On Mon, Oct 14, 2019 at 01:38:34PM -0700, Linus Torvalds wrote: > And now I've said pgd/pud/p4d/pmd so many times that I've confused > myself and think I'm wrong again, and I think that historically - > originally - we always had a pgd, and then the pmd didn't exist > because it was folded into it. That makes sense from a x86 naming > standpoint. Then x86 _did_ get a pmd, and then we added more levels in > between, and other architectures did things differently. Oh my goodness. Thank you for writing all this out and finally getting to this point. I was reading the whole thing thinking "This is different from what I remember" and then you got here. This explains so much about how our MM does/doesn't work, and it's not just me that's confused ;-)