Shell copy_file() issue with NFS and small MAC receive buffer

Chris Johns chrisj at
Fri Apr 1 00:28:58 UTC 2011

On 1/04/11 11:22 AM, Kirspel, Kevin wrote:
> The problem is the number of 1500 byte fractional packets sent over by the NFS server at one time.  8192 / 1500 = 6 fractional packets (sent one after the other).  This causes my receive buffer to fill up before the packets can be processed.  To solve this problem, the NFS client in RTEMS has a global variable named nfsStBlksize.  This limits the number of fractional packets that the NFS server can send before looking for the ack packet.  In my case, 4096 / 1500 = 3 fractional packets which can be handled by the receive buffer. Various Ethernet MACs have different buffer sizes which is why you probably did not see the issue.

Changing the NFS buffer size would seem to be a work around.

What happens if something sends a number of broadcast packets on to your 
subnet or ping packets at the same time to your target ?


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