> > > > In fact I should have looked more closely at that myself - checking > > debugfs on my 4GB arm64 board actually shows io_tlb_nslabs = 0, and > > indeed we are bypassing initialisation completely and (ab)using > > SWIOTLB_NO_FORCE to cover it up, so I guess it probably *is* safe now > > for the noforce option to do the same for itself and save even that one > > page. > > OK, I can submit a patch that does that. 5.12-rc3 works correctly for me > here as well and only allocates SWIOTLB when needed which in our case is > either: > > - we have DRAM at PA >= 4GB > - we have limited peripherals (Raspberry Pi 4 derivative) that can only > address the lower 1GB > > Now let's see if we can get ARM 32-bit to match :)
Whatever patch you come up with, if it is against SWIOTLB please base it on top of devel/for-linus-5.12 in https://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git/ Thx > -- > Florian
