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Date: Tue, 16 Aug 2016 10:37:58 +1000 From: Alistair Popple <alistair@...ple.id.au> To: bsingharora@...il.com Cc: linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org, benh@...nel.crashing.org, stewart@...ux.vnet.ibm.com, mpe@...erman.id.au Subject: Re: [PATCH] powerpc/powernv: Initialise nest mmu Balbir, <snip> > > + /* Update partition table control register on all Nest MMUs */ > > + opal_nmmu_set_ptcr(-1UL, __pa(partition_tb) | (PATB_SIZE_SHIFT - 12)); > > + > > Just wondering if > > 1. Instead of using -1 for all cpus, we should do > for_each_online_cpu() { > opal_numm_set_ptcr(...) > } Good question, but I don't think it makes sense to do that. The NMMU is per-chip/socket rather than per-cpu so it shouldn't be tied to onlining/offlining of individual CPUs. > 2. In cpu hotplug path do the same when onlining and set to NULL on > offlining? Again, the nmmu isn't tied to a specific CPU but rather a chip/socket. So in theory at least it's possible that all CPUs in a chip could be offline but other units on the chip could still be using the nmmu so we wouldn't want to disable the nmmu at that point. > I think we should definitely try and become hotplug aware from the OS > view point and drive it from the OS > > What do you think? > > Balbir Singh.
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