Hello,
On a dual core Pentium 4 EM64T machine (Intel Desktop Board D915GAV),
we used four 1GB RAM (DDR 400) modules. The BIOS (EV91510A.86A.0444)
detected all the four 1 GB modules, but once the OS is booted, only
~3.1GB is available for usage (from dmesg: "Memory: 3210516k/3267772k
available"; see below). The kernel used is version 2.6.9-22.ELsmp
coming with 'CentOS release 4.2 Final'.
[The four RAM modules have been tested OK with the 'memtest'].
Using "mem=4096m" while booting the kernel also did not help. Searched
through the old messages and it looks like in most of the cases
enabling some memory-hole related option in BIOS is suggested, but in
this case probably the BIOS is fine. Not sure if some kernel
configuration option is missing or if someother version of the kernel
needs to be used.
This being a 64 bit machine, we expected memory-remap to be happening.
Is there a way in which ~900 MB of RAM can be made usable?
Any pointers will be of great help.
Please let me know if more information is needed than the following
transcripts (/proc/iomem and dmesg):