On Mon, Sep 26, 2022 at 09:32:40PM +0300, Dmitry Osipenko wrote: > On 9/23/22 15:32, Gerd Hoffmann wrote: > > On Tue, Sep 13, 2022 at 12:50:22PM +0200, Antonio Caggiano wrote: > >> From: Dmitry Osipenko <dmitry.osipe...@collabora.com> > >> > >> Host blobs don't need udmabuf, it's only needed by guest blobs. The host > >> blobs are utilized by the Mesa virgl driver when persistent memory mapping > >> is needed by a GL buffer, otherwise virgl driver doesn't use blobs. > >> Persistent mapping support bumps GL version from 4.3 to 4.5 in guest. > >> Relax the udmabuf requirement. > > > > What about blob=on,virgl=off? > > > > In that case qemu manages the resources and continued to require > > udmabuf. > > The udmabuf is used only by the blob resource-creation command in Qemu. > I couldn't find when we could hit that udmabuf code path in Qemu because > BLOB_MEM_GUEST resource type is used only by crosvm+Venus when crosvm > uses a dedicated render-server for virglrenderer.
Recent enough linux guest driver will use BLOB_MEM_GUEST resources with blob=on + virgl=off > - /dev/udmabuf isn't accessible by normal user > - udmabuf driver isn't shipped by all of the popular Linux distros, > for example Debian doesn't ship it That's why blob resources are off by default. > Because of all of the above, I don't think it makes sense to > hard-require udmabuf at the start of Qemu. It's much better to fail > resource creation dynamically. Disagree. When virgl/venus is enabled, then yes, qemu would let virglrenderer manage resources and I'm ok with whatever requirements virglrenderer has. When qemu manages resources by itself udmabuf is a hard requirement for blob support though. take care, Gerd
