docs/88477: Possible addition to xl(4) manpage, Diagnostics section

[Reko Turja]

>Number:         88477
>Category:       docs
>Synopsis:       Possible addition to xl(4) manpage, Diagnostics section
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Fri Nov 04 02:10:15 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Reko Turja
>Release:        6.0 STABLE
>Organization:
>Environment:
FreeBSD muppet.liukuma.net 6.0-STABLE FreeBSD 6.0-STABLE #7: Wed Nov  2 23:17:37 EET 2005     root at muppet.liukuma.net:/usr/obj/usr/src/sys/LIUKUMA  i386

>Description:
The 3com xl-series of adapters usually emit some messages like:

+xl0: transmission error: 90
+xl0: tx underrun, increasing tx start threshold to 180 bytes
+xl0: transmission error: 90
+xl0: tx underrun, increasing tx start threshold to 240 bytes
+xl0: transmission error: 90
+xl0: tx underrun, increasing tx start threshold to 300 bytes         

when the interface tunes itself.

Although usually harmless, I think the messages could/should be documented in the xl manpage
>How-To-Repeat:
Give network adapter using the xl(4) driver some workload
>Fix:
There might be some other underlying technical snags with this one (I guess if these messages appear constantly and tx treshold goes over some value the adapter is broken...), but I'd suggest the following: 

Add another entry under diagnostics (maybe as the last one):

xl%d: transmission error: 90
xl%d: tx underrun, increasing tx start threshold to xxx bytes
This message may appear while the adapter tunes it's transmission buffers under load. If these messages won't appear constantly but only soon after reboot, or during heavy network load spikes, they can be probably ignored.
>Release-Note:
>Audit-Trail:
>Unformatted: