hyperv/hn: Add sysctl to trust host side UDP and IP csum verification

[honzhan_microsoft.com]

sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

531 ↗

(On Diff #12782)

I saw some SYSCTL was added in if (unit == 0), others are not. What is the reason?

[sepherosa_gmail.com]

sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

531 ↗

(On Diff #12782)

This set is added to the devclass tree, i.e. dev.hn; while the above set is added to dev.hn.X. The sysctl nodes under devclass tree is used to give users a convenient way to check the values of the tunables w/ the same name, as suggested by delphij.

[adrian]

sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

531 ↗

(On Diff #12782)

Hm, I thought we did "hw.XXX" for device specific things in freebsd, versus unit-specific things (which is dev.XXX.unit.)

-a

[sepherosa_gmail.com]

sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

531 ↗

(On Diff #12782)

Nah, they are read-only nodes for the devclass tunables, i.e. dev.hn.XXX, not dev.hn.unit.XXX.

As about why we need to create the sysctl nodes dynamically: the devclass sysctl tree is created dynamically by bus code, so the static RDTUN sysctl definition will not work for dev.hn.

[adrian]

So this is okay, but we put the non-unit bits under 'hw', not 'dev'. Ie, it'd be dev.XXX.0.stuff, and hw.XXX.stuff.

So I'll okay this, but we should eventually shuffle them back to 'hw'.