I will be replying here instead of replying to each and every msg :) On 28-06-21, 16:58, Wolfram Sang wrote: > > > You can fine Viresh's vhost-user implementation at > > https://lore.kernel.org/qemu-devel/cover.1617278395.git.viresh.kumar@xxxxxxxxxx/t/#m3b5044bad9769b170f505e63bd081eb27cef8db2 > > It looks OK so far; yet, it is not complete. But it might be bearable > in the end. While we are at it, this has been replaced by a Rust counterpart [1] (as that makes it hypervisor agnostic, which is the goal of my work here) and I need someone with I2C knowledge to help review it. It should be okay even if you don't understand Rust a lot, just review this file[2] which is where most of i2c specific stuff lies. > > As you say, it does get a bit clumsy, but I think there is also a good argument > > to be made that the clumsiness is based on the host Linux user interface > > more than the on the requirements of the physical interface, > > and that should not have to be reflected in the virtio specification. > > Makes sense to me. > > > Right, this one has come up before as well: the preliminary result > > was to assume that this probably won't be needed, but would be easy > > enough to add later if necessary. > > If adding support incrementally works for such an interface, this makes > sense as well. Yes, we don't support few of SMBUS transaction (the block ones) as you specified. > So, where are we? The virtio specification is already merged and here is the latest version [3]. > As I understand, this v10 does not support I2C transactions (or > I2C_RDWR as you said). I am not sure why you say I2C_RDWR isn't supported. The spec and Linux driver (+ my Rust/qemu backend), they all support I2C_RDWR as well as SMBUS. To clarify on an earlier point, every virtio transfer may contain one or more struct i2c_msg instances, all processed together (as expected). If you see virtio_i2c_send_reqs() in this patch, you will see that it converts a stream of i2c_req messages to their virtio counterparts and send them together, consider it a single transaction. > But you want to support all clients. So, this doesn't match, or? -- viresh [1] https://github.com/rust-vmm/vhost-device/pull/1 [2] https://github.com/rust-vmm/vhost-device/blob/5aa22c92faac84ab07b6b15a214513556e8b1d01/src/i2c/src/i2c.rs [3] https://github.com/oasis-tcs/virtio-spec/blob/master/virtio-i2c.tex
