On Mon, Apr 29, 2019 at 04:58:09PM +0000, Luck, Tony wrote: > > ia64 has a such a huge number of memory model choices. Maybe we > > need to cut it down to a small set that actually work. > > SGI systems had extremely discontiguous memory (they used some high > order physical address bits in the tens/hundreds of terabyte range for the > node number ... so there would be a few GBytes of actual memory then > a huge gap before the next node had a few more Gbytes). > > I don't know of anyone still booting upstream on an SN2, so if we start doing > serious hack and slash the chances are high that SN2 will be broken (if it isn't > already). When I wrote this, I thought of !NUMA: flat mem NUMA: sparsemem SN2: discontig based on Meelis report. But now that you mention it, I bet SN2 has already died slow death from bitrot. It is so different in places, and it doesn't seem like anyone care - if people want room sized SGI machines the Origin is much more sexy (hello Thomas!) :) So maybe it it time to mark SN2 broken and see if anyone screams? Without SN2 the whole machvec mess could basically go away - the only real difference between the remaining machvecs is which iommu if any we set up.
