EM64T support

[jason]

Stewart Morgan wrote:

>
> Hi,
>
>     I'm putting together a (dual-CPU) web/mail server and I have a 
> quandary regarding CPUs: I'd like to use the features on the EM64T 
> Intel Xeons. However, from reading around, there is only support in 
> the AMD64 arm of FreeBSD-5.
>
>
>     Since these are extensions, would I be able to use a pair of Xeons 
> with EM64T and run FreeBSD-4.10 until such time as FreeBSD-5 becomes 
> production ready (5.3?), or should I stick with straight Xeon/XeonMP?
>
>
> Thanks,
>
>
> Stewart.
>
>
> _______________________________________________
> freebsd-questions at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to 
> "freebsd-questions-unsubscribe at freebsd.org"
>
It is my understanding nocona p4/xeons copy amd64 leaving out only 3dnow 
and the nx bit and add 2 obscure instructions to make a emt64 binary 
incompatible with amd64.  If these 2 instructions are not used there are 
no problems between the 2.  Same can be said for 3dnow and the nx bit.  
Do you know intel is in a rush to get out a new version that supports 
the nx bit?  That would be a big boost for security on any platform. 

Also I heard about intel using the 36bit pae tech in place of the 40 bit 
physical addressing amd uses, causing more incompatabliites between the 
2.  In effect when you compile binaries for amd64 you software may not 
work on intels stuff.

http://www.amdzone.com/modules.php?op=modload&name=News&file=article&sid=894
http://www.theinquirer.net/?article=17181
http://www.extremetech.com/article2/0,1558,1274604,00.asp
http://www.geek.com/news/geeknews/2004Jun/bch20040714025978.htm

Really I would recommend going with the original, not a clone from intel 
if you want 64bits and lots of other cool and fast features now(I love 
saying this!).  Or wait until intel gets it right.

I don't work at amd and am not a spokesperson, but I am a fan boy.  Feel 
free to take what I say with a grain, or a whole shaker of salt, just 
don't ignore it please.

The amd stuff also scales much better than xeon mp too.  Have you seen 
one of the many benchmarks that show amd64 chips whipping up on intel stuff?

http://www.anandtech.com/linux/showdoc.aspx?i=2163
http://www.forbes.com/prnewswire/feeds/prnewswire/2004/07/26/prnewswire200407260800PR_NEWS_B_NWT_SF_SFM028.html
http://www.tweakers.net/nieuws/26660  notice how a 4x xeon at 1.6 is 
only ahead of a 2x amd64 at 1.8 by what I would call within margin of error!
http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_8796_8800,00.html
http://mpc.nacs.uci.edu/opteron.html
http://www.aceshardware.com/forum?read=95035921
http://lists.debian.org/debian-amd64/2003/07/msg00025.html
http://www.overclockers.at/showthread.php?threadid=120480
http://www.digit-life.com/articles2/insidespeccpu/insidespeccpu2000-opteron2.html


I hope I was able to help you, but I think I may have left you more 
confused. :-(
I hope I was able to help you to at least give amd a chance. :-)

Jason