Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a quad socket octo-core system running FreeBSD. Currently, I need to turn off HyperThreading to get it to boot, as FreeBSD only supports 32 CPUs. There were some patches made awhile ago against a trunk version of 8.1, but even after modifying them slightly to work and compile with 8.1-RELEASE, the machine wouldn't boot.

Has there been any progress here? I can't find much good information about it, Google thinks I'm talking about 64-bit architecture and not literally 64 CPUs.

share|improve this question

migrated from stackoverflow.com Jan 14 '11 at 17:51

This question came from our site for professional and enthusiast programmers.

    
No one will need more than 640K of RAM. :) Wow! 64 cores. Nice! –  geoffc Jan 14 '11 at 18:02
    
Wow, as you say it really is difficult to get any information on FreeBSD using more than 64 cpus... closest I got was forums.freebsd.org/showthread.php?t=6731 from 2009! –  Mokubai Jan 14 '11 at 18:10
    
Have a look at this: ftp.freebsd.org/pub/FreeBSD/CERT/advisories/… –  Hunter Jan 14 '11 at 18:39

1 Answer 1

At the end of http://forums.freebsd.org/showthread.php?t=13261, a FreeBSD developer mentions that

AFAIR it was told somewhere that for 64bit archs it should be possible to rise [the number of logical cores] up to 64 without much troubles, except increased memory consumption. It just wasn't tested due to lack of such systems. Further increase will probably require some architectural changes.

That comment was made in April 2010. Earlier posts in the thread quote an include file which specifies the number of cores.

It might help to remember that Google will let you filter out things using syntax like -"64-bit" — though in this case, and perhaps others, the quoted result would have been filtered out. I got there by googling freebsd max cores.

share|improve this answer
    
I've seen that post. However what it describes is not possible - the CPU mask is only 32 bits, that's why the maximum is currently 32. The patch I looked over did something else entirely, and wasn't exactly trivial. I've tried recompiling the kernel with simply MAXCPUS set to 64, the kernel doesn't boot unfortunately. –  Brett Jan 16 '11 at 4:09

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.