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Path: bloom-beacon.mit.edu!hookup!swrinde!emory!news-feed-2.peachnet.edu!concert!bigblue.oit.unc.edu!sunSITE!mdw From: Paul Gortmaker <gpg109@rsphysse.anu.edu.au> Newsgroups: comp.os.linux.announce,comp.os.linux.admin,comp.answers,news.answers Subject: Linux Ethernet HOWTO (Part 2/2) Followup-To: poster Date: 16 Mar 1994 05:27:09 GMT Organization: The University of North Carolina at Chapel Hill Lines: 1178 Approved: linux-announce@tc.cornell.edu (Matt Welsh) Message-ID: <2m65bd$e14@bigblue.oit.unc.edu> NNTP-Posting-Host: calzone.oit.unc.edu Keywords: Linux, Ethernet, TCP/IP, NET-2, network Originator: mdw@sunSITE Xref: bloom-beacon.mit.edu comp.os.linux.announce:1952 comp.os.linux.admin:5613 comp.answers:4182 news.answers:16451 Archive-Name: linux/howto/ethernet/part2 Last-Modified: 16 Mar 1994 [This is part 2/2 of the Ethernet-HOWTO.] 5 Technical information. For those who want to play with the present drivers, or try to make up their own driver for a card that is presently unsupported, this information should be useful. If you do not fall into this category, then perhaps you will want to skip this section. 5.01 Probed addresses While trying to determine what ethernet card is there, the following addresses are autoprobed, assuming the type and specs of the card have not been set in the kernel. As of 0.99pl12, doing a "make config" will ask what cards are to be supported. The file names below are in /usr/src/linux/drivers/net/ ---------------------------------------------------------------- wd.c: 0x300, 0x280, 0x380, 0x240 3c501.c 0x280 3c503.c: 0x300, 0x310, 0x330, 0x350, 0x250, 0x280, 0x2a0, 0x2e0 3c507.c: 0x300, 0x320, 0x340, 0x280 3c509.c: <Special "ID Port" probe> at1700.c: 0x300, 0x280, 0x380, 0x320, 0x340, 0x260, 0x2a0, 0x240 atp.c: 0x378, 0x278, 0x3bc depca.c 0x300, 0x200 d_link.c: 0x378 ne.c: 0x300, 0x280, 0x320, 0x340, 0x360 hp.c: 0x300, 0x320, 0x340, 0x280, 0x2C0, 0x200, 0x240 lance.c: 0x300, 0x320, 0x340, 0x360 smc-ultra.c: 0x200, 0x220, 0x240, 0x280, 0x300, 0x340, 0x380 eexpress.c: 0x300, 0x270, 0x320, 0x340 3c509.c: <Special "ID Port" probe> ---------------------------------------------------------------- There are some NE2000 clone ethercards out there that are waiting black holes for autoprobe drivers. While many NE2000 clones are safe until they are enabled, some can't be reset to a safe mode. These dangerous ethercards will hang any I/O access to their "dataports". The typical dangerous locations are: Ethercard jumpered base Dangerous locations (base + 0x10 - 0x1f) 0x300 * 0x310-0x317 0x320 0x330-0x337 0x340 0x350-0x357 0x360 0x370-0x377 * The 0x300 location is the traditional place to put an ethercard, but it's also a popular place to put other devices (often SCSI controllers). The 0x320 location is often the next one chosen, but that's bad for for the AHA1542 driver probe. The 0x360 location is bad, because it conflicts with the parallel port at 0x378. To avoid these lurking ethercard, here are the things you can do: o Probe for the device's BIOS in memory space. This is easy and always safe, but it only works for cards that always have BIOSes, like primary SCSI controllers. o Avoid probing any of the above locations until you think you've located your device. The NE2000 clones have a reset range from <base>+0x18 to <base>+0x1f that will read as 0xff, so probe there first if possible. It's also safe to probe in the 8390 space at <base>+0x00 - <base>+0x0f, but that area will return quasi-random values o If you must probe in the dangerous range, for instance if your target device has only a few port locations, first check that there isn't an NE2000 there. You can see how to do this by looking at the probe code in /usr/src/linux/net/inet/ne.c In other news, I've written the code for the I/O port registrar. Peter MacDonald and I have been intensely discussing this, and I think our current scheme has the necessary functionality with minimal kernel size impact. (The implementation involved rewriting the bitmap ops in kernel/ioport.c:ioperm() so that most code could be shared.) Here is the current "blurb". As usual comments are welcome. Please keep them substantial and constructive (we've already talked about changing the name from "reserve=" to "noprobe="). ================== Boot-Time Parameters: "reserve=" In some machines it may be necessary to prevent device drivers from checking for devices (auto-probing) in a specific region. This may be because of poorly designed hardware that causes the boot to "freeze" (such as some ethercards), hardware that is mistakenly identified, hardware whose state is changed by an earlier probe, or merely hardware you don't want the kernel to initialize. The "reserve" boot-time argument addresses this problem by specifying an I/O port region that shouldn't be probed. That region is reserved in the kernel's port registration table as if a device has already been found in that region. Note that this mechanism shouldn't be necessary on most machine, only when there is a problem or special case. The boot-line syntax is lilo-prompt: linux-image reserve=[<port>,<size>,<port>,<size>...] As usual with boot-time specifiers there is an 11 parameter limit, thus you can only specify 5 reserved regions per "reserve" keyword. Multiple "reserve" specifiers will work if you have an usually complicated request. If you specify a "reserve" region to protect a specific device, you must generally specify an explicit probe for that device. Most drivers ignore the port registration table if they are given an explicit address. 5.02 Skeleton / prototype driver OK. So you have decided that you want to write a driver for the Foobar Ethernet card, as you have the programming information, and it hasn't been done yet. (...these are the two main require- ments ;-) You can use the skeleton network driver that is provided with the Linux kernel source tree. It can be found in the file /usr/src/linux/drivers/net/skeleton.c as of 0.99pl15, and later. It's also very useful to look at the Crynwr (nee Clarkson) driver for your target ethercard, if it's available. Russ Nelson <nelson@crynwr.com> has been actively updating and writing these, and he has been very helpful with his code reviews of the current Linux drivers. 5.03 Driver interface to the kernel Here are some notes that may help when trying to figure out what the code in the driver segments is doing, or perhaps what it is supposed to be doing. ===================================================== int ethif_init(struct device *dev) { ... dev->send_packet = &ei_send_packet; dev->open = &ei_open; dev->stop = &ei_close; dev->hard_start_xmit = &ei_start_xmit; ... } int ethif_init(struct device *dev) This function is put into the device structure in Space.c. It is called only at boot time, and returns '0' iff the ethercard 'dev' exists. ===================================================== static int ei_open(struct device *dev) static int ei_close(struct device *dev) This routine opens and initializes the board in response to an socket ioctl() usually called by 'config' or 'ifconfig'. It is commonly stuffed into the 'struct device' by ethif_init(). The inverse routine is ei_close(), which should shut down the ethercard, free the IRQs and DMA channels if the hardware permits, and turn off anything that will save power (like the transceiver). (Note: As of NET-2, the relevant program is '/etc/ifconfig' - and the device *can* be turned off or on via passing 'up' or 'down' to 'ifconfig' from the command line with the device name.) ===================================================== static int ei_start_xmit(struct sk_buff *skb, struct device *dev) dev->hard_start_xmit = &ei_start_xmit; This routine puts packets to be transmitted into the hardware. It is usually stuffed into the 'struct device' by ethif_init(). When the hardware can't accept additional packets it should set the dev->tbusy flag. When additional room is available, usually during a transmit-complete interrupt, dev->tbusy should be cleared and the higher levels informed with mark_bh(INET_BH). [[Note: pre0.99.4 kernels didn't use this interface for all packets.]] ===================================================== ... if (dev_rint(buffer, length, is_skb ? IN_SKBUFF : 0, dev)) stats->rx_dropped++; ... A received packet is passed to the higher levels using dev_rint(). If the unadorned packet data in a memory buffer, dev_rint will copy it into a 'skbuff' for you. Otherwise a new skbuff should be kmalloc()ed, filled, and passed to dev_rint() with the IN_SKBUFF flag. ===================================================== 5.04 Interrupts and Linux There are two kinds of interrupt handlers in Linux: fast ones and slow ones. You decide what kind you are installing by the flags you pass to irqaction(). The fast ones, such as the serial interrupt handler, run with _all_ interrupts disabled. The normal interrupt handlers, such as the one for ethercard drivers, runs with other interrupts enabled. There is a two-level interrupt structure. The "fast" part handles the device register, removes the packets, and perhaps sets a flag. After it is done, and interrupts are re-enabled, the slow part is run if the flag is set. The flag between the two parts is set by: mark_bh(INET_BH); Usually this flag is set within dev_rint() during a received-packet interrupt, and set directly by the device driver during a transmit-complete interrupt. You might wonder why all interrupt handlers cannot run in "normal mode" with other interrupts enabled. Ross Biro uses this scenario to illustrate the problem: o You get a serial interrupt, and start processing it. The serial interrupt is now masked. o You get a network interrupt, and you start transferring a maximum-sized 1500 byte packet from the card. o Another character comes in, but this time the interrupts are masked! The "fast" interrupt structure solves this problem by allowing bounded-time interrupt handlers to run without the risk of leaving their interrupt lines masked by another interrupt request. There is an additional distinction between fast and slow interrupt handlers -- the arguments passed to the handler. A "slow" handler is defined as static void handle_interrupt(int reg_ptr) { int irq = -(((struct pt_regs *)reg_ptr)->orig_eax+2); struct device *dev = irq2dev_map[irq]; ... While a fast handler gets the interrupt number directly static void handle_fast_interrupt(int irq) { ... A final aspect of network performance is latency. The only board that really addresses this is the 3c509, which allows a predictive interrupt to be posted. It provides an interrupt response timer so that the driver can fine-tune how early an interrupt is generated. Alan Cox has some advice for anyone wanting to write drivers that are to be used with pl14 kernels and newer. He says: "Any driver intended for pl14 should use the new alloc_skb() and kfree_skbmem() functions rather than using kmalloc() to obtain an sk_buff. The new pl14 skeleton does this correctly. For drivers wishing to remain compatible with both sets the define 'HAVE_ALLOC_SKB' indicates these functions must be used. In essence replace skb=(struct sk_buff *)kmalloc(size) with skb=alloc_skb(size) and kfree_s(skb,size) with kfree_skbmem(skb,size) /* Only sk_buff memory though */ Any questions should I guess be directed to me since I made the change. This is a change to allow tracking of sk_buff's and sanity checks on buffers and stack behaviour. If a driver produces the message 'File: ??? Line: ??? passed a non skb!' then it is probable the driver is not using the new sk_buff allocators." 5.05 Programmed I/O vs. shared mem. vs. slave/master DMA Ethernet is 10Mbs. (Don't be pedantic, 3Mbs and 100Mbs don't count.) If you can already send and receive back-to-back packets, you just can't put more bits over the wire. Every modern ethercard can receive back-to-back packets. The Linux DP8390 drivers come pretty close to sending back-to-back packets (depending on the current interrupt latency) and the 3c509 and AT1500 hardware has no problem at all automatically sending back-to-back packets. The ISA bus can do 5.3MB/sec (42Mb/sec), which sounds like more than enough. You can use that bandwidth in several ways: Programmed I/O ============== Pro: Doesn't use any constrained system resources, just a few I/O registers, and has no 16M limit. Con: Usually the slowest transfer rate, the CPU is waiting the whole time, and interleaved packet access is usually difficult to impossible. Shared memory ============= Pro: Simple, faster than programmed I/O, and allows random access to packets. Con: Uses up memory space (a big one for DOS users, only a minor issue under Linux), and it still ties up the CPU. Slave (normal) DMA ================== Pro: Frees up the CPU during the actual data transfer. Con: Checking boundary conditions, allocating contiguous buffers, and programming the DMA registers makes it the slowest of all techniques. It also uses up a scarce DMA channel, and requires aligned low memory buffers. Master (bus-master) DMA ======================= Pro: Frees up the CPU during the data transfer, can string together buffers, can require little or no CPU time lost on the ISA bus. Con: Requires low-memory buffers and a DMA channel. Any bus-master will have problems with other bus-masters that are bus-hogs, such as some primitive SCSI adaptors. A few badly-designed motherboard chipsets have problems with bus-masters. And a reason for not using *any* type of DMA device is using a Cyrix 486 processor designed for plug-in replacement of a 386: these processors must flush their cache with each DMA cycle. 5.06 Programming the Intel chips (i82586 and i82593) These chips are used on a number of cards, namely the 3c507 ('86), the Intel EtherExpress 16 ('86), Microdyne's exos205t ('86), the Z-Note ('93), and the Racal-Interlan ni5210 ('86). Russ Nelson writes: "Most boards based on the 82586 can reuse quite a bit of their code. More, in fact, than the 8390-based adapters. There are only three differences between them: o The code to get the Ethernet address, o The code to trigger CA on the 82586, and o The code to reset the 82586. The Intel EtherExpress 16 is an exception, as it I/O maps the 82586. Yes, I/O maps it. Fairly clunky, but it works. Garrett Wollman did an AT&T driver for BSD that uses the BSD copyright. The latest version I have (Sep '92) only uses a single transmit buffer. You can and should do better than this if you've got the memory. The AT&T and 3c507 adapters do; the ni5210 doesn't. The people at Intel gave me a very big clue on how you queue up multiple transmit packets. You set up a list of NOP->XMIT->NOP->XMIT->NOP->XMIT->(beginning) blocks, then you set the "next" pointer of all the NOP blocks to themselves. Now you start the command unit on this chain. It continually processes the first NOP block. To transmit a packet, you stuff it into the next transmit block, then point the NOP to it. To transmit the next packet, you stuff the next transmit block and point the previous NOP to *it*. In this way, you don't have to wait for the previous transmit to finish, you can queue up multiple packets without any ambiguity as to whether it got accepted, and you can avoid the command unit start-up delay." 5.07 Technical information from 3Com From: Cameron Spitzer 764-6339 <camerons@nad.3com.com> Subject: getting 3Com Adapter manuals Date: Mon, 27 Sep 1993 21:17:07 +0200 Since this is becoming a FAQ, I'm going to tread the thin ice of No Commercial Use and answer it here. 3Com's Ethernet Adapters are documented for driver writers in our "Technical References" (TRs). These manuals describe the programmer interfaces to the boards but they don't talk about the diagnostics, installation programs, etc that end users can see. The Network Adapter Division marketing department has the TRs to give away. To keep this program efficient, we centralized it in a thing called "CardFacts." CardFacts is an automated phone system. You call it with a touch-tone phone and it faxes you stuff. To get a TR, call CardFacts at 408-727-7021. Ask it for Developer's Order Form, document number 9070. Have your fax number ready when you call. Fill out the order form and fax it to 408-764-5004. Manuals are shipped by Federal Express 2nd Day Service. If you don't have a fax and nobody you know has a fax, really and truly, *then* send mail to Terry_Murphy@3Mail.3Com.com and tell her about your problem. PLEASE use the fax thing if you possibly can. After you get a manual, if you still can't figure out how to program the board, try our "CardBoard" BBS at 1-800-876-3266, and if you can't do that, write Andy_Chan@3Mail.3com.com and ask him for alternatives. If you have a real stumper that nobody has figured out yet, the fellow who needs to know about it is Steve_Lebus@3Mail.3com.com. There are people here who think we are too free with the manuals, and they are looking for evidence that the system is too expensive, or takes too much time and effort. That's why it's important to try to use CardFacts *before* you start calling and mailing the people I named here. There are even people who think we should be like Diamond and Xircom, requiring tight "partnership" with driver writers to prevent poorly performing drivers from getting written. So far, 3Com customers have been really good about this, and there's no problem with the level of requests we've been getting. We need your continued cooperation and restraint to keep it that way. Cameron Spitzer, 408-764-6339 3Com NAD Santa Clara work: camerons@nad.3com.com home: cls@truffula.sj.ca.us 5.08 Notes on AMD PCnet-ISA / LANCE Based cards (79C960) The AMD LANCE (Local Area Network Controller for Ethernet) was the original offering, and has since been replaced by the "PCnet-ISA" chip, otherwise known as the 79C960. A relatively new chip from AMD, the 79C960, is the heart of many new cards being released at present. Note that the name "LANCE" has stuck, and some people will refer to the new chip by the old name. Dave Roberts of the Network Products Division of AMD was kind enough to contribute the following information regarding this chip: "As for the architecture itself, AMD developed it originally and reduced it to a single chip -- the PCnet(tm)-ISA -- over a year ago. It's been selling like hotcakes ever since. Functionally, it is equivalent to a NE1500. The register set is identical to the old LANCE with the 1500/2100 architecture additions. Older 1500/2100 drivers will work on the PCnet-ISA. The NE1500 and NE2100 architecture is basically the same. Initially Novell called it the 2100, but then tried to distinguish between coax and 10BASE-T cards. Anything that was 10BASE-T only was to be numbered in the 1500 range. That's the only difference. Many companies offer PCnet-ISA based products, including HP, Racal-Datacom, Allied Telesis, Boca Research, Kingston Technology, etc. The cards are basically the same except that some manufacturers have added "jumperless" features that allow the card to be configured in software. Most have not. AMD offers a standard design package for a card that uses the PCnet-ISA and many manufacturers use our design without change. What this means is that anybody who wants to write drivers for most PCnet-ISA based cards can just get the data-sheet from AMD. Call our literature distribution center at (800)222-9323 and ask for the Am79C960, PCnet-ISA data sheet. It's free. A quick way to understand whether the card is a "stock" card is to just look at it. If it's stock, it should just have one large chip on it, a crystal, a small IEEE address PROM, possibly a socket for a boot ROM, and a connector (1, 2, or 3, depending on the media options offered). Note that if it's a coax card, it will have some transceiver stuff built onto it as well, but that should be near the connector and away from the PCnet-ISA. The PCnet-ISA is faster than the original LANCE design and makes better use of the available bus bandwidth. Additionally, some LANCE bugs were corrected and many enhancements were made." There is also some info regarding the LANCE chip in the file lance.c which is included in the standard kernel. 5.09 Multicast and Promiscuous mode One of the things I've been working on recently is the major remaining item on the ethercard feature list: implementing multicast and promiscuous mode hooks. At first I was planning to do it while implementing either the /dev/* or DDI interface, but that's not really the correct way to do it. We should only enable multicast or promiscuous modes when something wants to look at the packets, and shut it down when that application is finished, neither of which is strongly related to when the hardware is opened or released. I'll start by discussing promiscuous mode, which is conceptually easy to implement. For most hardware you only have to set a register bit, and from then on you get every packet on the wire. Well, it's almost that easy; for some hardware you have to shut the board (potentially dropping a few packet), reconfigure it, and then re-enable the ethercard. This is grungy and risky, but the alternative seems to be to have every application register before you open the ethercard at boot-time. OK, so that's easy, so I'll move on something that's not quite so obvious: Multicast. It can be done two ways: 1) Use promiscuous mode, and a packet filter like the Berkeley packet filter (BPF). The BPF is a pattern matching stack language, where you write a program that picks out the addresses you are interested in. Its advantage is that it's very general and programmable. Its disadvantage is that there is no general way for the kernel to avoid turning on promiscuous mode and running every packet on the wire through every registered packet filter. See the next section for more information on BPF. 2) Using the built-in multicast filter that most etherchips have. I guess I should list what a few ethercards/chips provide: Chip/card Promiscuous Multicast filter ======================================== Seeq8001/3c501 Yes Binary filter (1) 3Com/3c509 Yes Binary filter (1) 8390 Yes Autodin II six bit hash (2) (3) LANCE Yes Autodin II six bit hash (2) (3) i82586 Yes Hidden Autodin II six bit hash (2) (4) (1) These cards claim to have a filter, but it's a simple yes/no 'accept all multicast packets', or 'accept no multicast packets'. (2) AUTODIN II is the standard ethernet CRC (checksum) polynomial. In this scheme multicast addresses are hashed and looked up in a hash table. If the corresponding bit is enabled, this packet is accepted. Ethernet packets are laid out so that the hardware to do this is trivial -- you just latch six (usually) bits from the CRC circuit (needed anyway for error checking) after the first six octets (the destination address), and use them as an index into the hash table (six bits == a 64-bit table). (3) These chips use the six bit hash, and must have the table computed and loaded by the host. This means the kernel must include the CRC code. (4) The 82586 uses the six bit hash internally, but it computes the hash table itself from a list of multicast addresses to accept. Note that none of these chips do perfect filtering, and we still need a middle-level module to do the final filtering. Also note that in every case we must keep a complete list of accepted multicast addresses to recompute the hash table when it changes. My first pass at device-level support is detailed in the new outline driver skeleton.c (pl14 and up.) It looks like the following: #ifdef HAVE_MULTICAST static void set_multicast_list(struct device *dev, int num_addrs, void *addrs); #endif . . ethercard_open() { ... #ifdef HAVE_MULTICAST dev->set_multicast_list = &set_multicast_list; #endif ... #ifdef HAVE_MULTICAST /* Set or clear the multicast filter for this adaptor. num_addrs == -1 Promiscuous mode, receive all packets num_addrs == 0 Normal mode, clear multicast list num_addrs > 0 Multicast mode, receive normal and MC packets, and do best-effort filtering. */ static void set_multicast_list(struct device *dev, int num_addrs, void *addrs) { ... Any comments, criticism, etc. are welcome. Alan Cox adds that "...in pl14, user programs can access promiscuous mode but not multicast mode, even though the drivers support both. The ifconfig program allows you to mark an interface 'promisc'." 5.10 The Berkeley Packet Filter (BPF) I'm not bitterly opposed to it, but I'm coming to the conclusion that the 'bpf' functionality should not be provided by the kernel, but should be in a (hopefully little-used) compatibility library. For those not in the know: 'bpf' (the Berkeley Packet Filter) is an mechanism for specifying to the kernel networking layers what packets you are interested in. It's implemented as a specialized stack language interpreter built into a low level of the networking code. An application passes a program written in this language to the kernel, and the kernel runs the program on each incoming packet. If the kernel has multiple 'bpf' applications, each program is run on each packet. The problem is that it's difficult to deduce what kind of packets the application is really interested in from the packet filter program, so the general solution is to always run the filter. Imagine a program that registers a 'bpf' program to pick up a low data-rate stream sent to a multicast address. Most ethernet cards have a hardware multicast address filter implemented as a 64 entry hash table that ignores most unwanted multicast packets, so the capability exists to make this a very inexpensive operation. But with the BFP the kernel must switch the interface to promiscuous mode, receive _all_ packets, and run them through this filter. This is work, BTW, that's very difficult to account back to the process requesting the packets. 5.11 Unresolved questions / concerns There may be some benefit from processing packet data as it is transferred to and from the ethercard, especially with very fast processors transferring data to a slow ethercard. As I see it this question has multiple parts: 1) Is there any useful processing power available, perhaps during the ISA bus recovery period, or while the 8390 remote DMA is preparing for another transfer?? 2) Is there any useful but simple work that can be done between/during each word of the copy, such as calculating a CRC, or discarding obviously unwanted packets?? 3) would the complexity of an interface to do this make future ethercard drivers impossible?? There should be a better structure than Space.c - Drivers should be able to autoprobe for all installed ethercards rather than just quitting after finding the first. I've written code to do this, but the constant promise (threat?) of DDI has prevented me from making it standard. A related topic is the problem of driver probes corrupting unrelated hardware. Even worse is a probe into a dataport that isn't set up to transfer data, which will freeze the machine. The common suggestion is a boot-time device registry that records already-used I/O ports and shared memory. This has been implemented as of pl13, see section 5.01. 6 Possible problems, and troubleshooting. This section tries to answer any unresolved questions, and not so common solutions to common problems. They are sorted on a "per manufacturer basis". You should have also read the relevant info. from section 1 about your specific card. Section 8 contains more general FAQ's. 6.01 Problems with NE2000 (and clones) "DMA address mismatch" ====================== Is the chip a real NatSemi 8390? (DP8390, DP83901, DP83902 or DP83905)? If not, some clone chips don't correctly implement the transfer verification register. MS-DOS drivers never do error checking, so it doesn't matter to them. Are most of the messages off by a factor of 2? If so: Are you using the NE2000 in a 16 bit slot? Is it jumpered to use only 8 bit transfers? The Linux driver expects a NE2000 to be a 16 bit slot. A NE1000 can be in either size slot. This problem can also occur with some clones, notably D-Link 16 bit cards, that don't have the correct ID bytes in the station address PROM. [[ This should be fixed in pl12.]] Are you running the bus faster than 8Mhz? If you can change the speed (faster or slower), see if that makes a difference. Most NE2000 clones will run at 16Mhz, but some may not. Changing speed can also mask a noisy bus. What other devices are on the bus? If moving the devices around changes the reliability, then you have a bus noise problem -- just what that error message was designed to detect. Congratulations, you've probably found the source of other problems as well. Machine Hangs during Boot. ========================== Problem: The machine hangs during boot right after the "8390..." or "WD...." message. Removing the NE2000 fixes the problem. Solution: Change your NE2000 base address to 0x360 (or 0x340 for pl12 or later kernels.) Alternatively, you can use the new device registrar implemented in pl13 (see section 5.1) Reason: Your NE2000 clone isn't a good enough clone. An active NE2000 is a bottomless pit that will trap any driver autoprobing in its space. The other ethercard drivers take great pain to reset the NE2000 so that it's safe, but some clones cannot be reset. Clone chips to watch out for: Winbond 83C901. Changing the NE2000 to a less-popular address will move it out of the way of other autoprobes, allowing your machine to boot. Problem: The machine hangs during the SCSI probe at boot. Solution: It's the same problem as above, change the ethercard's address, or use the device registrar. Problem: The machine hangs during the soundcard probe at boot. Solution: No, that's really during the silent SCSI probe, and it's the same problem as above. "eth0: DMAing conflict in ne_block_input" ========================================= This bug came from timer-based packet retransmissions. If you got a timer tick _during_ a ethercard RX interrupt, and timer tick tried to retransmit a timed-out packet, you could get a conflict. Because of the design of the NE2000 you would have the machine hang (exactly the same the NE2000-clone boot hangs). Early versions of the driver disabled interrupts for a long time, and didn't have this problem. Later versions are fixed. (ie. kernels after 0.99p9 should be OK.) NE2000 not detected at boot. ============================ A few people have reported a problem with detecting the Accton NE2000. This problem occurs only at boot-time, and the card is later detected at run-time by the identical code my (alpha-test) ne2k diagnostic program. Accton has been very responsive, but I still haven't tracked down what is going on. I've been unable to reproduce this problem with the Accton cards we purchased. If you are having this problem, please send me an immediate bug report. For that matter, if you have an Accton card send me a success report, including the type of the motherboard. I'm especially interested in finding out if this problem moves with the particular ethercard, or stays with the motherboard. Here are some things to try, as they have fixed it for some people: 1) Change the bus speed, or just move the card to a different slot (!). 2) Change the "I/O recovery time" parameter in the BIOS chipset configuration. 3) Make the following code change suggested by David Cutler, <dave@dmitri.ucdavis.edu> to ne.c around line 150: for(i = 0; i < 32 /*sizeof(SA_prom)*/; i+=2) { - SA_prom[i] = inb_p(ioaddr + NE_DATAPORT); - SA_prom[i+1] = inb_p(ioaddr + NE_DATAPORT); + SA_prom[i] = inb(ioaddr + NE_DATAPORT); + SA_prom[i+1] = inb(ioaddr + NE_DATAPORT); if (SA_prom[i] != SA_prom[i+1]) wordlength = 1; } Yes, this removes the delay between board accesses, something that would normally increase the likelihood of data corruption rather than decreasing it. Note that this change is already incorporated into pl15. If you have an older kernel, you may have to do it yourself. 6.02 Problems with WD80*3 cards Detected Non-existent Ethercard =============================== Problem: A WD80*3 is falsely detected. Removing the sound or MIDI card eliminates the "detected" message. Solution: Update your ethercard driver: new versions include an additional sanity check. Reason: Some MIDI ports happen to produce the same checksum as a WD ethercard. Error messages from the 80*3 ============================ Problem: You get messages such as the following with your 80*3: eth0: bogus packet size, status = ........ kmalloc called with impossibly large argument (65400) eth0: Couldn't allocate sk_buff of size 65400 eth0: receiver overrun Reason: There is a shared memory problem. Solution: If the problem is sporadic, you have hardware problems. Typical problems that are easy to fix are board conflicts, having cache or "shadow ROM" enabled for that region, or running your bus faster than 8Mhz. There are also a surprising number of memory failures on ethernet cards, so run a diagnostic program if you have one for your ethercard. If the problem is continual, and you have have to reboot to fix the problem, record the boot-time probe message and mail it to becker@super.org - Take particular note of the shared memory location. Will not detect my 80x3 ======================= Reason: The Mitsumi CD-ROM (mcd) driver probe at 0x300 will succeed if just about *anything* is that I/O location. This is bad news and needs to be a bit more robust. (pl15) Once another driver registers that it "owns" an I/O location, other drivers (incl. the wd80x3) are "locked out" and can not probe that addr for a card. Solution: Recompile a new kernel without any excess drivers that you aren't using, including the above mcd driver. Or try moving your ethercard to a new I/O addr. Valid I/O addr. for all the cards are listed in section 5.1 You can also point the mcd driver off in another direction by a boot-time parameter (via LILO) such as: "mcd=0x200,12" 6.03 Problems with 3Com cards Choosing the Interrupt of the 3c503 =================================== Problem: The 3c503 picks IRQ n at boot, but this is needed for some other device which needs IRQ n. (eg. CD ROM driver, etc.) Can this be fixed without compiling this into the kernel? Solution: The 3c503 driver probes for a free IRQ line in the order {5, 9/2, 3, 4}, and it should pick a line which isn't being used. The pre-pl12 (SLS 1.02) driver picked the IRQ line at boot-time, and the current driver (pl12) chooses when the card is open()/'ifconfig'ed. Note the "bug" noted in the 3c503 section in 1.01 Alternately, you can fix the IRQ at boot by passing parameters via LILO. The following selects IRQ9, base location 0x300, <ignored value>, and if_port #1 (the external transceiver). lilo: linux ether=9,0x300,0,1,eth0 The following selects IRQ3, probes for the base location, <ignored value>, and the default if_port #0 (the internal transceiver) lilo: linux ether=3,0,0,0,eth0 "3c503: Configured interrupt number XX is out of range." ======================================================== Problem: Whoever built your kernel fixed the ethercard IRQ at XX. Reason: The above is truly evil, and worse than that, it is not necessary. The 3c503 will autoIRQ when it gets "ifconfig"ed, and pick one of IRQ{5, 2/9, 3, 4}. Solution: Use lilo to set the IRQ, or rebuild the kernel, enabling autoIRQ by not specifying the IRQ line. Choosing the output of the 3c503 ================================ Problem: The supplied 3c503 drivers don't use the AUI (thicknet) port. How does one choose it over the default thinnet port? Solution: The 3c503 AUI port can be selected at boot-time with 0.99pl12 and later. The selection is overloaded onto the low bit of the currently-unused dev->rmem_start variable, so a boot-time parameter of: lilo: linux ether=0,0,0,1,eth0 should work. A boot line to force IRQ 5, port base 0x300, and use an external transceiver is: lilo: linux ether=5,0x300,0,1,eth0 7 Networking with a laptop computer There are currently only a few ways to put your laptop on a network. You can use the SLIP code (and run at serial line speeds); you can buy one of the few laptops that come with a NE2000-compatible ethercard or PCMCIA slot built-in; you can get a laptop with a docking station and plug in an ISA ethercard; or you can use a parallel port Ethernet adapter such as the D-Link DE-600. 7.01 Option 1 -- using SLIP This is the cheapest solution, but by far the most difficult. Also, you will not get very high transmission rates. Since SLIP is not really related to ethernet cards, it will not be discussed further here. See the NET-2 HOWTO. 7.02 Option 2 -- Built in NE2000 compatible or PCMCIA Ethercard. The second solution severely limits your laptop choices and is fairly expensive. Be sure to read the specifications carefully, you may find that you will have to buy an additional non-standard transceiver to actually put the machine on a network. As this area of Linux development is fairly young, I'd suggest that you join the LAPTOPS mailing channel. See section 0.02 which describes how to join a mailing list channel. Try and determine exactly what hardware you have (ie. card manufacturer, PCMCIA chip controller manufacturer) and then ask on the LAPTOPS channel. Regardless, don't expect things to be all that simple. Expect to have to fiddle around a bit, and patch kernels, etc. Maybe someday you will be able to type "make config" 8-) There is a number of programs on tsx-11.mit.edu in /pub/linux/packages/laptops/ that you may find useful. These range from PCMCIA Ethercard drivers to programs that communicate with the PCMCIA controller chip. Note that these drivers are usually tied to a specific PCMCIA chip (ie. the intel 82365 or the TCIC/2) On a brighter note, I know that people have used the Linksys/D-Link 650 PCMCIA Ethernet PC Card with both controller chipsets, so it *can* be done. I have also seen reports of people using the IBM Credit Card Adapter for Ethernet with the intel 82365 chip. This is all just from following the LAPTOPS channel. The 3c589 from 3Com is supposed to look a lot like a 3c509. Anyway, the PCMCIA driver problem isn't specific to the Linux world. It's been a real disaster in the MS-DOS world. In that world people expect the hardware to work if they just follow the manual. They might not expect it to interoperate with any other hardware or software, or operate optimally, but they do expect that the software shipped with the product will function. Many PCMCIA adaptors don't pass this test. 7.03 Option 3 -- ISA Ethercard in the Docking Station. I recommend the third solution. Docking stations for laptops typically cost about $250 and provide two full-size ISA slots, two serial and one parallel port. Most (all?) docking stations are powered off of the laptop's batteries, and a few allow adding extra batteries in the docking station if you use short ISA cards. You can add an inexpensive ethercard and enjoy full-speed ethernet performance. 7.04 Option 4 -- Pocket / parallel port adaptors. The "pocket" ethernet adaptors may also fit your need. Until recently they actually costed more than a docking station and cheap ethercard, and most tie you down with a wall-brick power supply. At present, you can choose from the D-Link, or the RealTek adaptor. Most other companies, especially Xircom, treat the programming information as a trade secret, so support will likely be slow in coming. You can sometimes avoid the wall-brick with the adaptors by buying or making a cable that draws power from the laptop's keyboard port. (This is mentioned in the info. for the AT-Lan-Tec unit.) The keyboard pinouts (5 pin DIN) are as follows: Signal/Function Pin # --------------- ----- KEYCLK (clock) 1 KEYDAT (data) 2 N/C 3 Ground 4 +5 V 5 A quick check with a voltmeter will verify which pins are 4 and 5 if you are not sure. 8 Frequently asked questions Here are some of the more frequently asked questions about using Linux with an Ethernet connection. Some of the more specific questions are sorted on a "per manufacturer basis" and are listed in the "Troubleshooting" section. (section 6). However, since this document is basically "old" by the time you get it, any "new" problems will not appear here instantly. For these, I suggest that you make efficient use of your newsreader. For example, nn users would type nn -xX -s'3c' to get all the news articles in your subscribed list that have "3c" in the subject. (ie. 3com, 3c509, 3c503, etc.) The moral: Read the man page for your newsreader. 8.01 Just the FAQ's ma'am -- just the FAQ's. Q: I heard that there is an alpha driver available for my card. Where can I get it? A: Assuming that it is a djb driver, it will be on ftp.super.org in the /pub/linux/ area. Things change here quite frequently, so just look around for it. There is usually only about 3 subdirs, so you should be able to find it. Now, if it really is an alpha, or pre-alpha driver, then please treat it as such. In other words, don't complain because you can't figure out what to do with it. If you can't figure out how to install it, then you probably shouldn't be testing it. Also, if it brings your machine down, don't complain. Instead, send us a well documented bug report, or even better, a patch! Q: Is there token ring support for Linux? A: No, there is no token ring support in Linux. To support token ring requires more than only a writing a device driver, it also requires writing the source routing routines for token ring. Given that token ring is expensive, not fast, and will probably be swept away by 100baseVG in a few months, it doesn't seem worth it to write a driver. In case anyone wants to, I looked at writing a token ring device driver, and concluded that the hardware interface wasn't too difficult to do, but writing the support for source routing would take significantly longer than I was willing to spend on an expensive and dying technology. Alan Cox adds: "It will require [...] changes to the bottom socket layer to support 802.2 and 802.2 based TCP/IP. Don't expect anything soon." Q: Is there FDDI support for Linux? A: No, there is no Linux driver for any FDDI boards. I come from a place with supercomputers, so an external observer might think FDDI would be high on my list. But FDDI never delivered end-to-end throughput that would justify its cost, and it seems to be a nearly abandoned technology now that 100base{X,Anynet} seems imminent. (And yes, I know you can now get FDDI boards for <$1K. That seems to be a last-ditch effort to get some return on the development investment. Where is the next generation of FDDI going to come from?) Q: Can I link 10BaseT (RJ45) based systems together without a hub? A: You can link 2 machines easily, but no more than that, without extra devices/gizmos. See section 4 on wiring -- it explains how to do it. And no, you can't hack together a hub just by crossing a few wires and stuff. It's pretty much impossible to do the collision signal right without duplicating a hub. Q: Is there IPX or Novell support available for Linux? A: Alan Cox writes: "The novell protocols are available from novell for various amounts. IPX is freely documented. SPX is about $1000 but I'm told Xerox SPP is identical. _PLEASE_ has anyone got any freely distributable Xerox SPP code/documentation? The novell server spec costs you $15000 + royalties providing you only want to write a client, or $30000 + royalties otherwise. Needless to say the final output has to be binary only and subject to a novell license. Reading their license rules by my interpretation its also impossible for us to do because you would seem to have to bar disassembly of your final result, which is not allowed in the EEC. Bits of NCP are known, and I hope eventually enough will be known to write limited NCP support into Linux, for the moment I'm poking around at IPX, tho this will have to wait until the new network code is finished. An Alpha test IPX protocol layer is available from me (Alan) for pl14 or higher. People are also exploring the issue of NCP and the new Dr Dobbs journal article on the innards of netware has provided a core of good information." As an alternative, Miquel van Smoorenburg suggests the following: "It _is_ possible to set up a dedicated PC running both novell and the PD SOSS server and let it gateway from NFS to novell. This way it is possible to mount the Novell drives on the Unix client. SOSS is a PD (perhaps with some restrictions, but freely available) NFS server for DOS. It includes the PC/IP TCP/IP implementation and runs on a packet driver. I have run both a Novell client (with PDIPX, a Packet Driver IPX) and this SOSS server together successfully." You can get "Stan's Own Server System" from the following location: hilbert.wharton.upenn.edu:pub/tcpip/soss.zip Note that this version has the IP bugs fixed and the subdirs with extensions bug fixed. Some of the soss.zoo archives do not contain these fixes. Q: What needs to be done so that Linux can run two ethernet cards? A: The easiest solution is to get 0.99pl13 or newer, as the hooks for multiple ethercards are all there. You can enable additional ethercards with LILO parameters such as: lilo: linux ether=5,0x300,0,1,eth0 ether=15,0x280,eth1 These boot time arguments can be made permanent so that you don't have to re-enter them every time. See the LILO manual. Q: Okay, I can run 2 cards -- can I run Linux as a gateway between two networks? A: This is really a question for the NET-HOWTO, but it is answered here anyways: Charles Hedrick (aka Mr. Slip) had this to say: "Yes, however I'm a bit nervous about doing it. The problem isn't functionality -- there's IP forwarding code, and as far as I know, it works. Some people do use it. However routers need to be particularly careful to avoid creating network problems such as "meltdowns." The Linux IP layer doesn't have quite enough of these protective features. It will only cause trouble if other hosts on your network are misconfigured, and even then it probably won't cause much trouble (assuming that only systems actually acting as gateways are built with IP_FORWARD enabled). But I'd still rather use a router that met all of the requirements of the host and router requirements in the RFC's. (Note that not all other Unix implementations do either. I'm concerned about things like not sending ICMP responses to messages that arrive as media broadcasts. 386BSD looks OK, but older BSD-based implementations often didn't do all of these checks.) It depends a lot on what the network is like and how critical it is. For a home setup with a couple of hosts, I see no problem at all. But I would not consider using Linux as a router on a large campus network at the moment. I still think that by release 1.0, Linux will be a reasonably well-behaved host. But I think use as a router in critical situations should wait until somebody has checked the ip and icmp modules for compliance with RFC 1009 and a few other specs." Q: I have /dev/eth0 as a link to /dev/xxx. Is this right? A: Contrary to what you have heard, the files in /dev/* are not used. I originally thought that they might be an OK idea. I've since concluded that they won't work, at least in the documented form. Q: Should I disable trailers when I "ifconfig" my ethercard? A: You can't disable trailers, and you shouldn't want to. 'Trailers' are a hack to avoid data copying in the networking layers. The idea was to use a trivial fixed-size header of size 'H', put the variable-size header info at the end of the packet, and allocate all packets 'H' bytes before the start of a page. While it was a good idea, it turned out to not work well in practice. If someone suggests the use of '-trailers', note that it is the equivalent of sacrificial goats blood. It won't do anything to solve the problem, but if problem fixes itself then someone can claim deep magical knowledge. 9 Miscellaneous. Any other associated stuff that didn't fit in anywhere else gets dumped here. It may not be relevant, and it may not be of general interest but it is here anyway. 9.01 Bad Vendors #define SOAPBOX There used to be some horror stories here about dealings with Cabletron and Xircom. They were pretty ugly and gruesome. Basically these companies are the ethernet equivalent of what Diamond is to XFree86. They do not want to release vital information on low-level programming of their hardware. For something like Linux, where the source code for everything is out in the open, this makes their hardware difficult or impossible to use. However, like Diamond, when confronted with the fact that they are losing sales from Linux/BSD users, they basically shrug it off, saying that it is only a small percentage of the total sales. If you can afford the time, drop these vendors a note (via e-mail or snail-mail) and tell them politely that the fact that they don't support open software systems such as Linux has forced you to exclude them from the vendors that you are purchasing hardware from. It may not make any immediate difference, but it might make you feel better. Besides, a few seconds of your time is a cheap price to pay for *all* that free Linux software you are using. 8-) #undef SOAPBOX 9.02 Closing If you have found any glaring typos, or outdated info in this document, please let one of us know. It's getting big, and it is easy to overlook stuff. Paul Gortmaker <gpg109@rsphy1.anu.edu.au> Donald J. Becker <becker@super.org> =========== end of Ethernet HOWTO ============