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authorLinus Torvalds <torvalds@linux-foundation.org>2026-09-05 11:59:05 -0700
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Merge tag 'driver-core-7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-coregrafted
Pull driver core fixes from Danilo Krummrich: - Fix kernfs listxattr() not returning security xattr names (e.g. SELinux labels) when the kernfs node has no allocated kernfs_iattrs - Fix silent truncation of IRQ vector indices in the Rust PCI abstractions - Don't select OF from DRIVER_PE_KUNIT_TEST; skip the test when OF is disabled instead of silently enabling extra kernel functionality - Russ Weight is retiring from kernel development; update the Firmware Loader sysfs contact to the driver-core mailing list, add a CREDITS entry for Firmware Upload, and update MAINTAINERS accordingly * tag 'driver-core-7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: MAINTAINERS: Remove Russ Weight from Firmware Loader CREDITS: Add CREDITS entry for Firmware Upload firmware_loader: Change contact for sysfs nodes rust: pci: reject IRQ vector indices that do not fit in u32 kernfs: preserve security xattrs without allocating iattrs drivers: base: test: DRIVER_PE_KUNIT_TEST should not select OF
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+.. SPDX-License-Identifier: GPL-2.0
+
+======
+ARCnet
+======
+
+:Author: Avery Pennarun <apenwarr@worldvisions.ca>
+
+.. note::
+
+ See also arcnet-hardware.rst in this directory for jumper-setting
+ and cabling information if you're like many of us and didn't happen to get a
+ manual with your ARCnet card.
+
+----
+
+These are the ARCnet drivers for Linux.
+
+This new release (2.91) has been put together by David Woodhouse
+<dwmw2@infradead.org>, in an attempt to tidy up the driver after adding support
+for yet another chipset. Now the generic support has been separated from the
+individual chipset drivers, and the source files aren't quite so packed with
+#ifdefs! I've changed this file a bit, but kept it in the first person from
+Avery, because I didn't want to completely rewrite it.
+
+The previous release resulted from many months of on-and-off effort from me
+(Avery Pennarun), many bug reports/fixes and suggestions from others, and in
+particular a lot of input and coding from Tomasz Motylewski. Starting with
+ARCnet 2.10 ALPHA, Tomasz's all-new-and-improved RFC1051 support has been
+included and seems to be working fine!
+
+
+.. _arcnet-netdev:
+
+Where do I discuss these drivers?
+---------------------------------
+
+ARCnet discussions take place on netdev. Simply send your email to
+netdev@vger.kernel.org and make sure to Cc: maintainer listed in
+"ARCNET NETWORK LAYER" heading of Documentation/process/maintainers.rst.
+
+Other Drivers and Info
+----------------------
+
+You can try JoAnne Schmitz's ARCNET page on the World Wide Web at:
+
+ https://www.qis.net/~jschmitz/arcnet/
+
+
+Supported Hardware
+------------------
+
+Only PCI and PCI Express devices based on the COM20020 chipset are supported.
+This is the newest chipset from SMC with support for promiscuous mode (packet
+sniffing), extra diagnostic information, etc. These devices use the com20020_pci
+driver.
+
+Support for older chipsets and ISA and PCMCIA devices was previously available
+but has been removed.
+
+
+Configuring the Driver
+----------------------
+
+The COM20020 driver will be loaded automatically at boot if a supported card is
+detected.
+
+If the com20020_pci driver was compiled as a loadable module, the options are::
+
+ node=<node_ID> backplane=<backplane> clockp=<CKP> clockm=<CKM>
+ timeout=<timeout> device=<interface_name>
+
+If the driver was compiled into the kernel, the same options can be specified on
+the kernel command line by prefixing them with `com20020_pci.`, as in the
+following example::
+
+ com20020_pci.device=eth1
+
+The COM20020 chipset allows you to set the node ID in software, overriding the
+default which is still set in DIP switches on the card. If you don't have the
+COM20020 data sheets, and you don't know what the other options refer
+to, then they won't interest you - forget them.
+
+Otherwise, ARCnet can be configured in a similar way to Ethernet, with the
+exception that ARCnet interface names begin with `arc`.
+
+
+How do I get it to work with...?
+--------------------------------
+
+NFS:
+ Should be fine linux->linux, just pretend you're using Ethernet cards.
+ oak.oakland.edu:/simtel/msdos/nfs has some nice DOS clients. There
+ is also a DOS-based NFS server called SOSS. It doesn't multitask
+ quite the way Linux does (actually, it doesn't multitask AT ALL) but
+ you never know what you might need.
+
+ With AmiTCP (and possibly others), you may need to set the following
+ options in your Amiga nfstab: MD 1024 MR 1024 MW 1024
+ (Thanks to Christian Gottschling <ferksy@indigo.tng.oche.de>
+ for this.)
+
+ Probably these refer to maximum NFS data/read/write block sizes. I
+ don't know why the defaults on the Amiga didn't work; write to me if
+ you know more.
+
+DOS:
+ If you're using the freeware arcether.com, you might want to install
+ the driver patch from my web page. It helps with PC/TCP, and also
+ can get arcether to load if it timed out too quickly during
+ initialization. In fact, if you use it on a 386+ you REALLY need
+ the patch, really.
+
+Windows:
+ See DOS :) Trumpet Winsock works fine with either the Novell or
+ Arcether client, assuming you remember to load winpkt of course.
+
+LAN Manager and Windows for Workgroups:
+ These programs use protocols that
+ are incompatible with the Internet standard. They try to pretend
+ the cards are Ethernet, and confuse everyone else on the network.
+
+ The Linux ARCnet driver supports this protocol via the 'arc0e' device.
+ See the section on "Multiprotocol Support" for more information.
+
+ Using the freeware Samba server and clients for Linux, you can now
+ interface quite nicely with TCP/IP-based WfWg or Lan Manager
+ networks.
+
+Windows 95:
+ Tools are included with Win95 that let you use either the LANMAN
+ style network drivers (NDIS) or Novell drivers (ODI) to handle your
+ ARCnet packets. If you use ODI, you'll need to use the 'arc0'
+ device with Linux. If you use NDIS, then try the 'arc0e' device.
+ See the "Multiprotocol Support" section below if you need arc0e,
+ you're completely insane, and/or you need to build some kind of
+ hybrid network that uses both encapsulation types.
+
+OS/2:
+ I've been told it works under Warp Connect with an ARCnet driver from
+ SMC. You need to use the 'arc0e' interface for this. If you get
+ the SMC driver to work with the TCP/IP stuff included in the
+ "normal" Warp Bonus Pack, let me know.
+
+ ftp.microsoft.com also has a freeware "Lan Manager for OS/2" client
+ which should use the same protocol as WfWg does. I had no luck
+ installing it under Warp, however. Please mail me with any results.
+
+NetBSD/AmiTCP:
+ These use an old version of the Internet standard ARCnet
+ protocol (RFC1051) which is compatible with the Linux driver v2.10
+ ALPHA and above using the arc0s device. (See "Multiprotocol ARCnet"
+ below.) ** Newer versions of NetBSD apparently support RFC1201.
+
+
+Using Multiprotocol ARCnet
+--------------------------
+
+The ARCnet driver supports three protocols, each on its own
+"virtual network device":
+
+ ====== ===============================================================
+ arc0 RFC1201 protocol, the official Internet standard which just
+ happens to be 100% compatible with Novell's TRXNET driver.
+ Version 1.00 of the ARCnet driver supported _only_ this
+ protocol. arc0 is the fastest of the three protocols (for
+ whatever reason), and allows larger packets to be used
+ because it supports RFC1201 "packet splitting" operations.
+ Unless you have a specific need to use a different protocol,
+ I strongly suggest that you stick with this one.
+
+ arc0e "Ethernet-Encapsulation" which sends packets over ARCnet
+ that are actually a lot like Ethernet packets, including the
+ 6-byte hardware addresses. This protocol is compatible with
+ Microsoft's NDIS ARCnet driver, like the one in WfWg and
+ LANMAN. Because the MTU of 493 is actually smaller than the
+ one "required" by TCP/IP (576), there is a chance that some
+ network operations will not function properly. The Linux
+ TCP/IP layer can compensate in most cases, however, by
+ automatically fragmenting the TCP/IP packets to make them
+ fit. arc0e also works slightly more slowly than arc0, for
+ reasons yet to be determined. (Probably it's the smaller
+ MTU that does it.)
+
+ arc0s The "[s]imple" RFC1051 protocol is the "previous" Internet
+ standard that is completely incompatible with the new
+ standard. Some software today, however, continues to
+ support the old standard (and only the old standard)
+ including NetBSD and AmiTCP. RFC1051 also does not support
+ RFC1201's packet splitting, and the MTU of 507 is still
+ smaller than the Internet "requirement," so it's quite
+ possible that you may run into problems. It's also slower
+ than RFC1201 by about 25%, for the same reason as arc0e.
+
+ The arc0s support was contributed by Tomasz Motylewski
+ and modified somewhat by me. Bugs are probably my fault.
+ ====== ===============================================================
+
+You can choose not to compile arc0e and arc0s into the driver if you want -
+this will save you a bit of memory and avoid confusion when eg. trying to
+use the "NFS-root" stuff in recent Linux kernels.
+
+The arc0e and arc0s devices are created automatically when you first
+ifconfig the arc0 device. To actually use them, though, you need to also
+ifconfig the other virtual devices you need. There are a number of ways you
+can set up your network then:
+
+
+1. Single Protocol.
+
+ This is the simplest way to configure your network: use just one of the
+ two available protocols. As mentioned above, it's a good idea to use
+ only arc0 unless you have a good reason (like some other software, ie.
+ WfWg, that only works with arc0e).
+
+ If you need only arc0, then the following commands should get you going::
+
+ ifconfig arc0 MY.IP.ADD.RESS
+ route add MY.IP.ADD.RESS arc0
+ route add -net SUB.NET.ADD.RESS arc0
+ [add other local routes here]
+
+ If you need arc0e (and only arc0e), it's a little different::
+
+ ifconfig arc0 MY.IP.ADD.RESS
+ ifconfig arc0e MY.IP.ADD.RESS
+ route add MY.IP.ADD.RESS arc0e
+ route add -net SUB.NET.ADD.RESS arc0e
+
+ arc0s works much the same way as arc0e.
+
+
+2. More than one protocol on the same wire.
+
+ Now things start getting confusing. To even try it, you may need to be
+ partly crazy. Here's what *I* did. :) Note that I don't include arc0s in
+ my home network; I don't have any NetBSD or AmiTCP computers, so I only
+ use arc0s during limited testing.
+
+ I have three computers on my home network; two Linux boxes (which prefer
+ RFC1201 protocol, for reasons listed above), and one XT that can't run
+ Linux but runs the free Microsoft LANMAN Client instead.
+
+ Worse, one of the Linux computers (freedom) also has a modem and acts as
+ a router to my Internet provider. The other Linux box (insight) also has
+ its own IP address and needs to use freedom as its default gateway. The
+ XT (patience), however, does not have its own Internet IP address and so
+ I assigned it one on a "private subnet" (as defined by RFC1597).
+
+ To start with, take a simple network with just insight and freedom.
+ Insight needs to:
+
+ - talk to freedom via RFC1201 (arc0) protocol, because I like it
+ more and it's faster.
+ - use freedom as its Internet gateway.
+
+ That's pretty easy to do. Set up insight like this::
+
+ ifconfig arc0 insight
+ route add insight arc0
+ route add freedom arc0 /* I would use the subnet here (like I said
+ to in "single protocol" above),
+ but the rest of the subnet
+ unfortunately lies across the PPP
+ link on freedom, which confuses
+ things. */
+ route add default gw freedom
+
+ And freedom gets configured like so::
+
+ ifconfig arc0 freedom
+ route add freedom arc0
+ route add insight arc0
+ /* and default gateway is configured by pppd */
+
+ Great, now insight talks to freedom directly on arc0, and sends packets
+ to the Internet through freedom. If you didn't know how to do the above,
+ you should probably stop reading this section now because it only gets
+ worse.
+
+ Now, how do I add patience into the network? It will be using LANMAN
+ Client, which means I need the arc0e device. It needs to be able to talk
+ to both insight and freedom, and also use freedom as a gateway to the
+ Internet. (Recall that patience has a "private IP address" which won't
+ work on the Internet; that's okay, I configured Linux IP masquerading on
+ freedom for this subnet).
+
+ So patience (necessarily; I don't have another IP number from my
+ provider) has an IP address on a different subnet than freedom and
+ insight, but needs to use freedom as an Internet gateway. Worse, most
+ DOS networking programs, including LANMAN, have braindead networking
+ schemes that rely completely on the netmask and a 'default gateway' to
+ determine how to route packets. This means that to get to freedom or
+ insight, patience WILL send through its default gateway, regardless of
+ the fact that both freedom and insight (courtesy of the arc0e device)
+ could understand a direct transmission.
+
+ I compensate by giving freedom an extra IP address - aliased 'gatekeeper' -
+ that is on my private subnet, the same subnet that patience is on. I
+ then define gatekeeper to be the default gateway for patience.
+
+ To configure freedom (in addition to the commands above)::
+
+ ifconfig arc0e gatekeeper
+ route add gatekeeper arc0e
+ route add patience arc0e
+
+ This way, freedom will send all packets for patience through arc0e,
+ giving its IP address as gatekeeper (on the private subnet). When it
+ talks to insight or the Internet, it will use its "freedom" Internet IP
+ address.
+
+ You will notice that we haven't configured the arc0e device on insight.
+ This would work, but is not really necessary, and would require me to
+ assign insight another special IP number from my private subnet. Since
+ both insight and patience are using freedom as their default gateway, the
+ two can already talk to each other.
+
+ It's quite fortunate that I set things up like this the first time (cough
+ cough) because it's really handy when I boot insight into DOS. There, it
+ runs the Novell ODI protocol stack, which only works with RFC1201 ARCnet.
+ In this mode it would be impossible for insight to communicate directly
+ with patience, since the Novell stack is incompatible with Microsoft's
+ Ethernet-Encap. Without changing any settings on freedom or patience, I
+ simply set freedom as the default gateway for insight (now in DOS,
+ remember) and all the forwarding happens "automagically" between the two
+ hosts that would normally not be able to communicate at all.
+
+ For those who like diagrams, I have created two "virtual subnets" on the
+ same physical ARCnet wire. You can picture it like this::
+
+
+ [RFC1201 NETWORK] [ETHER-ENCAP NETWORK]
+ (registered Internet subnet) (RFC1597 private subnet)
+
+ (IP Masquerade)
+ /---------------\ * /---------------\
+ | | * | |
+ | +-Freedom-*-Gatekeeper-+ |
+ | | | * | |
+ \-------+-------/ | * \-------+-------/
+ | | |
+ Insight | Patience
+ (Internet)
+
+
+
+It works: what now?
+-------------------
+
+:ref:`Send an email to netdev <arcnet-netdev>`. Describe your setup, preferably
+including driver version, kernel version, ARCnet card model, CPU type, number
+of systems on your network, and list of software in use.
+
+It doesn't work: what now?
+--------------------------
+
+Do the same as above, but also include the output of the ifconfig and route
+commands, as well as any pertinent log entries (ie. anything that starts
+with "arcnet:" and has shown up since the last reboot) in your mail.
+
+If you want to try fixing it yourself (I strongly recommend that you mail me
+about the problem first, since it might already have been solved) you may
+want to try some of the debug levels available. For heavy testing on
+D_DURING or more, it would be a REALLY good idea to kill your klogd daemon
+first! D_DURING displays 4-5 lines for each packet sent or received. D_TX,
+D_RX, and D_SKB actually DISPLAY each packet as it is sent or received,
+which is obviously quite big.
+
+Once the driver is running, you can run the arcdump shell script (available
+from me or in the full ARCnet package, if you have it) as root to list the
+contents of the arcnet buffers at any time. To make any sense at all out of
+this, you should grab the pertinent RFCs. (some are listed near the top of
+arcnet.c). arcdump assumes your card is at 0xD0000. If it isn't, edit the
+script.
+
+Buffers 0 and 1 are used for receiving, and Buffers 2 and 3 are for sending.
+Ping-pong buffers are implemented both ways.
+
+If your debug level includes D_DURING and you did NOT define SLOW_XMIT_COPY,
+the buffers are cleared to a constant value of 0x42 every time the card is
+reset (which should only happen when you do an ifconfig up, or when Linux
+decides that the driver is broken). During a transmit, unused parts of the
+buffer will be cleared to 0x42 as well. This is to make it easier to figure
+out which bytes are being used by a packet.
+
+You can change the debug level without recompiling the kernel by typing::
+
+ ifconfig arc0 down metric 1xxx
+ ifconfig arc0 up
+
+where "xxx" is the debug level you want. For example, "metric 1015" would put
+you at debug level 15. Debug level 7 is currently the default.
+
+Note that the debug level is a binary combination of different debug flags;
+debug level 7 is really 1+2+4 or D_NORMAL+D_EXTRA+D_INIT. To include D_DURING,
+you would add 16 to this, resulting in debug level 23.
+
+If you don't understand that, you probably don't want to know anyway.