On Mon, 2006-03-27 at 15:24 -0500, Yu,Glen [Ontario] wrote: > Hi, > > Our Debian 3.1 (2.4.27-2-686-smp kernel) server contains (among other > things) 4x2GB sticks of RAM giving us a grand total of 8GB, however, > free and cat /proc/meminfo sees roughly only 4GB: > [...snippage...] > I believe this problem can be solved by recompiling the kernel with > CONFIG_HIGHMEM64G=y (at the moment, it's commented out and > CONFIG_HIGHMEM4G=y instead) as long as I have PAE (Physical Address > Extension) enabled (which it is). But before a final decision is to > be made by my supervisor as to exactly what is to be done, we want to > know if recompiling the kernel is our only option, or if there are > others? Basically re-compiling the kernel with the PAE stuff enabled is the only way to get it to be recognized. Unless you goto 64-bit, then there is another limit, that some day we might cross. But, debian has a kernel build system that works very well. Using the Debian Kernel Source, and the kernel-package and a few other things... do some reading before hand and you can make a dpkg -i installable debian kernel-image There are plenty of things to watch out for. So it behooves you to read up on the process a bit. > Also, I've read somewhere (sorry, I forgot where), that there some > overhead is involved when using the PAE, so I was wondering if anybody > has had any experience/comments regarding this or a similar issue, I > would like to hear from you. The overhead for PAE, is more in the form of a penalty or not usable RAM in the 3.5-4.0 (a range but is not 512MB, I don;t properly remember that actual) is not usable by the machine. it seems like it was 3.7GB found out of 4GB with PAE active, or if more, 7.7GB out of 8GB etc... If you can't have that loss, then you should consider only using 4GB. -- greg, greg@gregfolkert.net The technology that is Stronger, Better, Faster: Linux Use Debian GNU/Linux, its a bazaar thing NOTICE: Due to Presidential Executive Orders, the National Security Agency may have read this email without warning, warrant, or notice, and certainly without probable cause. They may do this without any judicial or legislative oversight. You have no recourse nor protection.
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