On 04/10/2018 19:50, Michal Suchánek wrote:

On Thu, 4 Oct 2018 17:45:13 +0200
David Hildenbrand [off-list ref] wrote:

quoted

On 04/10/2018 17:28, Michal Suchánek wrote:

quoted

quoted

The state of the art is to determine what to do with hotplugged
memory in userspace based on platform and virtualization type.  

Exactly.

quoted

Changing the default to depend on the driver that added the memory
rather than platform type should solve the issue of VMs growing
different types of memory device emulation.  

Yes, my original proposal (this patch) was to handle it in the kernel
for known types. But as we learned, there might be some use cases that
might still require to make a decision in user space.

So providing the user space either with some type hint (auto-online
vs. standby) or the driver that added it (system vs. hyper-v ...)
would solve the issue.

Is that not available in the udev event?

Not that I am aware. Memory blocks "devices" have no drivers.

ls -la /sys/devices/system/memory/memory0/subsystem/drivers
total 0

(add_memory()/add_memory_resource() creates the memory block devices
when called from a driver)

Thanks

Michal

-- 

Thanks,

David / dhildenb