[Fedora-xen] 64-Bit RAM Detection >4GB?

[Dustin Henning]

The grub installed with Fedora has a bug that causes xen (and sometimes
other kernels) to detect the memory wrong.
Bug URLs follow:
xen-users mailing list archive:
[url]http://lists.xensource.com/archives/html/xen-users/2007-08/msg00028.htm
l[/url]
Bugzilla:
[url]https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=250299[/url]

Theoretically, it could be argued that the BIOS is the problem and not grub,
I mean, it sounds like Dale's machine was functional without this patch, and
MSI isn't exactly a Linux Player.  Either way, the patch suggested in those
two locations resolved my issue.

-----Original Message-----
From: fedora-xen-bounces at redhat.com [mailto:fedora-xen-bounces at redhat.com]
On Behalf Of Dustin Henning
Sent: Thursday, October 18, 2007 16:00
To: fedora-xen at redhat.com
Subject: [Fedora-xen] 64-Bit RAM Detection >4GB?

       I have a Core 2 Quad with 8 GiB of RAM.  When I installed FC7
(2.6.22.9-91.fc7), it only detected 4GiB (BIOS detects 8GiB).  I added
mem=8G to the kernel line in grub.conf, and then Gnome System Monitor showed
7.1GiB (vs I think 4.0).  I then changed that to mem=16G, and the Gnome
System Monitor shows 7.8 GiB.  /proc/meminfo MemTotal shows 8201832kB, so
that seems about right.  That said, the problem seems to be solved for the
kernel mentioned above.
	However, and this is why I am submitting this to the fedora-xen
mailing list, the virtualization kernel (2.6.20-2936.fc7xen) shows 3.1GiB in
Gnome System Monitor and 3214456KB in /proc/meminfo MemTotal.  Additionally,
"xm info" shows 3327 for total memory, so the problem isn't that it is there
but not assigned to dom0.  I tried the same thing with grub.conf for xen,
but it did not work, mem=8G and mem=16G had no effect (this is shown to be a
valid parameter in the Xen manual at
[http://tx.downloads.xensource.com/downloads/docs/user/#SECTION0413000000000
0000000]).  Since it didn't work on the kernel line, I tried it on the
module (vmlinuz) line that has the other FC grub arguments, and that did not
work either; then I tried placing that on both lines (also to no avail).  I
also tried dom0_mem=8G on the kernel line, and that caused a kernel panic
stating not enough physical memory (got the same thing with dom0_mem=4G).
	Finally, as a side note, /proc/meminfo VmallocTotal shows
34359738367kB regardless of all of the above, and I don't know if that is
normal or not (swap partition is 2GiB).  Please let me know if you have
fedora 7 x86_64 xen working with >4GB of memory, if there is any additional
information that might be helpful, or if you have any suggestions I might
try in order to resolve this.  Thank you,
	Dustin