CPUTYPE in general - was Re: Which CPUTYPE for a dualcore Xeon on AMD64

[Garrett Cooper]

Mike Meyer wrote:
> In <4680895A.5060700 at u.washington.edu>, Garrett Cooper <youshi10 at u.washington.edu> typed:
>   
>> Martin Turgeon wrote:
>>     
>>> Mike Meyer a écrit :
>>>       
>>>> In <20070625192308.GA14544 at freebsd.org>, Roman Divacky 
>>>> <rdivacky at freebsd.org> typed:
>>>> For the record, I believe the nocona cores are:
>>>> pentium 4/some prescott, prescott 2m, cedar mill
>>>> pentium D/all
>>>> core 2 duo/all
>>>> All xeons with sse3 except the sossaman cored Xeon LV.
>>>>
>>>> The prescott cores are:
>>>> pentium 4/some prescott
>>>> xeon lv (sossaman core)
>>>> core solo
>>>> core duo
>>>>         
>>> Thanks a lot for the precision, I will use nocona for my dual core Xeon.
>>>       
>
>   
>> Cedar Mill: Last P4 processor. Followup to Prescott.
>> Nocona: Xeon server processor code name -- first CPU with EMT64 (amd64) 
>> compatibility [and hence first non-IA64 bit Xeon processor to feature 
>> 64-bit compatibility; not sure if it was the first non-IA64 64-bit 
>> designed Intel processor].
>> Prescott: Single-core processor with HTT. Base CPU for [later 
>> generation] P4 processors, and the dual core Pentium D [basically the 
>> larger cousin of the Northwood CPUs]. Prescott was compacted into Cedar 
>> Mill -- from a 90nm (?) process to 65nm.
>>     
>
> From what I can tell, the Prescott went through a number of
> iterations; the first of them didn't have HTT, or had it but it was
> disabled. Later versions added that, EMT64, virtualization, and other
> things. If my information is correct, the nocona was the first version
> of the prescott core with em64t, and only used in Xeons.
>   
There was a big difference between the Prescott CPU core and the Nocona 
core though, in terms of technology (Pentium 4 vs Core/Core2). 
Apparently the pipelines for the CPU were similar for the desktop CPU 
though, some have claimed. I haven't looked at the RTL though, so I 
can't be sure for myself whether or not that's the case.
> And yes, I believe prescott and following were 90nm until Cedar Mill.
>   
Ok, that's what I thought (since fab screen size goes by 15nm each time 
nowadays).
>>     Intel suggests using -march=prescott (32-bit) and -march=nocona 
>> (64-bit) with gcc on Core2Duo processors and equivalent Xeons.
>>     
>
> Note that /usr/share/mk/sys.mk includes bsd.mk.cpu, which overrides
> CPUTYPE if it's set to prescott or nocona. It turns nocona into
> prescott if you're building for i386 and prescott into nocona if
> you're building for amd64. So the correct answer to the question "Do I
> set CPUTYPE to nocona or prescott in /etc/make.conf?" would seem to be
> "It doesn't matter."
Hmmm... interesting.. Seems like a bit ambitious for bsd.mk.cpu, if the user knows what they're doing.

>>     You can also find your CPU's type by going to this page: 
>> http://www.intel.com/products/server/processors/index.htm?iid=serv_body+proc, 
>> and searching for the appropriate model number. Your frequency and model 
>> should be reported in your BIOS, if not the first couple lines of dmesg 
>> in FreeBSD.
>>     
>
> I've never seen those report core names. Possibly you're referring
> specifically to the Xeon cpu model numbers?
>   
Yeah, that's exactly what I meant.
-Garrett