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/admin-guide/media/faq.rst | 216 ++++++++++++++++++++++++++++++++ 1 file changed, 216 insertions(+) create mode 100644 Documentation/admin-guide/media/faq.rst (limited to 'Documentation/admin-guide/media/faq.rst') diff --git a/Documentation/admin-guide/media/faq.rst b/Documentation/admin-guide/media/faq.rst new file mode 100644 index 000000000..b63548b6f --- /dev/null +++ b/Documentation/admin-guide/media/faq.rst @@ -0,0 +1,216 @@ +.. SPDX-License-Identifier: GPL-2.0 + +FAQ +=== + +.. note:: + + 1. With Digital TV, a single physical channel may have different + contents inside it. The specs call each one as a *service*. + This is what a TV user would call "channel". So, in order to + avoid confusion, we're calling *transponders* as the physical + channel on this FAQ, and *services* for the logical channel. + 2. The LinuxTV community maintains some Wiki pages with contain + a lot of information related to the media subsystem. If you + don't find an answer for your needs here, it is likely that + you'll be able to get something useful there. It is hosted + at: + + https://www.linuxtv.org/wiki/ + +Some very frequently asked questions about Linux Digital TV support + +1. The signal seems to die a few seconds after tuning. + + It's not a bug, it's a feature. Because the frontends have + significant power requirements (and hence get very hot), they + are powered down if they are unused (i.e. if the frontend device + is closed). The ``dvb-core`` module parameter ``dvb_shutdown_timeout`` + allow you to change the timeout (default 5 seconds). Setting the + timeout to 0 disables the timeout feature. + +2. How can I watch TV? + + Together with the Linux Kernel, the Digital TV developers support + some simple utilities which are mainly intended for testing + and to demonstrate how the DVB API works. This is called DVB v5 + tools and are grouped together with the ``v4l-utils`` git repository: + + https://git.linuxtv.org/v4l-utils.git/ + + You can find more information at the LinuxTV wiki: + + https://www.linuxtv.org/wiki/index.php/DVBv5_Tools + + The first step is to get a list of services that are transmitted. + + This is done by using several existing tools. You can use + for example the ``dvbv5-scan`` tool. You can find more information + about it at: + + https://www.linuxtv.org/wiki/index.php/Dvbv5-scan + + There are some other applications like ``w_scan`` [#]_ that do a + blind scan, trying hard to find all possible channels, but + those consumes a large amount of time to run. + + .. [#] https://www.linuxtv.org/wiki/index.php/W_scan + + Also, some applications like ``kaffeine`` have their own code + to scan for services. So, you don't need to use an external + application to obtain such list. + + Most of such tools need a file containing a list of channel + transponders available on your area. So, LinuxTV developers + maintain tables of Digital TV channel transponders, receiving + patches from the community to keep them updated. + + This list is hosted at: + + https://git.linuxtv.org/dtv-scan-tables.git + + And packaged on several distributions. + + Kaffeine has some blind scan support for some terrestrial standards. + It also relies on DTV scan tables, although it contains a copy + of it internally (and, if requested by the user, it will download + newer versions of it). + + If you are lucky you can just use one of the supplied channel + transponders. If not, you may need to seek for such info at + the Internet and create a new file. There are several sites with + contains physical channel lists. For cable and satellite, usually + knowing how to tune into a single channel is enough for the + scanning tool to identify the other channels. On some places, + this could also work for terrestrial transmissions. + + Once you have a transponders list, you need to generate a services + list with a tool like ``dvbv5-scan``. + + Almost all modern Digital TV cards don't have built-in hardware + MPEG-decoders. So, it is up to the application to get a MPEG-TS + stream provided by the board, split it into audio, video and other + data and decode. + +3. Which Digital TV applications exist? + + Several media player applications are capable of tuning into + digital TV channels, including Kaffeine, Vlc, mplayer and MythTV. + + Kaffeine aims to be very user-friendly, and it is maintained + by one of the Kernel driver developers. + + A comprehensive list of those and other apps can be found at: + + https://www.linuxtv.org/wiki/index.php/TV_Related_Software + + Some of the most popular ones are linked below: + + https://kde.org/applications/multimedia/org.kde.kaffeine + KDE media player, focused on Digital TV support + + https://www.linuxtv.org/vdrwiki/index.php/Main_Page + Klaus Schmidinger's Video Disk Recorder + + https://linuxtv.org/downloads and https://git.linuxtv.org/ + Digital TV and other media-related applications and + Kernel drivers. The ``v4l-utils`` package there contains + several swiss knife tools for using with Digital TV. + + http://sourceforge.net/projects/dvbtools/ + Dave Chapman's dvbtools package, including + dvbstream and dvbtune + + http://www.dbox2.info/ + LinuxDVB on the dBox2 + + http://www.tuxbox.org/ + the TuxBox CVS many interesting DVB applications and the dBox2 + DVB source + + http://www.nenie.org/misc/mpsys/ + MPSYS: a MPEG2 system library and tools + + https://www.videolan.org/vlc/index.pt.html + Vlc + + http://mplayerhq.hu/ + MPlayer + + http://xine.sourceforge.net/ and http://xinehq.de/ + Xine + + http://www.mythtv.org/ + MythTV - analog TV and digital TV PVR + + http://dvbsnoop.sourceforge.net/ + DVB sniffer program to monitor, analyze, debug, dump + or view dvb/mpeg/dsm-cc/mhp stream information (TS, + PES, SECTION) + +4. Can't get a signal tuned correctly + + That could be due to a lot of problems. On my personal experience, + usually TV cards need stronger signals than TV sets, and are more + sensitive to noise. So, perhaps you just need a better antenna or + cabling. Yet, it could also be some hardware or driver issue. + + For example, if you are using a Technotrend/Hauppauge DVB-C card + *without* analog module, you might have to use module parameter + adac=-1 (dvb-ttpci.o). + + Please see the FAQ page at linuxtv.org, as it could contain some + valuable information: + + https://www.linuxtv.org/wiki/index.php/FAQ_%26_Troubleshooting + + If that doesn't work, check at the linux-media ML archives, to + see if someone else had a similar problem with your hardware + and/or digital TV service provider: + + https://lore.kernel.org/linux-media/ + + If none of this works, you can try sending an e-mail to the + linux-media ML and see if someone else could shed some light. + The e-mail is linux-media AT vger.kernel.org. + +5. The dvb_net device doesn't give me any packets at all + + Run ``tcpdump`` on the ``dvb0_0`` interface. This sets the interface + into promiscuous mode so it accepts any packets from the PID + you have configured with the ``dvbnet`` utility. Check if there + are any packets with the IP addr and MAC addr you have + configured with ``ifconfig`` or with ``ip addr``. + + If ``tcpdump`` doesn't give you any output, check the statistics + which ``ifconfig`` or ``netstat -ni`` outputs. (Note: If the MAC + address is wrong, ``dvb_net`` won't get any input; thus you have to + run ``tcpdump`` before checking the statistics.) If there are no + packets at all then maybe the PID is wrong. If there are error packets, + then either the PID is wrong or the stream does not conform to + the MPE standard (EN 301 192, http://www.etsi.org/). You can + use e.g. ``dvbsnoop`` for debugging. + +6. The ``dvb_net`` device doesn't give me any multicast packets + + Check your routes if they include the multicast address range. + Additionally make sure that "source validation by reversed path + lookup" is disabled:: + + $ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter" + +7. What are all those modules that need to be loaded? + + In order to make it more flexible and support different hardware + combinations, the media subsystem is written on a modular way. + + So, besides the Digital TV hardware module for the main chipset, + it also needs to load a frontend driver, plus the Digital TV + core. If the board also has remote controller, it will also + need the remote controller core and the remote controller tables. + The same happens if the board has support for analog TV: the + core support for video4linux need to be loaded. + + The actual module names are Linux-kernel version specific, as, + from time to time, things change, in order to make the media + support more flexible. -- cgit v1.2.3