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Then Linux fails trying to allocate its lowmem trampoline (which really it shouldn't need when running in PV mode), ultimately leading to panic("Real mode trampoline was not allocated"); in their init_real_mode(). While for PV I think it is clear that the easiest is to avoid trampoline setup in the first place, iirc PVH Dom0 also tries to mirror the host memory map to its own address space. Does PVH Linux require a lowmem trampoline? While the two pages here are just enough for Xen's trampoline, I still wonder whether we want to adjust -mapbs behavior. Since whatever we might do leaves a risk of conflicting with true firmware (mis)use of that space, the best I can think of right now would be another option altering behavior (or providing altered behavior). Yet such an option would likely need to be more fine-grained then than covering all of the low Mb in one go. Which feels like both going too far and making it awkward for people to figure out what value(s) to use ... Thoughts anyone? Thanks, Jan