On Wed, 2005-07-20 at 13:42 +0100, Wayne wrote:

Going back to 3gig kernel space 1gig userspace, that's how stock kernels are isnt it?

Stock kernels support a host of models. But the defaults were typically low and conservative, but I haven't compiled a stock kernel in a long time.

All distros I know of have their own standards.

4g/4g was a redhat feature I think..

No, the stock kernel has the 4Gi/4Gi model. But yes, Red Hat installs it by default. I'm sure the number of people who upgraded memory and saw no increase only to call Red Hat tech support were the reason why this is done.

This is, of course, not an issue on x86-64 kernels, which can run the kernel anywhere in the 40-bit physical address space of current x86-64 implementations (both AMD64 and EMT64). If there are issues directly accessing above 4GiB, especially for memory mapped I/O *COUGH*EM64T*COUGH*, they are transparently accommodated.

[ * As several people have noted, what's the advantage of EM64T as a server if it doesn't solve the "bounce buffers" problem? ;-]

I wanted to install fedora before under virtual pc on a mac and was told that 4g/4g was why it failed to boot,

Then rebuild with 1Gi/3Gi instead. It's in there. It's not a Red Hat change from the stock kernel, just a Red Hat default. If you're on the Fedora lists, the first thing they recommend for a performance boost if you have less than 1GiB is to rebuild for the 1Gi/3Gi model.

heard it was out of FC4 so wondered if it was in or out of centos4 (I know the two arent really related just thought somebody would have a quick answer on here but since I think 4g/4g came from redhat

Well, if you really want to point at Red Hat, I guess a _lot_ of things in the kernel _do_ actually come from Red Hat. ;-> But no, it's a _stock_ kernel feature. Again, Red Hat just makes it the default.

• centos 4 is based on redhats srpms then I suppose I

shouldn't have asked since im now answering my own question..)

I would very much assume RHEL 3 and 4 (probably RHEL 2.1) _all_ come with the 4Gi/4Gi model as standard, with an option for the full PAE36/64GiB model.

I'm fairly certain this is how SLES ships as well, if it doesn't already do PAE36/64GiB out-of-the-box by default. At least that how it was back in the SLES 7 day (maybe before the 4Gi/4Gi model option?).