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(). ... --- .../early-userspace/early_userspace_support.rst | 154 +++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 Documentation/driver-api/early-userspace/early_userspace_support.rst (limited to 'Documentation/driver-api/early-userspace/early_userspace_support.rst') diff --git a/Documentation/driver-api/early-userspace/early_userspace_support.rst b/Documentation/driver-api/early-userspace/early_userspace_support.rst new file mode 100644 index 000000000..61bdeac1b --- /dev/null +++ b/Documentation/driver-api/early-userspace/early_userspace_support.rst @@ -0,0 +1,154 @@ +======================= +Early userspace support +======================= + +Last update: 2004-12-20 tlh + + +"Early userspace" is a set of libraries and programs that provide +various pieces of functionality that are important enough to be +available while a Linux kernel is coming up, but that don't need to be +run inside the kernel itself. + +It consists of several major infrastructure components: + +- gen_init_cpio, a program that builds a cpio-format archive + containing a root filesystem image. This archive is compressed, and + the compressed image is linked into the kernel image. +- initramfs, a chunk of code that unpacks the compressed cpio image + midway through the kernel boot process. +- klibc, a userspace C library, currently packaged separately, that is + optimized for correctness and small size. + +The cpio file format used by initramfs is the "newc" (aka "cpio -H newc") +format, and is documented in the file "buffer-format.txt". There are +two ways to add an early userspace image: specify an existing cpio +archive to be used as the image or have the kernel build process build +the image from specifications. + +CPIO ARCHIVE method +------------------- + +You can create a cpio archive that contains the early userspace image. +Your cpio archive should be specified in CONFIG_INITRAMFS_SOURCE and it +will be used directly. Only a single cpio file may be specified in +CONFIG_INITRAMFS_SOURCE and directory and file names are not allowed in +combination with a cpio archive. + +IMAGE BUILDING method +--------------------- + +The kernel build process can also build an early userspace image from +source parts rather than supplying a cpio archive. This method provides +a way to create images with root-owned files even though the image was +built by an unprivileged user. + +The image is specified as one or more sources in +CONFIG_INITRAMFS_SOURCE. Sources can be either directories or files - +cpio archives are *not* allowed when building from sources. + +A source directory will have it and all of its contents packaged. The +specified directory name will be mapped to '/'. When packaging a +directory, limited user and group ID translation can be performed. +INITRAMFS_ROOT_UID can be set to a user ID that needs to be mapped to +user root (0). INITRAMFS_ROOT_GID can be set to a group ID that needs +to be mapped to group root (0). + +A source file must be directives in the format required by the +usr/gen_init_cpio utility (run 'usr/gen_init_cpio -h' to get the +file format). The directives in the file will be passed directly to +usr/gen_init_cpio. + +When a combination of directories and files are specified then the +initramfs image will be an aggregate of all of them. In this way a user +can create a 'root-image' directory and install all files into it. +Because device-special files cannot be created by a unprivileged user, +special files can be listed in a 'root-files' file. Both 'root-image' +and 'root-files' can be listed in CONFIG_INITRAMFS_SOURCE and a complete +early userspace image can be built by an unprivileged user. + +As a technical note, when directories and files are specified, the +entire CONFIG_INITRAMFS_SOURCE is passed to +usr/gen_initramfs.sh. This means that CONFIG_INITRAMFS_SOURCE +can really be interpreted as any legal argument to +gen_initramfs.sh. If a directory is specified as an argument then +the contents are scanned, uid/gid translation is performed, and +usr/gen_init_cpio file directives are output. If a directory is +specified as an argument to usr/gen_initramfs.sh then the +contents of the file are simply copied to the output. All of the output +directives from directory scanning and file contents copying are +processed by usr/gen_init_cpio. + +See also 'usr/gen_initramfs.sh -h'. + +Where's this all leading? +========================= + +The klibc distribution contains some of the necessary software to make +early userspace useful. The klibc distribution is currently +maintained separately from the kernel. + +You can obtain somewhat infrequent snapshots of klibc from +https://www.kernel.org/pub/linux/libs/klibc/ + +For active users, you are better off using the klibc git +repository, at https://git.kernel.org/?p=libs/klibc/klibc.git + +The standalone klibc distribution currently provides three components, +in addition to the klibc library: + +- ipconfig, a program that configures network interfaces. It can + configure them statically, or use DHCP to obtain information + dynamically (aka "IP autoconfiguration"). +- nfsmount, a program that can mount an NFS filesystem. +- kinit, the "glue" that uses ipconfig and nfsmount to replace the old + support for IP autoconfig, mount a filesystem over NFS, and continue + system boot using that filesystem as root. + +kinit is built as a single statically linked binary to save space. + +Eventually, several more chunks of kernel functionality will hopefully +move to early userspace: + +- Almost all of init/do_mounts* (the beginning of this is already in + place) +- ACPI table parsing +- Insert unwieldy subsystem that doesn't really need to be in kernel + space here + +If kinit doesn't meet your current needs and you've got bytes to burn, +the klibc distribution includes a small Bourne-compatible shell (ash) +and a number of other utilities, so you can replace kinit and build +custom initramfs images that meet your needs exactly. + +For questions and help, you can sign up for the early userspace +mailing list at https://www.zytor.com/mailman/listinfo/klibc + +How does it work? +================= + +The kernel has currently 3 ways to mount the root filesystem: + +a) all required device and filesystem drivers compiled into the kernel, no + initrd. init/main.c:init() will call prepare_namespace() to mount the + final root filesystem, based on the root= option and optional init= to run + some other init binary than listed at the end of init/main.c:init(). + +b) some device and filesystem drivers built as modules and stored in an + initrd. The initrd must contain a binary '/linuxrc' which is supposed to + load these driver modules. It is also possible to mount the final root + filesystem via linuxrc and use the pivot_root syscall. The initrd is + mounted and executed via prepare_namespace(). + +c) using initramfs. The call to prepare_namespace() must be skipped. + This means that a binary must do all the work. Said binary can be stored + into initramfs either via modifying usr/gen_init_cpio.c or via the new + initrd format, an cpio archive. It must be called "/init". This binary + is responsible to do all the things prepare_namespace() would do. + + To maintain backwards compatibility, the /init binary will only run if it + comes via an initramfs cpio archive. If this is not the case, + init/main.c:init() will run prepare_namespace() to mount the final root + and exec one of the predefined init binaries. + +Bryan O'Sullivan -- cgit v1.2.3