> address sizes : 36 bits physical, 48 bits virtual
> power management:
>
>
> I'm a bit confused by the 36-bit address size mentioned there, but I
> assume this is OK. The Gentoo wiki seems to confirm this CPU is 64-
> bit: http://tinyurl.com/klv7gc [1]

that is correct


>
> Is there anything I need to know about working with 64-bits / AMD64 /
> EMT64, seeing as I've never done so before?

Nope, it's just another arch. The days of doing weird funky stuff to get amd64
to work are long gone


>
> I have started following the Gentoo Linux AMD64 Handbook, because the
> Quick Install Guide is described as "x86". Having untarred the stage I
> am surprised to find a lib32 directory. I thought compatibility with
> 32-bit binaries was optional. Or am I misunderstanding? This is going
> to be a headless server & I can't think that it'll need any binary
> packages - possibly the management utility for the RAID controller
> will be distributed as a binary, I'm not sure yet (the hardware RAID
> key was missing when I got this machine ☹)
>
> I'm editing my make.conf and looked at the Gentoo wiki for "Safe
> Cflags" - it says 'CHOST="x86_64-pc-linux-gnu"'. But of course
> (according to make.conf.example) one shouldn't change CHOST on an
> installed system. Will the files in the stage 3 have been compiled
> using this CHOST?

Yes. If you used a recent amd64 stage, it will all be fine.
>
> Any pointers would be gratefully appreciated - I'm wondering if
> there's anything you guys all take for granted that I could mess up if
> I don't allow for it early enough in the installation process.

In make,conf, as long s you are using a reasonably recent gcc:

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


-march=native avoids all that tedious mucking about with trying to figure out
what cpu type you should build for, and moves the heavy lifting off onto the
compiler.



--
alan dot mckinnon at gmail dot com
 

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