On Sat, Feb 17, 2024 at 11:51:14PM -0800, Saurabh Singh Sengar wrote: > On Sun, Feb 18, 2024 at 08:10:36AM +0100, Greg KH wrote: > > On Sat, Feb 17, 2024 at 10:03:34AM -0800, Saurabh Sengar wrote: > > > Hyper-V is adding multiple low speed "speciality" synthetic devices. > > > Instead of writing a new kernel-level VMBus driver for each device, > > > make the devices accessible to user space through UIO-based > > > uio_hv_generic driver. Each device can then be supported by a user > > > space driver. This approach optimizes the development process and > > > provides flexibility to user space applications to control the key > > > interactions with the VMBus ring buffer. > > > > > > The new synthetic devices are low speed devices that don't support > > > VMBus monitor bits, and so they must use vmbus_setevent() to notify > > > the host of ring buffer updates. These new devices also have smaller > > > ring buffer sizes which requires to add support for variable ring buffer > > > sizes. > > > > > > Moreover, this patch series adds a new implementation of the fcopy > > > application that uses the new UIO driver. The older fcopy driver and > > > application will be phased out gradually. Development of other similar > > > userspace drivers is still underway. > > > > > > > > > Efforts have been made previously to implement this solution earlier. > > > Here are the discussions related to those attempts: > > > https://lore.kernel.org/lkml/1691132996-11706-1-git-send-email-ssengar@xxxxxxxxxxxxxxxxxxx/ > > > https://lore.kernel.org/lkml/1665575806-27990-1-git-send-email-ssengar@xxxxxxxxxxxxxxxxxxx/ > > > https://lore.kernel.org/lkml/1665685754-13971-1-git-send-email-ssengar@xxxxxxxxxxxxxxxxxxx/ > > > > So is this a v4 of the patch series? What has changed from those > > previous submissions? > > In the most recent attempt we introduced a new driver uio_hv_vmbus_client > for slow devices, where as in this new approach we are making use of > existing uio_hv_generic driver. > > We also introduced the function to query ring buffer sizes, this is an > attempt to address your comment on earlier series to avoid kernel params. > Comment ref: https://lore.kernel.org/lkml/Y0bipdisMbTNMYOq@xxxxxxxxx/ > > We later tried to have ring buffer sizes via sysfs for which we wrote a > new driver uio_hv_vmbus_client as explained above. > > This is the next approach in an attempt to address all of the concerns > with all the previous series. Then you need to say that somewhere, what differs from the previous submissions and why this is better. Remember, some of us get 1000+ emails a day to do something with, and trying to remember a review comment from last week, let alone months ago, is impossible. Make this easy for us please... And as this is a "next approach", it should be versioned properly. What would you want to see if you had to review this? thanks, greg k-h
