On Wed, Jul 15, 2020 at 01:21:06PM +0200, David Hildenbrand wrote: > > At least in v4.1 the kernel will calculate the max address by using > > increment size * increment number and then test if *each* increment is > > available with tprot. > > Yes, we do the same in kvm-unit-tests. But it's not sufficient for > memory devices. > > Just because a tprot succeed (for memory belonging to a memory device) > does not mean the kernel should silently start to use that memory. > > Note: memory devices are not just DIMMs that can be mapped to storage > increments. The memory might have completely different semantics, that's > why they are glued to a managing virtio device. > > For example: a tprot might succeed on a memory region provided by > virtio-mem, this does, however, not mean that the memory can (and > should) be used by the guest.
So, are you saying that even at IPL time there might already be memory devices attached to the system? And the kernel should _not_ treat them as normal memory?
