On Fri, Apr 3, 2020 at 10:07 AM Leonardo Bras <leona...@linux.ibm.com> wrote: > > Hello Oliver, thank you for the feedback. > Comments inline: > > On Fri, 2020-04-03 at 09:46 +1100, Oliver O'Halloran wrote: > > > > I don't really understand why the flag is needed at all. According to > > PAPR any memory provided by dynamic reconfiguration can be hot-removed > > so why aren't we treating all DR memory as hot removable? The only > > memory guaranteed to be there 100% of the time is what's in the > > /memory@0 node since that's supposed to cover the real mode area. > > All LMBs are listed in DR memory, even the base memory. > > The v1 of the patch would work this way, as qemu would configure it's > DR memory with (DRC_INVALID | RESERVED) flags and the hot-added memory > with (ASSIGNED) flag. Looking for assigned flag would be enough. > > But as of today, PowerVM doesn't seem to work that way. > When you boot a PowerVM virtual machine with Linux, all memory is added > with the same flags (ASSIGNED). > > To create a solution that doesn't break PowerVM, this new flag was made > necessary.
I'm still not convinced it's necessary. Why not check memory@0 and use the size as a clip level? Any memory above that level gets marked as hotpluggable and anything below doesn't. Seems to me that would work on all current platforms, so what am I missing here? > > Best regards, > Leonardo Bras