On Fri, Aug 07, 2020 at 10:50:19AM +0200, Nicolas Saenz Julienne wrote: > On Fri, 2020-08-07 at 07:21 +0200, Christoph Hellwig wrote: > > On Thu, Aug 06, 2020 at 08:47:55PM +0200, Nicolas Saenz Julienne wrote: > > > There is no guarantee to CMA's placement, so allocating a zone specific > > > atomic pool from CMA might return memory from a completely different > > > memory zone. To get around this double check CMA's placement before > > > allocating from it. > > > > As the builtbot pointed out, memblock_start_of_DRAM can't be used from > > non-__init code. But lookig at it I think throwing that in > > is bogus anyway, as cma_get_base returns a proper physical address > > already. > > It does indeed, but I'm comparing CMA's base with bitmasks that don't take > into > account where the memory starts. Say memory starts at 0x80000000, and CMA > falls > into ZONE_DMA [0x80000000 0xC0000000], if you want to compare it with > DMA_BIT_MASK(zone_dma_bits) you're forced to unify the memory bases. > > That said, I now realize that this doesn't work for ZONE_DMA32 which has a > hard > limit on 32bit addresses reglardless of the memory base. > > That said I still need to call memblock_start_of_DRAM() any suggestions WRT > that? I could save the value in dma_atomic_pool_init(), which is __init code.
The pool must be about a 32-bit physical address. The offsets can be different for every device.. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
