Hi, On Fri, 30 Oct 2015, Christian Borntraeger wrote: > here is the 2nd version of providing an DMA API for s390. > > There are some attempts to unify the dma ops (Christoph) as well > as some attempts to make virtio use the dma API (Andy). > > At kernel summit we concluded that we want to use the same code on all > platforms, whereever possible, so having a dummy dma_op might be the > easiest solution to keep virtio-ccw as similar as possible to > virtio-pci.Together with a fixed up patch set from Andy Lutomirski > this seems to work. > > We will also need a fixup for powerc and QEMU changes to make virtio > work with iommu on power and x86. > > TODO: > - future add-on patches to also fold in x86 no iommu > - dma_mask > - checking? > - make compilation of dma-noop dependent on something > > v1->v2: > - initial testing > - always use dma_noop_ops if device has no private dma_ops > - get rid of setup in virtio_ccw,kvm_virtio > - set CONFIG_HAS_DMA(ATTRS) for virtio (fixes compile for !PCI) > - rename s390_dma_ops to s390_pci_dma_ops > > Christian Borntraeger (3): > Provide simple noop dma ops > alpha: use common noop dma ops > s390/dma: Allow per device dma ops > > arch/alpha/kernel/pci-noop.c | 46 ++-------------------- > arch/s390/Kconfig | 3 +- > arch/s390/include/asm/device.h | 6 ++- > arch/s390/include/asm/dma-mapping.h | 6 ++- > arch/s390/pci/pci.c | 1 + > arch/s390/pci/pci_dma.c | 4 +- > include/linux/dma-mapping.h | 2 + > lib/Makefile | 2 +- > lib/dma-noop.c | 77 +++++++++++++++++++++++++++++++++++++ > 9 files changed, 98 insertions(+), 49 deletions(-) > create mode 100644 lib/dma-noop.c > > -- I agree with these changes in principle. As long as we don't do MMIO (writel and friends) on a dummy mapping we're fine. Regards, Sebastian -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
