Messages in this thread | | | Date | Wed, 24 Apr 2019 16:23:01 -0700 (PDT) | Subject | Re: [PATCH 0/7] RISC-V: Sparsmem, Memory Hotplug and pte_devmap for P2P | From | Palmer Dabbelt <> |
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On Wed, 27 Mar 2019 14:36:36 PDT (-0700), logang@deltatee.com wrote: > Hi, > > This patchset enables P2P on the RISC-V architecture. To do this on the > current kernel, we only need to be able to back IO memory with struct > pages using devm_memremap_pages(). This requires ARCH_HAS_ZONE_DEVICE, > ARCH_ENABLE_MEMORY_HOTPLUG, and ARCH_ENABLE_MEMORY_HOTREMOVE; which in > turn requires ARCH_SPARSEMEM_ENABLE. We also need to ensure that the > IO memory regions in hardware can be covered by the linear region > so that there is a linear relation ship between the virtual address and > the struct page address in the vmemmap region. > > While our reason to do this work is for P2P, these features are all > useful, more generally, and also enable other kernel features. > > The first patch in the series implements sparse mem. It was already > submitted and reviewed last cycle, only forgotten. It has been rebased > onto v5.1-rc2. > > Patches 2 through 4 rework the architecture's virtual address space > mapping trying to get as much of the IO regions covered by the linear > mapping. With Sv39, we do not have enough address space to cover all the > typical hardware regions but we can get the majority of it. > > Patch 5 and 6 implement memory hotplug and remove. These are relatively > straight forward additions similar to other arches. > > Patch 7 implements pte_devmap which allows us to set > ARCH_HAS_ZONE_DEVICE. > > The patchset was tested in QEMU and on a HiFive Unleashed board. > However, we were unable to actually test P2P transactions with this > exact set because we have been unable to get PCI working with v5.1-rc2. > We were able to get it running on a 4.19 era kernel (with a bunch of > out-of-tree patches for PCI on a Microsemi PolarFire board). > > This series is based on v5.1-rc2 and a git tree is available here: > > https://github.com/sbates130272/linux-p2pmem riscv-p2p-v1
Looks like these don't build on rv32 when applied on top of 5.1-rc6. We now have rv32_defconfig, which should make it easier to tests these sorts of things.
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