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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] PV DRM doesn't work without auto_translated_physmap feature in Dom0
On 1/6/20 10:38 AM, Jürgen Groß wrote: > On 06.01.20 08:56, Santucco wrote: >> Hello, >> >> I’m trying to use vdispl interface from PV OS, it doesn’t work. >> Configuration details: >> Xen 4.12.1 >> Dom0: Linux 4.20.17-gentoo #13 SMP Sat Dec 28 11:12:24 MSK 2019 >> x86_64 Intel(R) Celeron(R) CPU N3050 @ 1.60GHz GenuineIntel GNU/Linux >> DomU: x86 Plan9, PV >> displ_be as a backend for vdispl and vkb >> >> when VM starts, displ_be reports about an error: >> gnttab: error: ioctl DMABUF_EXP_FROM_REFS failed: Invalid argument >> (displ_be.log:221) >> >> related Dom0 output is: >> [ 191.579278] Cannot provide dma-buf: use_ptemode 1 >> (dmesg.create.log:123) > > This seems to be a limitation of the xen dma-buf driver. It was written > for being used on ARM initially where PV is not available. This is true and we never tried/targeted PV domains with this implementation, so if there is a need for that someone has to take a look on the proper implementation for PV... > > CC-ing Oleksandr Andrushchenko who is the author of that driver. He > should be able to tell us what would be needed to enable PV dom0. > > Depending on your use case it might be possible to use PVH dom0, but > support for this mode is "experimental" only and some features are not > yet working. > Well, one of the workarounds possible is to drop zero-copying use-case (this is why display backend tries to create dmu-bufs from grants passed by the guest domain and fails because of "Cannot provide dma-buf: use_ptemode 1") So, in this case display backend will do memory copying for the incoming frames and won't touch DMABUF_EXP_FROM_REFS ioctl. To do so just disable zero-copying while building the backend [1] > > Juergen > [1] https://github.com/xen-troops/displ_be/blob/master/CMakeLists.txt#L12 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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