On Mon, Mar 20, 2017 at 1:18 PM, Oleksandr Andrushchenko <andr2...@gmail.com> wrote: > > > On 03/18/2017 02:22 PM, Rob Clark wrote: >> >> On Fri, Mar 17, 2017 at 1:39 PM, Oleksandr Andrushchenko >> <andr2...@gmail.com> wrote: >>> >>> Hello, >>> I am writing a para-virtualized DRM driver for Xen hypervisor >>> and it now works with DRM CMA helpers, but I would also like >>> to make it work with non-contigous memory: virtual machine >>> that the driver runs in can't guarantee that CMA is actually >>> physically contigous (that is not a problem because of IPMMU >>> and other means, the only constraint I have is that I cannot mmap >>> with pgprot == noncached). So, I am planning to use *drm_gem_get_pages* + >>> *shmem_read_mapping_page_gfp* to allocate memory for GEM objects >>> (scanout buffers + dma-bufs shared with virtual GPU) >>> >>> Do you think this is the right approach to take? >> >> I guess if you had some case where you needed to "migrate" buffers >> between host and guest memory, then TTM might be useful. Otherwise >> this sounds like the right approach. > > Tried that today (drm_gem_get_pages), the result is interesting: > > 1. modetest > 1.1. Runs, I can see page flips > 1.2. vm_operations_struct.fault is called, I can vm_insert_page > > 2. kmscube (Rob, thanks for that :) + PowerVR SGX 6250 > 2.1. Cannot initialize EGL > 2.2. vm_operations_struct.fault is NOT called
jfwiw, pages will only get faulted in when CPU accesses them.. modetest "renders" the frame on the CPU but kmscube does it on gpu. So not seeing vm_operations_struct.fault is normal. The EGL fail is not.. > In both cases 2 dumbs are created and successfully mmaped, > in case of kmscube there are also handle_to_fd IOCTLs issued > and no DRM errors observed. No DMA-BUF mmap attempt seen > > I re-checked 2) with alloc_pages + remap_pfn_range and it works > (it cannot unmap cleanly, but it could be because I didn't call > split_pages after alloc_pages), thus the setup is still good > > Can it be that the buffer allocated with drm_gem_get_pages > doesn't suit PowerVR for some reason? I've no idea what the state of things is w/ pvr as far as gbm support (not required/used by modetest, but anything that uses the gpu on "bare metal" needs it). Or what the state of dmabuf-import is with pvr. BR, -R >> >> >> BR, >> -R > > Thank you, > Oleksandr _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
