On Wed, May 11, 2022 at 05:37:50PM +0300, Mike Rapoport wrote: > Presuming that devices see [0x1000200000-0x103fffffff] as > [0x200000-0x3fffffff] we may try something like > > min = memblock_start_of_DRAM(); > max = min + 0xffffffff; > > if (flags & SWIOTLB_ANY) > max = MEMBLOCK_ALLOC_ACCESSIBLE; > > tlb = memblock_alloc_try_nid(bytes, PAGE_SIZE, min, max, NUMA_NO_NODE); While there is still no guarantee the first 32-bits worth of DRAM are actually mapped to a usable address, this looks like a much better default than what we have right now.
