On 04/30/2018 04:24 PM, Andrew Lunn wrote:

quoted

Turning these tests on will typically result in the link partner
dropping the link with us, and the interface will be non-functional as
far as the data path is concerned (similar to an isolation mode). This
might warrant properly reporting that to user-space through e.g: a
private IFF_* value maybe?

Hi Florian

I think a IFF_* value would be a good idea. We want to give the user
some indicate why they don't have working networking. ip link show
showing PHY-TEST-MODE would help.

IF_OPER_TESTING as defined in RFC 2863 looks like the correct way to
signal that. I did a quick test and setting operstate to
IFF_OPER_TESTING seems to correctly get reflected by iproute2/ifconfig
which no longer see RUNNING though the interface is still UP. If we
couple that with a proper phy_stop(), this would IMHO be consistent from
an user experience perspective.

David, would that look reasonable to you?
-- 
Florian