NAME
ec —
driver for 3Com EtherLink II
(3c503) ISA bus Ethernet cards
SYNOPSIS
ec0 at isa? port 0x250 iomem 0xd8000 irq 9
DESCRIPTION
The
ec device driver supports 3Com EtherLink II (3c503)
Ethernet cards for ISA bus which are based on the National Semiconductor
DP8390/WD83C690 Ethernet interface chips.
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 transceiver.
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 IRQ values was specified in the kernel
configuration file. The EtherLink II hardware only supports the above
listed IRQ values.
- 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 incoming 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 sometimes 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 occasionally overrun.
When an overrun occurs, the board must be reset to avoid a lockup problem in
early revision DP8390 Ethernet chips. Resetting the board causes all of
the data in the ring-buffer to be lost, requiring the data to be
retransmitted/received, congesting the board further. Because of this,
maximum throughput on these boards is only about 400-600K bytes per
second.
This problem is exacerbated by NFS because the 8-bit boards lack sufficient
packet buffer 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 mount_nfs(8)
-r and -w options in
/etc/fstab to limit NFS's packet size. 4K (4096) byte
packets generally work.
SEE ALSO
ifmedia(4),
intro(4),
isa(4),
ifconfig(8),
mount_nfs(8)