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David Hildenbrand says: ==================== virtio-mem: s390 support Let's finally add s390 support for virtio-mem; my last RFC was sent 4 years ago, and a lot changed in the meantime. The latest QEMU series is available at [1], which contains some more details and a usage example on s390 (last patch). There is not too much in here: The biggest part is querying a new diag(500) STORAGE_LIMIT hypercall to obtain the proper "max_physmem_end". The last three patches are not strictly required but certainly nice-to-have. Note that -- in contrast to standby memory -- virtio-mem memory must be configured to be automatically onlined as soon as hotplugged. The easiest approach is using the "memhp_default_state=" kernel parameter or by using proper udev rules. More details can be found at [2]. I have reviving+upstreaming a systemd service to handle configuring that on my todo list, but for some reason I keep getting distracted ... I tested various things, including: * Various memory hotplug/hotunplug combinations * Device hotplug/hotunplug * /proc/iomem output * reboot * kexec * kdump: make sure we properly enter the "kdump mode" in the virtio-mem driver kdump support for virtio-mem memory on s390 will be sent out separately. v2 -> v3 * "s390/kdump: make is_kdump_kernel() consistently return "true" in kdump environments only" -> Sent out separately [3] * "s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM memory devices" -> No query function for diag500 for now. -> Update comment above setup_ident_map_size(). -> Optimize/rewrite diag500_storage_limit() [Heiko] -> Change handling in detect_physmem_online_ranges [Alexander] -> Improve documentation. * "s390/sparsemem: provide memory_add_physaddr_to_nid() with CONFIG_NUMA" -> Added after testing on systems with CONFIG_NUMA=y v1 -> v2: * Document the new diag500 subfunction * Use "s390" instead of "s390x" consistently [1] https://lkml.kernel.org/r/20241008105455.2302628-1-david@redhat.com [2] https://virtio-mem.gitlab.io/user-guide/user-guide-linux.html [3] https://lkml.kernel.org/r/20241023090651.1115507-1-david@redhat.com ==================== Link: https://lore.kernel.org/r/20241025141453.1210600-1-david@redhat.com/ Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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