kern/46083: gem(4) is broken on NetBSD 6_BETA (macppc)

[kretschm%cs.uni-bonn.de@localhost]

>Number:         46083
>Category:       kern
>Synopsis:       gem(4) is broken on NetBSD 6_BETA (macppc)
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 23 18:45:00 +0000 2012
>Originator:     Matthias Kretschmer
>Release:        NetBSD 6_BETA macppc
>Organization:
>Environment:
NetBSD blavet.barock.local 6.0_BETA NetBSD 6.0_BETA (BLAVET) #1: Mon Feb 20 
13:58:05 CET 2012  
matthias@telemann.barock.local:/var/itch/netbsd6/obj/var/itch/netbsd6/src/sys/arch/macppc/compile/BLAVET
 macppc
>Description:
gem(4) is broken NetBSD 6_BETA (on macppc)

The gem(4) interface on the iBook does not work properly anymore with 6_BETA.  
On 5.1_STABLE from some months ago it works like a charm.  When having network 
usage, the interface somehow gets in an unusable state which hangs the system.  
This is a critical problem for me, as the gem(4) interface is my primary 
network interface and I often boot this box from network for testing purposes.  
On 5.1_STABLE I do not have such problems at all.

When I'm lucky, I see a "gem0: device timeout" kernel message.  Sometimes I 
don't even see this.

When booting from network, sometimes it stops while processing the init 
scripts, sometimes I can log in before it hangs.  Keyboard input is processed 
(I can read what I type on console), but processes are stalled.
>How-To-Repeat:
Boot the box from network or generate a lot of network traffic by for example 
extracting a big source tarball on NFS.
>Fix: