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/blockdev/ramdisk.rst | 153 +++++++++++++++++++++++++ 1 file changed, 153 insertions(+) create mode 100644 Documentation/admin-guide/blockdev/ramdisk.rst (limited to 'Documentation/admin-guide/blockdev/ramdisk.rst') diff --git a/Documentation/admin-guide/blockdev/ramdisk.rst b/Documentation/admin-guide/blockdev/ramdisk.rst new file mode 100644 index 000000000..9ce6101e8 --- /dev/null +++ b/Documentation/admin-guide/blockdev/ramdisk.rst @@ -0,0 +1,153 @@ +========================================== +Using the RAM disk block device with Linux +========================================== + +.. Contents: + + 1) Overview + 2) Kernel Command Line Parameters + 3) Using "rdev" + 4) An Example of Creating a Compressed RAM Disk + + +1) Overview +----------- + +The RAM disk driver is a way to use main system memory as a block device. It +is required for initrd, an initial filesystem used if you need to load modules +in order to access the root filesystem (see Documentation/admin-guide/initrd.rst). It can +also be used for a temporary filesystem for crypto work, since the contents +are erased on reboot. + +The RAM disk dynamically grows as more space is required. It does this by using +RAM from the buffer cache. The driver marks the buffers it is using as dirty +so that the VM subsystem does not try to reclaim them later. + +The RAM disk supports up to 16 RAM disks by default, and can be reconfigured +to support an unlimited number of RAM disks (at your own risk). Just change +the configuration symbol BLK_DEV_RAM_COUNT in the Block drivers config menu +and (re)build the kernel. + +To use RAM disk support with your system, run './MAKEDEV ram' from the /dev +directory. RAM disks are all major number 1, and start with minor number 0 +for /dev/ram0, etc. If used, modern kernels use /dev/ram0 for an initrd. + +The new RAM disk also has the ability to load compressed RAM disk images, +allowing one to squeeze more programs onto an average installation or +rescue floppy disk. + + +2) Parameters +--------------------------------- + +2a) Kernel Command Line Parameters + + ramdisk_size=N + Size of the ramdisk. + +This parameter tells the RAM disk driver to set up RAM disks of N k size. The +default is 4096 (4 MB). + +2b) Module parameters + + rd_nr + /dev/ramX devices created. + + max_part + Maximum partition number. + + rd_size + See ramdisk_size. + +3) Using "rdev" +--------------- + +"rdev" is an obsolete, deprecated, antiquated utility that could be used +to set the boot device in a Linux kernel image. + +Instead of using rdev, just place the boot device information on the +kernel command line and pass it to the kernel from the bootloader. + +You can also pass arguments to the kernel by setting FDARGS in +arch/x86/boot/Makefile and specify in initrd image by setting FDINITRD in +arch/x86/boot/Makefile. + +Some of the kernel command line boot options that may apply here are:: + + ramdisk_start=N + ramdisk_size=M + +If you make a boot disk that has LILO, then for the above, you would use:: + + append = "ramdisk_start=N ramdisk_size=M" + +4) An Example of Creating a Compressed RAM Disk +----------------------------------------------- + +To create a RAM disk image, you will need a spare block device to +construct it on. This can be the RAM disk device itself, or an +unused disk partition (such as an unmounted swap partition). For this +example, we will use the RAM disk device, "/dev/ram0". + +Note: This technique should not be done on a machine with less than 8 MB +of RAM. If using a spare disk partition instead of /dev/ram0, then this +restriction does not apply. + +a) Decide on the RAM disk size that you want. Say 2 MB for this example. + Create it by writing to the RAM disk device. (This step is not currently + required, but may be in the future.) It is wise to zero out the + area (esp. for disks) so that maximal compression is achieved for + the unused blocks of the image that you are about to create:: + + dd if=/dev/zero of=/dev/ram0 bs=1k count=2048 + +b) Make a filesystem on it. Say ext2fs for this example:: + + mke2fs -vm0 /dev/ram0 2048 + +c) Mount it, copy the files you want to it (eg: /etc/* /dev/* ...) + and unmount it again. + +d) Compress the contents of the RAM disk. The level of compression + will be approximately 50% of the space used by the files. Unused + space on the RAM disk will compress to almost nothing:: + + dd if=/dev/ram0 bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz + +e) Put the kernel onto the floppy:: + + dd if=zImage of=/dev/fd0 bs=1k + +f) Put the RAM disk image onto the floppy, after the kernel. Use an offset + that is slightly larger than the kernel, so that you can put another + (possibly larger) kernel onto the same floppy later without overlapping + the RAM disk image. An offset of 400 kB for kernels about 350 kB in + size would be reasonable. Make sure offset+size of ram_image.gz is + not larger than the total space on your floppy (usually 1440 kB):: + + dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400 + +g) Make sure that you have already specified the boot information in + FDARGS and FDINITRD or that you use a bootloader to pass kernel + command line boot options to the kernel. + +That is it. You now have your boot/root compressed RAM disk floppy. Some +users may wish to combine steps (d) and (f) by using a pipe. + + + Paul Gortmaker 12/95 + +Changelog: +---------- + +SEPT-2020 : + + Removed usage of "rdev" + +10-22-04 : + Updated to reflect changes in command line options, remove + obsolete references, general cleanup. + James Nelson (james4765@gmail.com) + +12-95 : + Original Document -- cgit v1.2.3