Re: [PATCH v4 2/3] ethdev: add standby state for live migration

[Thomas Monjalon <thomas@monjalon.net>]

31/01/2023 19:14, Jerin Jacob:
> On Wed, Jan 18, 2023 at 9:15 PM Rongwei Liu <rongweil@nvidia.com> wrote:
> >
> > When a DPDK application must be upgraded,
> > the traffic downtime should be shortened as much as possible.
> > During the migration time, the old application may stay alive
> > while the new application is starting and being configured.
> >
> > In order to optimize the switch to the new application,
> > the old application may need to be aware of the presence
> > of the new application being prepared.
> > This is achieved with a new API allowing the user to change the
> > new application state to standby and active later.
> >
> > The added function is trying to apply the new state to all probed
> > ethdev ports. To make this API simple and easy to use,
> > the same flags have to be accepted by all devices.
> >
> > This is the scenario of operations in the old and new applications:
> > .       device: already configured by the old application
> > .       new:    start as active
> > .       new:    probe the same device
> 
> How to probe same device if is already bind to another application?
> vfio-pci wont allow this.

I missed that part.
There is no way to share a VFIO device between 2 applications?


> > .       new:    set as standby
> > .       new:    configure the device
> > .       device: has configurations from old and new applications
> > .       old:    clear its device configuration
> > .       device: has only 1 configuration from new application
> > .       new:    set as active
> > .       device: downtime for connecting all to the new application
> > .       old:    shutdown