| 1 | .\" |
| 2 | .\" |
| 3 | .\" Copyright (c) 1997 Joerg Wunsch |
| 4 | .\" |
| 5 | .\" All rights reserved. |
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| 16 | .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR |
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| 18 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 19 | .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 20 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 27 | .\" $FreeBSD: src/share/man/man4/man4.i386/rdp.4,v 1.5.2.4 2001/08/17 13:08:46 ru Exp $ |
| 28 | .\" $DragonFly: src/share/man/man4/man4.i386/rdp.4,v 1.4 2007/05/17 08:19:01 swildner Exp $ |
| 29 | .\" |
| 30 | .\" |
| 31 | .\" " (emacs disconfusion) |
| 32 | .Dd December 21, 1998 |
| 33 | .Dt RDP 4 i386 |
| 34 | .Os |
| 35 | .Sh NAME |
| 36 | .Nm rdp |
| 37 | .Nd Ethernet driver for RealTek RTL 8002 pocket ethernet |
| 38 | .Sh SYNOPSIS |
| 39 | .Cd "device rdp0 at isa? port 0x378 irq 7" |
| 40 | .Cd "device rdp0 at isa? port 0x378 irq 7 flags 0x2" |
| 41 | .Sh DESCRIPTION |
| 42 | The |
| 43 | .Nm |
| 44 | device driver supports RealTek RTL 8002-based pocket ethernet adapters, |
| 45 | connected to a standard parallel port. |
| 46 | .Pp |
| 47 | These adapters seem to belong to the cheaper choices among pocket |
| 48 | ethernet adapters. The RTL 8002 is the central part, containing an |
| 49 | interface to BNC and UTP (10 Mbit/s) media, as well as a host |
| 50 | interface that is designed to talk to standard parallel printer |
| 51 | adapters. For the full ethernet adapter to work, it is completed by |
| 52 | an external RAM used as the Tx and Rx packet buffer (16 K x 4 for the |
| 53 | RTL 8002), and an EEPROM to hold the assigned ethernet hardware |
| 54 | address. For the RTL 8002, the EEPROM can be either a standard 93C46 |
| 55 | serial EEPROM (which seems to be a common choice), or a 74S288 |
| 56 | parallel one. The latter variant needs the device configuration flag |
| 57 | 0x1 in order to work. |
| 58 | .Pp |
| 59 | Since standard printer adapters seem to vary wildly among their timing |
| 60 | requirements, there are currently two possible choices for the way |
| 61 | data are being exchanged between the pocket ethernet adapter and the |
| 62 | printer interface. The default is the fastest mode the RTL 8002 |
| 63 | supports. If the printer adapter to use is particularly slow (which |
| 64 | can be noticed by watching the ethernet wire for crippled packets, or |
| 65 | by not seeing correctly received packets), the configuration flag 0x2 |
| 66 | can be set in order to throttle down the |
| 67 | .Nm |
| 68 | driver. Note that in fast mode, the data rate is asymmetric, sending |
| 69 | is a little faster (up to two times) than receiving. Rates like 150 |
| 70 | KB/s for sending and 80 KB/s for receiving are common. For slow mode, |
| 71 | both rates are about the same, and in the range of 50 KB/s through 70 |
| 72 | KB/s. As always, your mileage may vary. |
| 73 | .Pp |
| 74 | In case the adapter isn't recognized at boot-time, setting the |
| 75 | .Em bootverbose |
| 76 | flag |
| 77 | .Pq Ql \-v |
| 78 | might help in diagnosing the reason. Since the RTL 8002 requires |
| 79 | the availability of a working interrupt for the printer adapter (unlike |
| 80 | the |
| 81 | .Xr ppc 4 |
| 82 | driver), the |
| 83 | .Nm |
| 84 | driver fails to attach if the ethernet adapter cannot assert an |
| 85 | interrupt at probe time. |
| 86 | .Pp |
| 87 | The RTL 8002 doesn't support (hardware) multicast. |
| 88 | .Pp |
| 89 | The |
| 90 | .Nm |
| 91 | driver internally sets a flag so it gets probed very early. This way, |
| 92 | it is possible to configure both, an |
| 93 | .Nm |
| 94 | driver as well as a |
| 95 | .Xr ppc 4 |
| 96 | driver into the same kernel. If no RTL 8002 hardware is present, probing |
| 97 | will eventually detect the printer driver. |
| 98 | .Sh DIAGNOSTICS |
| 99 | .Dl "rdp0: configured IRQ (7) cannot be asserted by device" |
| 100 | .Pp |
| 101 | The probe routine was unable to get the RTL 8002 asserting an interrupt |
| 102 | request through the printer adapter. |
| 103 | .Pp |
| 104 | .Dl "rdp0: failed to find a valid hardware address in EEPROM" |
| 105 | .Pp |
| 106 | Since there doesn't seem to be a standard place for storing the hardware |
| 107 | ethernet address within the EEPROM, the |
| 108 | .Nm |
| 109 | driver walks the entire (serial) EEPROM contents until it finds something |
| 110 | that looks like a valid ethernet hardware address, based on the IEEE's |
| 111 | OUI assignments. This diagnostic tells the driver was unable to find |
| 112 | one. Note: it might as well be the current adapter is one of the rare |
| 113 | examples with a 74S288 EEPROM, so |
| 114 | .Ql flags 0x1 |
| 115 | should be tried. |
| 116 | .Pp |
| 117 | .Dl "rdp0: Device timeout" |
| 118 | .Pp |
| 119 | After initiating a packet transmission, the ethernet adapter didn't |
| 120 | return a notification of the (successful or failed) transmission. The |
| 121 | hardware is likely to be wedged, and is being reset. |
| 122 | .Sh SEE ALSO |
| 123 | .Xr ng_ether 4 , |
| 124 | .Xr ppc 4 , |
| 125 | .Xr ifconfig 8 |
| 126 | .Sh AUTHORS |
| 127 | This driver was written by |
| 128 | .An J\(:org Wunsch , |
| 129 | based on RealTek's packet driver for the RTL 8002, as well as on some |
| 130 | description of the successor chip, RTL 8012, gracefully provided by |
| 131 | RealTek. |
| 132 | .Sh BUGS |
| 133 | There are certainly many of them. |
| 134 | .Pp |
| 135 | Since the |
| 136 | .Nm |
| 137 | driver wants to probe its hardware at boot-time, the adapter needs |
| 138 | to be present then in order to be detected. |
| 139 | .Pp |
| 140 | Only two out of the eight different speed modes RealTek's packet |
| 141 | driver could handle are implemented. Thus there might be hardware |
| 142 | where even the current slow mode is too fast. |
| 143 | .Pp |
| 144 | There should be a DMA transfer test in the probe routine that figures |
| 145 | out the usable mode automatically. |
| 146 | .Pp |
| 147 | Abusing a standard printer interface for data exchange is error-prone. |
| 148 | Occasional stuck hardware shouldn't surprise too much, hopefully the |
| 149 | timeout routine will catch these cases. Flood-pinging is a good |
| 150 | example of triggering this problem. Likewise, albeit BPF is of course |
| 151 | supported, it's certainly a bad idea attempting to watch a crowded |
| 152 | ethernet wire using promiscuous mode. |
| 153 | .Pp |
| 154 | Since the RTL 8002 has only 4 KB of Rx buffer space (2 x 2 KB are used |
| 155 | as Tx buffers), the usual NFS deadlock with large packets arriving too |
| 156 | quickly could happen if a machine using the |
| 157 | .Nm |
| 158 | driver NFS-mounts some fast server with the standard NFS blocksize of |
| 159 | 8 KB. (Since NFS can only retransmit entire NFS packets, the same |
| 160 | packet will be retransmitted over and over again.) |
| 161 | .Pp |
| 162 | The heuristic to find out the ethernet hardware address from the |
| 163 | EEPROM sucks, but seems to be the only sensible generic way that |
| 164 | doesn't depend on the actual location in EEPROM. RealTek's sample |
| 165 | driver placed it directly at address 0, other vendors picked something |
| 166 | like 15, with other junk in front of it that must not be confused with |
| 167 | a valid ethernet address. |
| 168 | .Pp |
| 169 | The driver should support the successor chip RTL 8012, which seems to |
| 170 | be available and used these days. (The RTL 8002 is already somewhat |
| 171 | aged, around 1992/93.) The RTL 8012 offers support for advanced |
| 172 | printer adapter hardware, like bidirectional SPP, or EPP, which could |
| 173 | speed up the transfers substantially. The RTL 8012 also supports |
| 174 | hardware multicast, and has the ability to address 64 K x 4 packet |
| 175 | buffer RAM. |
| 176 | .Pp |
| 177 | The driver should be layered upon the ppc driver, instead of working |
| 178 | standalone, and should be available as a loadable module, so the |
| 179 | device probing can be deferred until the pocket ethernet adapter has |
| 180 | actually been attached. |