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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/driver-api/scsi.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/driver-api/scsi.rst')
-rw-r--r-- | Documentation/driver-api/scsi.rst | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/Documentation/driver-api/scsi.rst b/Documentation/driver-api/scsi.rst new file mode 100644 index 000000000..64b231d12 --- /dev/null +++ b/Documentation/driver-api/scsi.rst @@ -0,0 +1,338 @@ +===================== +SCSI Interfaces Guide +===================== + +:Author: James Bottomley +:Author: Rob Landley + +Introduction +============ + +Protocol vs bus +--------------- + +Once upon a time, the Small Computer Systems Interface defined both a +parallel I/O bus and a data protocol to connect a wide variety of +peripherals (disk drives, tape drives, modems, printers, scanners, +optical drives, test equipment, and medical devices) to a host computer. + +Although the old parallel (fast/wide/ultra) SCSI bus has largely fallen +out of use, the SCSI command set is more widely used than ever to +communicate with devices over a number of different busses. + +The `SCSI protocol <http://www.t10.org/scsi-3.htm>`__ is a big-endian +peer-to-peer packet based protocol. SCSI commands are 6, 10, 12, or 16 +bytes long, often followed by an associated data payload. + +SCSI commands can be transported over just about any kind of bus, and +are the default protocol for storage devices attached to USB, SATA, SAS, +Fibre Channel, FireWire, and ATAPI devices. SCSI packets are also +commonly exchanged over Infiniband, +`I2O <http://i2o.shadowconnect.com/faq.php>`__, TCP/IP +(`iSCSI <https://en.wikipedia.org/wiki/ISCSI>`__), even `Parallel +ports <http://cyberelk.net/tim/parport/parscsi.html>`__. + +Design of the Linux SCSI subsystem +---------------------------------- + +The SCSI subsystem uses a three layer design, with upper, mid, and low +layers. Every operation involving the SCSI subsystem (such as reading a +sector from a disk) uses one driver at each of the 3 levels: one upper +layer driver, one lower layer driver, and the SCSI midlayer. + +The SCSI upper layer provides the interface between userspace and the +kernel, in the form of block and char device nodes for I/O and ioctl(). +The SCSI lower layer contains drivers for specific hardware devices. + +In between is the SCSI mid-layer, analogous to a network routing layer +such as the IPv4 stack. The SCSI mid-layer routes a packet based data +protocol between the upper layer's /dev nodes and the corresponding +devices in the lower layer. It manages command queues, provides error +handling and power management functions, and responds to ioctl() +requests. + +SCSI upper layer +================ + +The upper layer supports the user-kernel interface by providing device +nodes. + +sd (SCSI Disk) +-------------- + +sd (sd_mod.o) + +sr (SCSI CD-ROM) +---------------- + +sr (sr_mod.o) + +st (SCSI Tape) +-------------- + +st (st.o) + +sg (SCSI Generic) +----------------- + +sg (sg.o) + +ch (SCSI Media Changer) +----------------------- + +ch (ch.c) + +SCSI mid layer +============== + +SCSI midlayer implementation +---------------------------- + +include/scsi/scsi_device.h +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/scsi/scsi_device.h + :internal: + +drivers/scsi/scsi.c +~~~~~~~~~~~~~~~~~~~ + +Main file for the SCSI midlayer. + +.. kernel-doc:: drivers/scsi/scsi.c + :export: + +drivers/scsi/scsicam.c +~~~~~~~~~~~~~~~~~~~~~~ + +`SCSI Common Access +Method <http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf>`__ support +functions, for use with HDIO_GETGEO, etc. + +.. kernel-doc:: drivers/scsi/scsicam.c + :export: + +drivers/scsi/scsi_error.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Common SCSI error/timeout handling routines. + +.. kernel-doc:: drivers/scsi/scsi_error.c + :export: + +drivers/scsi/scsi_devinfo.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Manage scsi_dev_info_list, which tracks blacklisted and whitelisted +devices. + +.. kernel-doc:: drivers/scsi/scsi_devinfo.c + :internal: + +drivers/scsi/scsi_ioctl.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Handle ioctl() calls for SCSI devices. + +.. kernel-doc:: drivers/scsi/scsi_ioctl.c + :export: + +drivers/scsi/scsi_lib.c +~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI queuing library. + +.. kernel-doc:: drivers/scsi/scsi_lib.c + :export: + +drivers/scsi/scsi_lib_dma.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI library functions depending on DMA (map and unmap scatter-gather +lists). + +.. kernel-doc:: drivers/scsi/scsi_lib_dma.c + :export: + +drivers/scsi/scsi_proc.c +~~~~~~~~~~~~~~~~~~~~~~~~~ + +The functions in this file provide an interface between the PROC file +system and the SCSI device drivers It is mainly used for debugging, +statistics and to pass information directly to the lowlevel driver. I.E. +plumbing to manage /proc/scsi/\* + +.. kernel-doc:: drivers/scsi/scsi_proc.c + :internal: + +drivers/scsi/scsi_netlink.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Infrastructure to provide async events from transports to userspace via +netlink, using a single NETLINK_SCSITRANSPORT protocol for all +transports. See `the original patch +submission <http://marc.info/?l=linux-scsi&m=115507374832500&w=2>`__ for +more details. + +.. kernel-doc:: drivers/scsi/scsi_netlink.c + :internal: + +drivers/scsi/scsi_scan.c +~~~~~~~~~~~~~~~~~~~~~~~~~ + +Scan a host to determine which (if any) devices are attached. The +general scanning/probing algorithm is as follows, exceptions are made to +it depending on device specific flags, compilation options, and global +variable (boot or module load time) settings. A specific LUN is scanned +via an INQUIRY command; if the LUN has a device attached, a scsi_device +is allocated and setup for it. For every id of every channel on the +given host, start by scanning LUN 0. Skip hosts that don't respond at +all to a scan of LUN 0. Otherwise, if LUN 0 has a device attached, +allocate and setup a scsi_device for it. If target is SCSI-3 or up, +issue a REPORT LUN, and scan all of the LUNs returned by the REPORT LUN; +else, sequentially scan LUNs up until some maximum is reached, or a LUN +is seen that cannot have a device attached to it. + +.. kernel-doc:: drivers/scsi/scsi_scan.c + :internal: + +drivers/scsi/scsi_sysctl.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Set up the sysctl entry: "/dev/scsi/logging_level" +(DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level. + +drivers/scsi/scsi_sysfs.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI sysfs interface routines. + +.. kernel-doc:: drivers/scsi/scsi_sysfs.c + :export: + +drivers/scsi/hosts.c +~~~~~~~~~~~~~~~~~~~~ + +mid to lowlevel SCSI driver interface + +.. kernel-doc:: drivers/scsi/hosts.c + :export: + +drivers/scsi/scsi_common.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +general support functions + +.. kernel-doc:: drivers/scsi/scsi_common.c + :export: + +Transport classes +----------------- + +Transport classes are service libraries for drivers in the SCSI lower +layer, which expose transport attributes in sysfs. + +Fibre Channel transport +~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_fc.c defines transport attributes +for Fibre Channel. + +.. kernel-doc:: drivers/scsi/scsi_transport_fc.c + :export: + +iSCSI transport class +~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_iscsi.c defines transport +attributes for the iSCSI class, which sends SCSI packets over TCP/IP +connections. + +.. kernel-doc:: drivers/scsi/scsi_transport_iscsi.c + :export: + +Serial Attached SCSI (SAS) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_sas.c defines transport +attributes for Serial Attached SCSI, a variant of SATA aimed at large +high-end systems. + +The SAS transport class contains common code to deal with SAS HBAs, an +aproximated representation of SAS topologies in the driver model, and +various sysfs attributes to expose these topologies and management +interfaces to userspace. + +In addition to the basic SCSI core objects this transport class +introduces two additional intermediate objects: The SAS PHY as +represented by struct sas_phy defines an "outgoing" PHY on a SAS HBA or +Expander, and the SAS remote PHY represented by struct sas_rphy defines +an "incoming" PHY on a SAS Expander or end device. Note that this is +purely a software concept, the underlying hardware for a PHY and a +remote PHY is the exactly the same. + +There is no concept of a SAS port in this code, users can see what PHYs +form a wide port based on the port_identifier attribute, which is the +same for all PHYs in a port. + +.. kernel-doc:: drivers/scsi/scsi_transport_sas.c + :export: + +SATA transport class +~~~~~~~~~~~~~~~~~~~~ + +The SATA transport is handled by libata, which has its own book of +documentation in this directory. + +Parallel SCSI (SPI) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_spi.c defines transport +attributes for traditional (fast/wide/ultra) SCSI busses. + +.. kernel-doc:: drivers/scsi/scsi_transport_spi.c + :export: + +SCSI RDMA (SRP) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_srp.c defines transport +attributes for SCSI over Remote Direct Memory Access. + +.. kernel-doc:: drivers/scsi/scsi_transport_srp.c + :export: + +SCSI lower layer +================ + +Host Bus Adapter transport types +-------------------------------- + +Many modern device controllers use the SCSI command set as a protocol to +communicate with their devices through many different types of physical +connections. + +In SCSI language a bus capable of carrying SCSI commands is called a +"transport", and a controller connecting to such a bus is called a "host +bus adapter" (HBA). + +Debug transport +~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_debug.c simulates a host adapter with a +variable number of disks (or disk like devices) attached, sharing a +common amount of RAM. Does a lot of checking to make sure that we are +not getting blocks mixed up, and panics the kernel if anything out of +the ordinary is seen. + +To be more realistic, the simulated devices have the transport +attributes of SAS disks. + +For documentation see http://sg.danny.cz/sg/sdebug26.html + +todo +~~~~ + +Parallel (fast/wide/ultra) SCSI, USB, SATA, SAS, Fibre Channel, +FireWire, ATAPI devices, Infiniband, I2O, Parallel ports, +netlink... |