On 15.07.20 12:53, Heiko Carstens wrote: > On Wed, Jul 15, 2020 at 11:19:03AM +0200, David Hildenbrand wrote: >> On 14.07.20 12:17, Claudio Imbrenda wrote: >>> shouldn't it return all the hotplugged areas once hotplugging is >>> enabled? >> >> No, that would be dangerous and wrong. Memory ranges part of memory >> devices never must be indicated as part of hw/firmware interfaces to >> indicate valid boot memory. Memory provided via memory devices >> (virtio-mem, virtio-pmem, ...) has different semantics than ordinary >> hotplugged memory, and unmodified OSs (esp., older Linux versions) >> should not silently try to make use of any such memory. It's not just >> some hotplugged memory a guest OS should detect+use during boot as >> system ram. Thanks! > > How is kdump supposed to work, if there is no mechanism to figure out > which memory ranges have been added dynamically to the system?
Like other archs (esp x86-64), we would want to revive letting user space (kexec-tools) prepare the dump header, specifying the memory ranges. Would be necessary under KVM only, if virtio-mem is detected. (Note: I am not sure if we would currently dump standby memory that has been onlined from a kdump kernel.) -- Thanks, David / dhildenb
