On 24/03/2020 18:54, Christoph Hellwig wrote: > On Tue, Mar 24, 2020 at 02:05:54PM +1100, Alexey Kardashevskiy wrote: >> This is for persistent memory which you can DMA to/from but yet it does >> not appear in the system as a normal memory and therefore requires >> special handling anyway (O_DIRECT or DAX, I do not know the exact >> mechanics). All other devices in the system should just run as usual, >> i.e. use 1:1 mapping if possible. > > On other systems (x86 and arm) pmem as long as it is page backed does > not require any special handling. This must be some weird way powerpc > fucked up again, and I suspect you'll have to suffer from it. It does not matter if it is backed by pages or not, the problem may also appear if we wanted for example p2p PCI via IOMMU (between PHBs) and MMIO might be mapped way too high in the system address space and make 1:1 impossible. -- Alexey _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
- Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass fla... Greg Kroah-Hartman
- Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass fla... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypas... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: add a dma_ops_b... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: add a dma_o... Aneesh Kumar K.V
- Re: [PATCH 1/2] dma-mapping: add a d... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Aneesh Kumar K.V
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Alexey Kardashevskiy
- Re: [PATCH 1/2] dma-mapping: ad... Christoph Hellwig
- Re: [PATCH 1/2] dma-mapping: add a dma_ops_b... Alexey Kardashevskiy