Hi, I'm also seeing this.
With: GRUB_CMDLINE_XEN="dom0_mem=1024M,max:1024M …" I see a flurry of "xen:balloon: Cannot add additional memory (-17)" messages every time a domU is shut down. In this configuration I note that I also see with "free -m" that dom0 has 929M, though "xl list" shows 1024M. I can run "xl mem-set 0 1024" without visible error but it does not prevent the error messages being logged. With: GRUB_CMDLINE_XEN="dom0_mem=1024M …" I do not see any of the balloon error messages. In this configuration "free -m" shows 768M RAM for dom0, though "xl list" still shows 1024M. xen-hypervisor-4.4-amd64 4.4.1-9+deb8u3 linux-image-3.16.0-4-amd64 3.16.7-ckt20-1+deb8u2 I'm guessing that the reason I end up with 768M RAM in dom0 is because I have not specified the *maximum* RAM for dom0, so the kernel scales structures for the possible case of dom0 getting the entire 128G of RAM at some point. I added "mem=1G" to the Linux kernel command line and then dom0 boots with "free -m" showing 930M. So, at the moment I am running with "dom0_mem=1024M" on the Xen command line, "mem=1G" on the Linux kernel command line, and "autoballoon=off" in /etc/xen/xl.conf. This seems to avoid the xen:balloon error messages and provide something more like thr expected amount of dom0 memory. Is there a downside of not specifying the ",max:1024M" part? Cheers, Andy
