On Mon, Apr 13, 2026 at 03:34:05PM +0200, Morten Brørup wrote: > > From: David Marchand [mailto:[email protected]] > > Sent: Saturday, 11 April 2026 12.11 > > > > On Fri, 10 Apr 2026 at 16:35, Morten Brørup <[email protected]> > > wrote: > > > > > > Is there a workaround until this patch is added, if I don't want > > rte_eal_init() to probe any devices, but I want my application to probe > > devices later by calling rte_bus_scan() followed by rte_bus_probe()? > > > > > > It's not something we really need, so if you don't know it off the > > top of your head, don't spend time trying to figure it out. > > > > Well, starting from the well known -a pci:0000:00:00.0 trick, I wrote > > an incomplete workaround implemented for OVS. > > https://patchwork.ozlabs.org/project/openvswitch/patch/20260226172429.2 > > [email protected]/ > > > > Incomplete, because some buses make life harder with some additional > > parsing restraints (bus/dpaa is the first one that comes to mind) or > > requiring a driver handling the device exists (bus/platform which has > > *no* in-tree driver, though this is a different story..). > > Thanks for all the input, David. > > In my case it's only PCI bus devices, so I found a relatively simple > workaround instead of using the "-a" trick. > > I start by not binding the devices to the vfio-pci kernel driver. > Then I call rte_eal_init(); and the devices are not detected by the EAL at > this point. > Then I bind the devices to the vfio-pci kernel driver. > And finally I call rte_bus_scan() and rte_bus_probe(); then the devices are > detected at this point. > > Note: I have to pass "--iova-mode pa" to EAL init. > Otherwise EAL init chooses VA mode, causing my drivers to not load, with the > following message: > "PCI_BUS: Expecting 'PA' IOVA mode but current mode is 'VA', not > initializing" > > For anyone following the thread... > > During experimentation, I observed that if the devices were bound to the > vfio-pci kernel driver, and "-a ..." was passed to rte_eal_init() it did - as > expected - not load the drivers. > However, when calling rte_bus_scan() and rte_bus_probe() afterwards, the > drivers were also not auto-detected at this point. > I guess the "-a ..." parameter is sticky, which makes sense. > Yes. The assumption is that, if you don't want to auto-probe, you want to instead add the devices individually, device by device.
/Bruce
