ec(4)
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EC(4) NetBSD Programmer's Manual EC(4)
NAME
ec - device driver for 3Com Etherlink II (3c503) Ethernet cards
SYNOPSIS
ec0 at isa? port 0x250 iomem 0xd8000 irq 9
DESCRIPTION
The ec device driver supports 3Com Etherlink II (3c503) Ethernet cards.
MEDIA SELECTION
The Etherlink II supports two media types on a single card. All support
the AUI media type. The other media is either BNC or UTP behind a tran-
sciever. Software cannot differentiate between BNC and UTP cards.
To enable the AUI media, select the 10base5 or aui media type with
ifconfig(8)'s `media' directive. To select the other media (BNC or UTP),
select the 10base2 or bnc media type.
DIAGNOSTICS
ec0: wildcarded IRQ is not allowed The IRQ was wildcarded in the kernel
configuration file. This is not supported.
ec0: invalid IRQ <n>, must be 3, 4, 5, or 9 An IRQ other than the above
listed IRQs was specified in the kernel configuration file. The Ether-
link II hardware only supports the above listed IRQs.
ec0: failed to clear shared memory at offset <off> The memory test was
unable to clear shared the interface's shared memory region. This often
indicates that the card is configured at a conflicting iomem address.
ec0: warning - receiver ring buffer overrun The DP8390 Ethernet chip
used by this board implements a shared-memory ring-buffer to store incom-
ing packets.
The 3c503 usually has only 8k bytes of shared memory. This is only
enough room for about 4 full-size (1500 byte) packets. This can some-
times be a problem, especially on the original 3c503, because these
boards' shared-memory access speed is quite slow; typically only about
1MB/second. The overhead of this slow memory access, and the fact that
there is only room for 4 full-sized packets means that the ring-buffer
will occassionally overrun. When this happens, the board must be reset
to avoid a lockup problem in early revision 8390's. Resetting the board
causes all of the data in the ring-buffer to be lost, requiring it to be
retransmitted/received, congesting the board further. Because of this,
maximum throughput on these boards is only about 400-600k per second.
This problem is exasperated by NFS because the 8bit boards lack suffi-
cient memory to support the default 8k byte packets that NFS and other
protocols use as their default. If these cards must be used with NFS,
use the NFS -r and -w options in /etc/fstab to limit NFS's packet size.
4096k byte packets generally work.
SEE ALSO
ifmedia(4), intro(4), isa(4), ifconfig(8)
NetBSD 1.4 October 20, 1997 1
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