Subject: Re: gem (ERI/GEM/GMAC Ethernet device driver) has problems on macppc -current
To: Timo Schoeler <>
From: Steven M. Bellovin <>
List: current-users
Date: 10/21/2005 04:23:48
In message <>, Timo Schoeler writes:
>Steven M. Bellovin wrote:
>> In message <>, Timo Schoeler writes:
>>>i said on a plain dumb SMC 10/100 _hub_ this problem appears. then i 
>>>tried the Nortel 450 (_switch) -- this runs fine in full duplex mode. 
>>>when i then manually set both the switch (managed) and the G4 to half 
>>>duplex, the problem occurs again.
>>>when using the SMC _hub_ the machine automatically sets the NIC to half 
>>>duplex as it should be.
>> In other words, whenver your machine is supposed to use half-duplex, 
>> you get these failures, whether the setting is manual or automatic.  I 
>> don't know if it's a bug in the chip or the driver, though.  I don't 
>> recall all of the details of this thread, but how do other OSs behave?  
>> Do any succeed in such a situation? If so, it's probably a driver bug.
>> 		--Steven M. Bellovin,
>neither Mac OS 'Classic' nor Mac OS X show those errors (for the former 
>one i have to check on the switch for CRC errors etc.). NetBSD is the 
>only OS having trouble with this.
I think we've diagnosed the problem to some extent.  I can't help any 
more, since I know nothing of this board or PPCs.  I suggest you 
send-pr, including this analysis -- that it's a collision problem in 
half-duplex mode, manual or automatic -- and hope that someone who does 
know that NIC can help.

		--Steven M. Bellovin,