On Tue, Apr 10, 2018 at 01:02:45PM +1000, David Gibson wrote: > On Mon, Apr 09, 2018 at 11:55:38AM +0530, Bharata B Rao wrote: > > The new property ibm,dynamic-memory-v2 allows memory to be represented > > in a more compact manner in device tree. > > I still need to look at this in more detail, but to start with: > what's the rationale for this new format? > > It's more compact, but why do we care? The embedded people always > whinge about the size of the deivce tree, but I didn't think that was > really a concern with PAPR.
Here's a real example of how this has affected us earlier: SLOF's CAS FDT buffer size was initially 32K, was changed to 64k to support 1TB guest memory and again changed to 2MB to support 16TB guest memory. With ibm,dynamic-memory-v2 we are less likely to hit such scenarios. Also, theoretically it should be more efficient in the guest kernel to handle LMB-sets than individual LMBs. We aren't there yet, but I believe grouping of LMBs should eventually help us do memory hotplug at set (or DIMM) granularity than at individual LMB granularity (Again theoretical possibility) Regards, Bharata.
