From: Stephen Hemminger > wrote: > > > Hi > > > > From: Stephen Hemminger > > > The vdev_netvsc virtual driver that is used to do initialization on > > > Hyper- V/Azure won't work without failsafe and tap device. > > > If the related devices aren't present, it causes confusing errors > > > later in initialization when it crafts devargs and attempts to send > > > them to a device driver that isn't there. > > > > > > Unfortunately, this is common with VPP where the TAP and FAILSAFE > > > PMD's are both optional. The suggestion here is to detect this in > > > the startup phase earlier. > > > > > > Alternative would be to use RTE_BUILD_BUG_ON(!defined(...)) but that > > > would break people doing normal VPP build. > > > > > > > The failsafe and tap devices are created by the vdev_netvsc PMD, so it is > not expected to find them in the scan time. > > If the VM doesn't want vdev_netvsc driver to run, it have 2 options: > > 1. assign IP to the netvsc netdevs. > > 2. run --vdev="vdev_netvsc0,ignore=1" - see documentation for more info. > > > > > How do we improve the error reporting for configurations that have run > Hyper-V/Azure but forget to build failsafe, tap or mlx5 device drivers. Right > now the error messages are confusing, misleading and waste significant > amount of developer time. > > What solution do you propose? The DPDK build system is not as smart as > kernel Kconfig, there is no way to force dependencies. Why? Can't you condition the vdev_netvsc compilation in failsafe and tap compilation? 1 more option: To condition the vdev_netvsc automated probing (in vdev_netvsc_custom_scan_add) by "ifdef" statement in failsafe and tap compilation existence. Moreover, you can add clearer massage for this case if vdev_netvsc is running (vdev_netvsc_vdev_probe). Matan.