[email protected] wrote:
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):
Essentially I don't think there is much you can do about this on this
board. The memory space starting at around 3.2GB is being used by the
memory-mapped IO regions for the PCI and PCI Express devices and
motherboard resources and therefore "covers up" the RAM in that part of
the address space. The solution to this is for the system to remap the
affected memory above the 4GB mark, which is possible with Athlon
64/Opteron CPUs and on some of the Intel server chipsets. However, I
don't think any Intel desktop chipsets support this for some
unfathomable reason.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
