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To: Alan Cox <alc@cs.rice.edu>
cc: hardware@FreeBSD.org
Subject: Re: Intel Pro/100B 
In-reply-to: Your message of "Sat, 04 May 1996 11:14:35 CDT."
             <199605041614.LAA01487@noel.cs.rice.edu> 
From: David Greenman <davidg@Root.COM>
Reply-To: davidg@Root.COM
Date: Sat, 04 May 1996 10:27:11 -0700
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>Can someone with the documentation for this card please tell me how
>to increase the interpacket gap on transmission?
>
>In case you're curious, the background is that I'm using several FreeBSD
>powered machines with the Pro/100B (and some SPARC 20s too) to evaluate
>a Cisco 1700 and a Cisco 5000 with a 10/100 switching module.  Under load,
>the Cisco 1700 is flashing an LED that among other things indicates
>babble on the port.  With the SPARC 20s driving the network, I don't see
>this problem.

   This is likely caused by the motherboard that contains the 100B not having
adequate PCI throughput for some reason, causing the DMA to get aborted in
the middle of a transmit. Try the following patch and let me know if it helps.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project

Index: if_fxp.c
===================================================================
RCS file: /home/ncvs/src/sys/pci/if_fxp.c,v
retrieving revision 1.8.2.2
diff -c -r1.8.2.2 if_fxp.c
*** if_fxp.c	1996/04/08 01:31:59	1.8.2.2
--- if_fxp.c	1996/05/04 17:26:17
***************
*** 490,496 ****
  	txp->cb_status = 0;
  	txp->cb_command =
  	    FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF | FXP_CB_COMMAND_S;
! 	txp->tx_threshold = 16;	/* bytes*8 */
  	txp->mb_head = mb_head;
  	
  	/*
--- 490,496 ----
  	txp->cb_status = 0;
  	txp->cb_command =
  	    FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF | FXP_CB_COMMAND_S;
! 	txp->tx_threshold = 128;	/* bytes*8 */
  	txp->mb_head = mb_head;
  	
  	/*