On Thu, 2013-02-14 at 15:08 +0100, Bernhard Schmidt wrote: > Hello Ben, > > > This is not memory, it's MMIO (memory-mapped input/output) for the > > emulated VGA card. The kernel controls the addresses used for MMIO for > > PCI devices, but does not control the addresses used for RAM. > > Apparently the system firmware (or in this case the hypervisor) can > > provide hints through ACPI about what addresses it should use, to avoid > > conflicting with hot-added RAM. But the kernel version in squeeze > > ignores those hints. > > > > Does the kernel parameter 'pci=use_crs' avoid this? > > That works fine, thanks! Can this somehow be patched in the kernel or > shall we just change our boot parameters? The change made upstream (in Linux 2.6.34) is to enable use_crs by default when the BIOS is dated 2008 or later (with some specific exceptions). Presumably that includes your VM, so that Linux 3.2 in 'wheezy' doesn't have this problem. I'm wary of backporting that change in 'squeeze', but I think it might be possible to enable use_crs specifically when running under VMware. There should be no harm in using the kernel parameter as a temporary workaround on any VM where you might want to use memory hotplug. Ben. -- Ben Hutchings Absolutum obsoletum. (If it works, it's out of date.) - Stafford Beer
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