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?).
--
Bryan J. Smith b.j.smith@xxxxxxxx
---------------------------------------------------------------------
It is mathematically impossible for someone who makes more than you
to be anything but richer than you. Any tax rate that penalizes them
will also penalize you similarly (to those below you, and then below
them). Linear algebra, let alone differential calculus or even ele-
mentary concepts of limits, is mutually exclusive with US journalism.
So forget even attempting to explain how tax cuts work. ;->
