On Tue, Jan 24, 2017 at 08:42:23PM +0530, Sricharan wrote: > Thanks for this series. We had a case with the GPU. > The GPU's iommu was setup by kernel and the GPU > also does dynamic updates for on-the-fly switching between > process pagetables. GPU driver was not using DMA domain and > the GPU's firmware was always expecting to run out of contextbank > '0' (although not correct) , which was not the case after the DMA domain > was made default as '0' was getting allocated for DMA domain and > there were concerns about reusing the DMA domain as well. > Now with this series, looks there is an way out of that that can be tried. > > So should the default domain not be per device specific selectable ?
Note that iommu-drivers can request direct-mapping for any given device on its initializtion. This is used on x86 for devices that need a 1-1 mapping for some reason. Also device drivers can use the iommu-api and assign their own domain to a device, which allows them to manage the dma address space on their own. Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu