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

[Dale Bewley]

----- "Dustin Henning" <Dustin.Henning at prd-inc.com> wrote:
> 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

I have 4 procs with 16G RAM and no mem paramters in grub at all, and it looks like this:

Linux h 2.6.20-2931.fc7xen #1 SMP Mon Aug 13 10:11:56 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux

# grep 'model name' /proc/cpuinfo
model name      : AMD Opteron(tm) Processor 852
model name      : AMD Opteron(tm) Processor 852
model name      : AMD Opteron(tm) Processor 852
model name      : AMD Opteron(tm) Processor 852

# grep Total /proc/meminfo
MemTotal:     13335552 kB
SwapTotal:     5261240 kB
VmallocTotal: 34359738367 kB

# xm info |grep total
total_memory           : 16319

I have 3 domU's running with each allocated 1G, so 16-3=13 which I suppose explains the MemTotal line above from the perspective of dom0.


On an identical server running RHEL with no xen and I see something a bit different:

Red Hat Enterprise Linux AS release 4 (Nahant Update 5)
Linux z 2.6.9-55.0.2.ELsmp #1 SMP Tue Jun 12 17:58:20 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux

# grep Total /proc/meminfo
MemTotal:     16359284 kB
HighTotal:           0 kB
LowTotal:     16359284 kB
SwapTotal:     5261240 kB
VmallocTotal: 536870911 kB
HugePages_Total:     0

Not sure if that was helpful.
--
Dale Bewley - Unix Administrator - Shields Library - UC Davis
GPG: 0xB098A0F3 0D5A 9AEB 43F4 F84C 7EFD  1753 064D 2583 B098 A0F3