Martin,
My computer, a Dell Optiplex 620 has a Intel P4 XEON HT with 4x 1GB RAM. The kernel sees 3.5 GB only.
By default the kernel has HIGHMEM enabled and is set to 64GB.
Check your motherboard documentation.
I will. what would it say? Why is that a motherboard issue? I have no RAID nor PCI controllers which could occupie the last 0.5GB.
I have 4GB GA-K8NN Ultra-SLI 4200+ SMP dual x86_64
21:04 wahoo:~ > free total used free shared buffers cached Mem: 3349376 2275016 1074360 0 131076 1189104 -/+ buffers/cache: 954836 2394540 Swap: 514040 0 514040
so you have the same problem, don't you? actually I thought a 64bit system should not have this problem since it can address natively more memory than a 32bit system which can address only 3GB of memory.
You can reclaim the missing memory if your BIOS supports "Memory hole Remapping". I have an Epox board (9NPA Ultra) and under the DRAM configuration screen there is an option to enable Memory hole Remapping. Some BIOS's support Hardware remapping, some software remapping, and some both. Some don't support it at all. As others pointed out, the missing memory is reserved for PCI devices and the like. When this option is enabled, it remaps the memory reserved for those devices so that the OS sees all 4 GB. Not sure how stable the system is with remapping enabled. With it enabled I had a hang while doing an update, so I turned it off as the .5 GB that I was missing wasn't crucial. I haven't really tested it with the memory hole remapping enabled. Mike -- Michael A. Coan Woodlawn Foundation 524 North Avenue, Suite 203 New Rochelle, NY 10801-3410 Tel: 914-632-3778 Fax: 914-632-5502