svn commit: r205024 - head/sys/net

[Julian Elischer]

Julian Elischer wrote:
> Robert N. M. Watson wrote:

>>>>
>>>> Today, we support three link state values:
>>>>
>>>> 170 /*
>>>> 171  * Values for if_link_state.
>>>> 172  */
>>>> 173 #define LINK_STATE_UNKNOWN      0       /* link invalid/unknown */
>>>> 174 #define LINK_STATE_DOWN         1       /* link is down */
>>>> 175 #define LINK_STATE_UP           2       /* link is up */
>>>>
>>>> I'm confused about Julian's proposal because it seems to me that we 
>>>> already know when a driver hasn't set or is unable to determine the 
>>>> link state: it will (should) be set to LINK_STATE_UNKNOWN by default.

the question is whether there is any other meaning for this state.
For example "I have not started up yet"

>>>>
>>>> So the only question we don't know the answer to, at run-time, is 
>>>> whether a driver may *ever* set the link state (i.e., it thinks it 
>>>> knows how to), and hence whether or not tools like dhclient should 
>>>> try to wait for that to happen. That is the problem that an 
>>>> interface capability would solve.
>>>>
>>>> For the purposes of ECMP, you just need to decide on your policy: 
>>>> map UNKNOWN to either UP or DOWN for your purposes.

yes
this is a good approach assuming that there is no other meaning.


>>>>
>>>> Robert