Comment 4 for bug 686692

Some updates here: the good news is that I am able to reproduce this on a local CentOS based installation. Bad news so far is that the DomU crashes so quickly that I get no output at all, even when directly attaching to the console on "xm create".

But at least I found a lead. The crashes happen if the guest memory is less than 1G and not dividable by 4. So 615M crashes, but 616 will boot (or 612 and so on). There is also a visible change in the memory layout presented to Linux. While previously the max_pfn was directly used to create an e820 map, there is now some additional 8M added in the data returned by the memory hypercall. I cannot say right now whether that directly relates to the crash or not but one can see that starting a guest with mem=616, Linux will report 624M of memory. There is a lot of shifting around and recalculating going on which I have yet to understand.