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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/core-api/librs.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
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().
...
Diffstat (limited to 'Documentation/core-api/librs.rst')
-rw-r--r-- | Documentation/core-api/librs.rst | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/Documentation/core-api/librs.rst b/Documentation/core-api/librs.rst new file mode 100644 index 000000000..6010f5bc5 --- /dev/null +++ b/Documentation/core-api/librs.rst @@ -0,0 +1,212 @@ +========================================== +Reed-Solomon Library Programming Interface +========================================== + +:Author: Thomas Gleixner + +Introduction +============ + +The generic Reed-Solomon Library provides encoding, decoding and error +correction functions. + +Reed-Solomon codes are used in communication and storage applications to +ensure data integrity. + +This documentation is provided for developers who want to utilize the +functions provided by the library. + +Known Bugs And Assumptions +========================== + +None. + +Usage +===== + +This chapter provides examples of how to use the library. + +Initializing +------------ + +The init function init_rs returns a pointer to an rs decoder structure, +which holds the necessary information for encoding, decoding and error +correction with the given polynomial. It either uses an existing +matching decoder or creates a new one. On creation all the lookup tables +for fast en/decoding are created. The function may take a while, so make +sure not to call it in critical code paths. + +:: + + /* the Reed Solomon control structure */ + static struct rs_control *rs_decoder; + + /* Symbolsize is 10 (bits) + * Primitive polynomial is x^10+x^3+1 + * first consecutive root is 0 + * primitive element to generate roots = 1 + * generator polynomial degree (number of roots) = 6 + */ + rs_decoder = init_rs (10, 0x409, 0, 1, 6); + + +Encoding +-------- + +The encoder calculates the Reed-Solomon code over the given data length +and stores the result in the parity buffer. Note that the parity buffer +must be initialized before calling the encoder. + +The expanded data can be inverted on the fly by providing a non-zero +inversion mask. The expanded data is XOR'ed with the mask. This is used +e.g. for FLASH ECC, where the all 0xFF is inverted to an all 0x00. The +Reed-Solomon code for all 0x00 is all 0x00. The code is inverted before +storing to FLASH so it is 0xFF too. This prevents that reading from an +erased FLASH results in ECC errors. + +The databytes are expanded to the given symbol size on the fly. There is +no support for encoding continuous bitstreams with a symbol size != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + /* Initialize the parity buffer */ + memset(par, 0, sizeof(par)); + /* Encode 512 byte in data8. Store parity in buffer par */ + encode_rs8 (rs_decoder, data8, 512, par, 0); + + +Decoding +-------- + +The decoder calculates the syndrome over the given data length and the +received parity symbols and corrects errors in the data. + +If a syndrome is available from a hardware decoder then the syndrome +calculation is skipped. + +The correction of the data buffer can be suppressed by providing a +correction pattern buffer and an error location buffer to the decoder. +The decoder stores the calculated error location and the correction +bitmask in the given buffers. This is useful for hardware decoders which +use a weird bit ordering scheme. + +The databytes are expanded to the given symbol size on the fly. There is +no support for decoding continuous bitstreams with a symbolsize != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +Decoding with syndrome calculation, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, NULL, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, syn, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, no direct data correction. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Note: It's not necessary to give data and received parity to the +decoder. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6], corr[8]; + uint8_t data[512]; + int numerr, errpos[8]; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, NULL, NULL, 512, syn, 0, errpos, 0, corr); + for (i = 0; i < numerr; i++) { + do_error_correction_in_your_buffer(errpos[i], corr[i]); + } + + +Cleanup +------- + +The function free_rs frees the allocated resources, if the caller is +the last user of the decoder. + +:: + + /* Release resources */ + free_rs(rs_decoder); + + +Structures +========== + +This chapter contains the autogenerated documentation of the structures +which are used in the Reed-Solomon Library and are relevant for a +developer. + +.. kernel-doc:: include/linux/rslib.h + :internal: + +Public Functions Provided +========================= + +This chapter contains the autogenerated documentation of the +Reed-Solomon functions which are exported. + +.. kernel-doc:: lib/reed_solomon/reed_solomon.c + :export: + +Credits +======= + +The library code for encoding and decoding was written by Phil Karn. + +:: + + Copyright 2002, Phil Karn, KA9Q + May be used under the terms of the GNU General Public License (GPL) + + +The wrapper functions and interfaces are written by Thomas Gleixner. + +Many users have provided bugfixes, improvements and helping hands for +testing. Thanks a lot. + +The following people have contributed to this document: + +Thomas Gleixner\ tglx@linutronix.de |