From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ... --- Documentation/networking/plip.rst | 222 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 222 insertions(+) create mode 100644 Documentation/networking/plip.rst (limited to 'Documentation/networking/plip.rst') diff --git a/Documentation/networking/plip.rst b/Documentation/networking/plip.rst new file mode 100644 index 000000000..0eda74505 --- /dev/null +++ b/Documentation/networking/plip.rst @@ -0,0 +1,222 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================================ +PLIP: The Parallel Line Internet Protocol Device +================================================ + +Donald Becker (becker@super.org) +I.D.A. Supercomputing Research Center, Bowie MD 20715 + +At some point T. Thorn will probably contribute text, +Tommy Thorn (tthorn@daimi.aau.dk) + +PLIP Introduction +----------------- + +This document describes the parallel port packet pusher for Net/LGX. +This device interface allows a point-to-point connection between two +parallel ports to appear as a IP network interface. + +What is PLIP? +============= + +PLIP is Parallel Line IP, that is, the transportation of IP packages +over a parallel port. In the case of a PC, the obvious choice is the +printer port. PLIP is a non-standard, but [can use] uses the standard +LapLink null-printer cable [can also work in turbo mode, with a PLIP +cable]. [The protocol used to pack IP packages, is a simple one +initiated by Crynwr.] + +Advantages of PLIP +================== + +It's cheap, it's available everywhere, and it's easy. + +The PLIP cable is all that's needed to connect two Linux boxes, and it +can be built for very few bucks. + +Connecting two Linux boxes takes only a second's decision and a few +minutes' work, no need to search for a [supported] netcard. This might +even be especially important in the case of notebooks, where netcards +are not easily available. + +Not requiring a netcard also means that apart from connecting the +cables, everything else is software configuration [which in principle +could be made very easy.] + +Disadvantages of PLIP +===================== + +Doesn't work over a modem, like SLIP and PPP. Limited range, 15 m. +Can only be used to connect three (?) Linux boxes. Doesn't connect to +an existing Ethernet. Isn't standard (not even de facto standard, like +SLIP). + +Performance +=========== + +PLIP easily outperforms Ethernet cards....(ups, I was dreaming, but +it *is* getting late. EOB) + +PLIP driver details +------------------- + +The Linux PLIP driver is an implementation of the original Crynwr protocol, +that uses the parallel port subsystem of the kernel in order to properly +share parallel ports between PLIP and other services. + +IRQs and trigger timeouts +========================= + +When a parallel port used for a PLIP driver has an IRQ configured to it, the +PLIP driver is signaled whenever data is sent to it via the cable, such that +when no data is available, the driver isn't being used. + +However, on some machines it is hard, if not impossible, to configure an IRQ +to a certain parallel port, mainly because it is used by some other device. +On these machines, the PLIP driver can be used in IRQ-less mode, where +the PLIP driver would constantly poll the parallel port for data waiting, +and if such data is available, process it. This mode is less efficient than +the IRQ mode, because the driver has to check the parallel port many times +per second, even when no data at all is sent. Some rough measurements +indicate that there isn't a noticeable performance drop when using IRQ-less +mode as compared to IRQ mode as far as the data transfer speed is involved. +There is a performance drop on the machine hosting the driver. + +When the PLIP driver is used in IRQ mode, the timeout used for triggering a +data transfer (the maximal time the PLIP driver would allow the other side +before announcing a timeout, when trying to handshake a transfer of some +data) is, by default, 500usec. As IRQ delivery is more or less immediate, +this timeout is quite sufficient. + +When in IRQ-less mode, the PLIP driver polls the parallel port HZ times +per second (where HZ is typically 100 on most platforms, and 1024 on an +Alpha, as of this writing). Between two such polls, there are 10^6/HZ usecs. +On an i386, for example, 10^6/100 = 10000usec. It is easy to see that it is +quite possible for the trigger timeout to expire between two such polls, as +the timeout is only 500usec long. As a result, it is required to change the +trigger timeout on the *other* side of a PLIP connection, to about +10^6/HZ usecs. If both sides of a PLIP connection are used in IRQ-less mode, +this timeout is required on both sides. + +It appears that in practice, the trigger timeout can be shorter than in the +above calculation. It isn't an important issue, unless the wire is faulty, +in which case a long timeout would stall the machine when, for whatever +reason, bits are dropped. + +A utility that can perform this change in Linux is plipconfig, which is part +of the net-tools package (its location can be found in the +Documentation/Changes file). An example command would be +'plipconfig plipX trigger 10000', where plipX is the appropriate +PLIP device. + +PLIP hardware interconnection +----------------------------- + +PLIP uses several different data transfer methods. The first (and the +only one implemented in the early version of the code) uses a standard +printer "null" cable to transfer data four bits at a time using +data bit outputs connected to status bit inputs. + +The second data transfer method relies on both machines having +bi-directional parallel ports, rather than output-only ``printer`` +ports. This allows byte-wide transfers and avoids reconstructing +nibbles into bytes, leading to much faster transfers. + +Parallel Transfer Mode 0 Cable +============================== + +The cable for the first transfer mode is a standard +printer "null" cable which transfers data four bits at a time using +data bit outputs of the first port (machine T) connected to the +status bit inputs of the second port (machine R). There are five +status inputs, and they are used as four data inputs and a clock (data +strobe) input, arranged so that the data input bits appear as contiguous +bits with standard status register implementation. + +A cable that implements this protocol is available commercially as a +"Null Printer" or "Turbo Laplink" cable. It can be constructed with +two DB-25 male connectors symmetrically connected as follows:: + + STROBE output 1* + D0->ERROR 2 - 15 15 - 2 + D1->SLCT 3 - 13 13 - 3 + D2->PAPOUT 4 - 12 12 - 4 + D3->ACK 5 - 10 10 - 5 + D4->BUSY 6 - 11 11 - 6 + D5,D6,D7 are 7*, 8*, 9* + AUTOFD output 14* + INIT output 16* + SLCTIN 17 - 17 + extra grounds are 18*,19*,20*,21*,22*,23*,24* + GROUND 25 - 25 + + * Do not connect these pins on either end + +If the cable you are using has a metallic shield it should be +connected to the metallic DB-25 shell at one end only. + +Parallel Transfer Mode 1 +======================== + +The second data transfer method relies on both machines having +bi-directional parallel ports, rather than output-only ``printer`` +ports. This allows byte-wide transfers, and avoids reconstructing +nibbles into bytes. This cable should not be used on unidirectional +``printer`` (as opposed to ``parallel``) ports or when the machine +isn't configured for PLIP, as it will result in output driver +conflicts and the (unlikely) possibility of damage. + +The cable for this transfer mode should be constructed as follows:: + + STROBE->BUSY 1 - 11 + D0->D0 2 - 2 + D1->D1 3 - 3 + D2->D2 4 - 4 + D3->D3 5 - 5 + D4->D4 6 - 6 + D5->D5 7 - 7 + D6->D6 8 - 8 + D7->D7 9 - 9 + INIT -> ACK 16 - 10 + AUTOFD->PAPOUT 14 - 12 + SLCT->SLCTIN 13 - 17 + GND->ERROR 18 - 15 + extra grounds are 19*,20*,21*,22*,23*,24* + GROUND 25 - 25 + + * Do not connect these pins on either end + +Once again, if the cable you are using has a metallic shield it should +be connected to the metallic DB-25 shell at one end only. + +PLIP Mode 0 transfer protocol +============================= + +The PLIP driver is compatible with the "Crynwr" parallel port transfer +standard in Mode 0. That standard specifies the following protocol:: + + send header nibble '0x8' + count-low octet + count-high octet + ... data octets + checksum octet + +Each octet is sent as:: + + + >4)&0x0F)> + +To start a transfer the transmitting machine outputs a nibble 0x08. +That raises the ACK line, triggering an interrupt in the receiving +machine. The receiving machine disables interrupts and raises its own ACK +line. + +Restated:: + + (OUT is bit 0-4, OUT.j is bit j from OUT. IN likewise) + Send_Byte: + OUT := low nibble, OUT.4 := 1 + WAIT FOR IN.4 = 1 + OUT := high nibble, OUT.4 := 0 + WAIT FOR IN.4 = 0 -- cgit v1.2.3