On 04/23/2018 08:10 AM, Oleksandr Andrushchenko wrote: > On 04/23/2018 02:52 PM, Wei Liu wrote: >> On Fri, Apr 20, 2018 at 02:25:20PM +0300, Oleksandr Andrushchenko wrote: >>>>> the gntdev. >>>>> >>>>> I think this is generic enough that it could be implemented by a >>>>> device not tied to Xen. AFAICT the hyper_dma guys also wanted >>>>> something similar to this. >>>> You can't just wrap random userspace memory into a dma-buf. We've >>>> just had >>>> this discussion with kvm/qemu folks, who proposed just that, and >>>> after a >>>> bit of discussion they'll now try to have a driver which just wraps a >>>> memfd into a dma-buf. >>> So, we have to decide either we introduce a new driver >>> (say, under drivers/xen/xen-dma-buf) or extend the existing >>> gntdev/balloon to support dma-buf use-cases. >>> >>> Can anybody from Xen community express their preference here? >>> >> Oleksandr talked to me on IRC about this, he said a few IOCTLs need to >> be added to either existing drivers or a new driver. >> >> I went through this thread twice and skimmed through the relevant >> documents, but I couldn't see any obvious pros and cons for either >> approach. So I don't really have an opinion on this. >> >> But, assuming if implemented in existing drivers, those IOCTLs need to >> be added to different drivers, which means userspace program needs to >> write more code and get more handles, it would be slightly better to >> implement a new driver from that perspective. > If gntdev/balloon extension is still considered: > > All the IOCTLs will be in gntdev driver (in current xen-zcopy > terminology): > - DRM_ICOTL_XEN_ZCOPY_DUMB_FROM_REFS > - DRM_IOCTL_XEN_ZCOPY_DUMB_TO_REFS > - DRM_IOCTL_XEN_ZCOPY_DUMB_WAIT_FREE > > Balloon driver extension, which is needed for contiguous/DMA > buffers, will be to provide new *kernel API*, no UAPI is needed. > So I am obviously a bit late to this thread, but why do you need to add new ioctls to gntdev and balloon? Doesn't this driver manage to do what you want without any extensions? -boris _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
