6.2 SHOWSTOPPER - em completely unusable on 6.2

Robert Watson rwatson at FreeBSD.org
Sat Sep 30 02:11:08 PDT 2006

On Sat, 30 Sep 2006, Scott Long wrote:

> David G Lawrence wrote:
>>>>   Attached is a simple user program that will immediately cause pretty 
>>>> much
>>>> all of the network drivers (at least the ones I own) to stop working and
>>>> get watchdog timeouts.
>>> I am runnign this on a single processor machine with an SMP kernel and
>>> it does not have any effect. I dont tink I have any single processor 
>>> machines
>>> running a non SMP kernel to try it on though. Not particularly helpful I 
>>> know. I'll
>>    Actually, I think it is helpful to know that the program only has an 
>> effect on some machines. We just need to figure out what the common 
>> denominator is.
> Are you enabling an option, like IPv6, that puts Giant over the network 
> stack?

IPv6 has Giant over its netisr, but not over the entire network stack.  If 
Giant is being placed over the stack due to use of an option that forces it 
(such as KAME IPSEC) you should be able to grep this out of dmesg by doing 
something along the lines of the following:

     grep "WARNING: debug.mpsafenet" /var/run/dmesg

Robert N M Watson
Computer Laboratory
University of Cambridge

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