On Tue, Dec 10, 2024 at 11:51 PM Eugenio Perez Martin <epere...@redhat.com> wrote: > > On Thu, Dec 5, 2024 at 9:17 AM Jason Wang <jasow...@redhat.com> wrote: > > > > Adding Eugenio and YongJi. > > > > On Wed, Dec 4, 2024 at 11:38 PM <t.ampelikio...@virtualopensystems.com> > > wrote: > > > > > > From: Timos Ampelikiotis <t.ampelikio...@virtualopensystems.com> > > > > > > We would like to share with you an RFC for the Virtio-loopback > > > technology which we have been working on at Virtual Open Systems in > > > the context of the Automotive Grade Linux community (Software defined > > > Vehicles expert group) > > > > > > We previously presented this activity (see [1]) and now we come back > > > to you with latest development and updates. > > > > > > We believe that the technology is more mature today and we would like > > > to assess the community interest in the technology itself and in > > > merging the code. > > > > > > Below we provide a brief description of the technology, recent > > > updates and a short comparison with vDUSE that might be seen as a > > > similar technology. > > > > > > 1. Overview: > > > ------- > > > > > > Virtio-loopback is a hardware abstraction layer (HAL) designed for > > > non-virtualized environments based on virtio. The main objective is > > > to enable applications communication with vhost-user devices in a > > > non-virtualized environment. > > > > > > More in details, Virtio-loopback architecture consists of a new > > > transport (Virtio-loopback), a user-space application (Adapter) and > > > the vhost-user devices. > > > > > > The data path has been implemented using the "zero-copy" principle, > > > > [ ... ] > > > > > where vhost-user devices access virtqueues directly in the kernel > > > space. > > > > Eugenio used to work on a POC to bridge vhost-user to vDPA via a > > dedicated userspace application. He might share more thoughts about > > this. > > > > Right, it worked well with DPDK and net. It could work as long as > vhost-user device supported iotlb messages. > > The current kernel vdpa framework does not send the memory map until > the device asks for it. If we modify the kernel vdpa so it always > sends the memory map, and only waits for the userland device iotlb if > a given feature flag is negotiated, it can be compatible with all the > vhost-user devices.
This seems feasible and not very hard, and we can only allow such notification while userspace wants it by a new flag probably. > > I can post the code if it is useful for sure. > Thanks
