[kernel-xen] balloon messages from latest kernel-xen

[Glenn Enright]

HI there,

I'm seeing messages like the following in dmesg using the latest 3.8 kernel

System RAM resource [mem 0x28000000-0x2fffffff] cannot be added
xen_balloon: reserve_additional_memory: add_memory() failed: -17

This is on an older Core2 intel MB with only 4G RAM. Everything appears 
to be working normally otherwise. I also see some notes about a similar 
case at http://lists.xen.org/archives/html/xen-devel/2012-12/msg01606.html

I have autoballoon=0 in xl.conf per 
http://wiki.xen.org/wiki/Xen_4.2_Release_Notes and the grub line 
includes dom0_mem, eg

        kernel /xen.gz dom0_mem=max:600M dom0_max_vcpus=1 dom0_vcpus_pin

A custom-built 3.6.10 kernel does not report those messages. Using 
Stevens xen 4.2.1-4 packages in both cases.

I've not tested this on other hardware yet, it may be a peculiarity of 
this platform, or something in the bios setup.

Anyone know why I may be seeing those with the new kernel, or have seen 
and resolved those? It looks like ballooning is built into the kernel, 
can/should that be disabled via grub also?

Regards, Glenn

# grep -i balloon /boot/config-3.8.3-1.el6xen.x86_64
CONFIG_BALLOON_COMPACTION=y
CONFIG_VMWARE_BALLOON=m
CONFIG_VIRTIO_BALLOON=m
CONFIG_XEN_BALLOON=y
CONFIG_XEN_SELFBALLOONING=y
CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y