"the OpenBSD kernel will only recognize 3.1 gig of RAM"?

[hanzer]

While browsing through some of the great tutorials at calomel, I noticed this blurb:

For OpenBSD on our testing system we had eight(8) gig available, but the OpenBSD kernel will only recognize 3.1 gig of that no matter if you use the i386 or AMD64 kernel. In fact, having too much RAM in your box will COST you memory on OpenBSD, as more kernel memory is used up tracking all your RAM. So cutting your ram to 2 GB will probably improve the upper limit. Strange but true.

Is this true?

[jggimi]

No. Not since bigmem became the default for OpenBSD/amd64 on April 4, 2011, for inclusion in OpenBSD 5.0.

Prior to that, bigmem had about 3 years of testing by developers and interested users who were building custom kernels to enable it.

Ref: http://cvsweb.openbsd.org/cgi-bin/cv...-cvsweb-markup

[ocicat]

Originally Posted by hanzer

Is this true?

Reading through the misc@ archives, that site is notorious for posting incorrect information:

http://marc.info/?l=openbsd-misc&w=2&r=1&s=calomel&q=b

[hanzer]

Originally Posted by jggimi

Not since bigmem became the default for OpenBSD/amd64 on April 4, 2011, for inclusion in OpenBSD 5.0.

Thanks. For an i386 machine, I guess it doesn't make sense to install more than 4GB of RAM?

[jggimi]

For i386, the addressable physical memory limit is 3 GB. The 4th GB, if installed, is not addressable. It is my understanding that PAE is used on OpenBSD with virtual address spaces (per process), not physical addressing.

http://en.wikipedia.org/wiki/3_GB_barrier

[hanzer]

Originally Posted by ocicat

Reading through the misc@ archives, that site is notorious for posting incorrect information:

In my experience, errors, ambiguities, omissions, distortions, obfuscations, etc. are fairly common everywhere. I find the articles posted on "that site" to be useful overviews and generally pleasant to read, FWIW.

[Oko]

Originally Posted by hanzer

While browsing through some of the great tutorials at calomel, I noticed this blurb:



Is this true?

Bullshit

predrag@oko$ uname -a
OpenBSD oko.bagdala2.net 5.6 GENERIC.MP#2 amd64
predrag@oko$ sysctl hw | grep mem
hw.physmem=8568832000
hw.usermem=8568791040

Check out misc for my posts with dmesg. About year ago I send dmesg from the server with 64 cores and 512 GB of physical RAM (running OpenBSD amd64). Server ended up running Red Hat because we are using it as a computing node. I will try to dig one of my sparc64 machines with lots of RAM and post dmesg.

[ibara]

Originally Posted by hanzer

Thanks. For an i386 machine, I guess it doesn't make sense to install more than 4GB of RAM?

PAE is being working on now:
http://marc.info/?l=openbsd-tech&m=142122093110713&w=2

[jggimi]

Originally Posted by ibara

PAE is being working on now...

I missed that note at the bottom of mlarkin@'s Email. Thanks!