Linux 4.2 [https://lkml.org/lkml/2015/8/30/96 has been released] on 30 Aug 2015

Warning This page will be completed in the future (it will, really)

1. Prominent features

2. Drivers and architectures

• All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_4.2-DriversArch Linux_4.2-DriversArch] page.

3. Core (various)

• FS-Cache: Count culled objects and objects rejected due to lack of space, and the number of initialised operations, and show them in /proc/fs/fscache/stats [https://git.kernel.org/torvalds/c/03cdd0e4b9a98ae995b81cd8f58e992ec3f44ae2 commit], [https://git.kernel.org/torvalds/c/182d919b84902eece162c63ed3d476c8016b4197 commit]

• Allow drivers request for their probe functions to be called asynchronously during driver and device registration (manual binding is still synchronous) [https://git.kernel.org/torvalds/c/765230b5f084863183aa8adb3405ab3f32c0b16e commit], [https://git.kernel.org/torvalds/c/f2411da746985e60d4d087f3a43e271c61785927 commit], [https://git.kernel.org/torvalds/c/d173a137c5bd95ee29d02705e5fa8890ef149718 commit]

4. File systems

• BTRFS

  • Let btree defrag work in SSD mode [https://git.kernel.org/torvalds/c/13028901a4a62096e97a0fc44388ea859587f690 commit]

  • Allow unprivileged query of the root id of the containing subvolume with the INO_LOOKUP ioctl [https://git.kernel.org/torvalds/c/01b810b889d557257580970e1a7ba9c85b54766b commit]

  • Show "subvol=" and "subvolid=" in /proc/mounts [https://git.kernel.org/torvalds/c/c8d3fe028f64054d75c72566efb9ecf3c75ee161 commit]

• CIFS

  • Add (minimal) support for the new protocol dialect, SMB3.1.1 [https://git.kernel.org/torvalds/c/aab1893d5fbeb7c931e97189f54a71ab0ecbf4c7 commit], [https://git.kernel.org/torvalds/c/eed0e1753cbe7a30758ad2ee5e2742dd7fda2c41 commit], [https://git.kernel.org/torvalds/c/ebb3a9d4ba3babd19c83b96fc88fc9b0d2f7d2d6 commit], [https://git.kernel.org/torvalds/c/5f7fbf733c9dd6b58d40fa394313a5949b696f84 commit]

  • Add reflink copy support (cp --reflink ) over SMB3.11 [https://git.kernel.org/torvalds/c/02b1666544c08e245cb4e2253ed575f8128943d6 commit]

  • Add ioctl CIFS_IOC_SET_INTEGRITY to set integrity. Set integrity increases reliability of files stored on SMB3 servers [https://git.kernel.org/torvalds/c/b3152e2c7aa9ad0c50085738d048fbf16d01d32d commit]

• GFS2

  • Add support for rename2 and RENAME_EXCHANGE [https://git.kernel.org/torvalds/c/a63b7bbc2175901d79fa36ba734499655c077f0d commit]

• NFS

  • NFSv4.2 LAYOUTSTATS functionality for pnfs flexfiles [https://git.kernel.org/torvalds/c/122d328d303afaa06ad530ca0b2e5be3cd50a1a5 (merge)]

• NILFS2

  • Support NFSv2 export [https://git.kernel.org/torvalds/c/f73c2f1f83ca1c4e2f4515f987973bfe56c86973 commit]

• UDF

  • Support NFSv2 export [https://git.kernel.org/torvalds/c/92acca45428f28c0b387f85b52b230d526dd0ecc commit]

5. Memory management

6. Block layer

• Make CFQ default to IOPS mode on SSDs [https://git.kernel.org/torvalds/c/41c0126b3f22ef36b97b3c38b8f29569848a5ce2 commit]

• Addition of policy specific data to blkcg for block cgroups [https://git.kernel.org/torvalds/c/e48453c386f39ca9ea29e9df6efef78f56746af0 commit]

• Add support for DAX reads/writes to block devices [https://git.kernel.org/torvalds/c/bbab37ddc20bae4709bca8745c128c4f46fe63c5 commit]

• UBI: Dynamically allocate minor numbers [https://git.kernel.org/torvalds/c/2bf50d42f3a418153d2964ca0f25655177f36445 commit]

• Device mapper

  • dm raid: Add dm-raid access to the MD RAID0 personality to enable single zone striping [https://git.kernel.org/torvalds/c/0cf4503174c12025ac7ea61048cb7c1d4d1ed85c commit]

  • dm cache: Add fail io mode and needs_check flag: If a cache metadata operation fails (e.g. transaction commit) the cache's metadata device will abort the current transaction, set a new needs_check flag, and the cache will transition to "read-only" mode [https://git.kernel.org/torvalds/c/028ae9f76f2935e8cf9974bff9a4587e3a995ff3 commit]

  • dm cache: add stochastic-multi-queue (smq) policy, make it default: The stochastic-multi-queue (smq) policy addresses some of the problems with the current multiqueue (mq) policy (memory usage, level balancing, adaptability, performance) [https://git.kernel.org/torvalds/c/66a636356647a9be8885c2ce2948de126577698a commit], [https://git.kernel.org/torvalds/c/bccab6a01afc26f53d91762d78153513cad10b29 commit]

  • dm stats: add support for request-based DM devices (eg. multipath) [https://git.kernel.org/torvalds/c/e262f34741522e0d821642e5449c6eeb512723fc commit]

  • dm stats: add option to dm statistics to collect and report a histogram of IO latencies [https://git.kernel.org/torvalds/c/dfcfac3e4cd94abef779297fab6adfd2dbcf52fa commit]

  • dm stats: Make it possible to use precise timestamps with nanosecond granularity [https://git.kernel.org/torvalds/c/c96aec344de0de857ef3d7fba53992c7ba311e1e commit]

  • dm thin: range discard support [https://git.kernel.org/torvalds/c/34fbcf6257eb3f39a5b78a4f51b40f881b82033b commit]

7. Cryptography

• Add jitterentropy RNG. The CPU Jitter RNG provides a source of good entropy by collecting CPU executing time jitter. The entropy in the CPU execution time jitter is magnified by the CPU Jitter Random Number Generator [https://git.kernel.org/torvalds/c/bb5530e4082446aac3a3d69780cd4dbfa4520013 commit]

• drbg: use Jitter RNG to obtain seed [https://git.kernel.org/torvalds/c/b8ec5ba42c4a3854e27c44e697d9b4f0b84b32bb commit]

• rng: Make DRBG the default crypto api RNG [https://git.kernel.org/torvalds/c/401e4238f35c7a21d32bc27370d4d045f7019c20 commit]

• New chacha20 cipher. ChaCha20 is a 256-bit high-speed stream cipher [http://cr.yp.to/chacha/chacha-20080128.pdf designed by Daniel J.Bernstein] and further specified in RFC7539 for use in IETF protocols [https://git.kernel.org/torvalds/c/c08d0e647305c3f8f640010a56c9e4bafb9488d3 commit]

• Add Poly1305 authenticator algorithm. Poly1305 is an authenticator algorithm designed by Daniel J. Bernstein, it is used for the ChaCha20-Poly1305 AEAD, specified in RFC7539 for use in IETF protocols [https://git.kernel.org/torvalds/c/71ebc4d1b27d345342bdcb32a29c8cc3da8c6654 commit], [https://git.kernel.org/torvalds/c/4db4ad26096c4c1e579f9a957ca7752fe02bf7b4 commit], [https://git.kernel.org/torvalds/c/f979e014c50ce3f7467f133898dbea2243247a91 commit]

• rsa: add a new rsa generic implementation [https://git.kernel.org/torvalds/c/cfc2bb32b31371d6bffc6bf2da3548f20ad48c83 commit]

• Added support for SEC1 hardware to talitos [https://git.kernel.org/torvalds/c/21590888490ce2a46ff4703b1503f562f4a59571 commit], [https://git.kernel.org/torvalds/c/0635b7db143195281c5a29d272bb836be58af1d4 commit], [https://git.kernel.org/torvalds/c/2d02905ebd22c0271a25e424ab209c8b7067be67 commit], [https://git.kernel.org/torvalds/c/dd3c0987f5426d2df4a0c92de82dac65874bb9a4 commit], [https://git.kernel.org/torvalds/c/7d607c6a71f7a4905831fc2b1636e080533ab2db commit], [https://git.kernel.org/torvalds/c/5b841a65dcae3ac76dc34e56c948c629de48c1a3 commit], [https://git.kernel.org/torvalds/c/90490752eb03ddc1015233034ec26816f0ea0de3 commit], [https://git.kernel.org/torvalds/c/922f9dc8d36651abea51c4f2ff9c08ba4db692ff commit], [https://git.kernel.org/torvalds/c/6f65f6ac5fb36a90ebf9a8d57cc4076b82d5009e commit], [https://git.kernel.org/torvalds/c/04a34d4680e75e9be63204b3a7b51a6abe3ce35a commit]

• echainiv: Add Encrypted Chain IV Generator, which generates an IV based on the encryption of a sequence number xored with a salt. This is the default algorithm for CBC [https://git.kernel.org/torvalds/c/a10f554fa7e09ad236cfa0bdabaf6549c0b073a4 commit]

• seqiv: Add a new IV generator seqniv which is identical to seqiv except that it skips the IV when authenticating. This is intended to be used by algorithms such as rfc4106 that does the IV authentication implicitly [https://git.kernel.org/torvalds/c/3c08fee7b5ce471a7114478ac8c6e546787bd8c2 commit]

8. Security

• selinux: enable genfscon labeling for sysfs and pstore files [https://git.kernel.org/torvalds/c/8e01472078763ebc1eaea089a1adab75dd982ccd commit]

• selinux: enable per-file labeling for debugfs files. [https://git.kernel.org/torvalds/c/134509d54e4e98888be2697a92cb4b48957b792b commit]

• Smack: allow multiple labels in onlycap [https://git.kernel.org/torvalds/c/c0d77c884461fc0dec0411e49797dc3f3651c31b commit]

9. Tracing and perf tool

• BPF

  • BPF based latency tracing [https://git.kernel.org/torvalds/c/0fb1170ee68a6aa14eca0666e02c4b62cbf1251d commit]

  • Allow BPF programs access skb->skb_iif and skb->dev->ifindex fields [https://git.kernel.org/torvalds/c/37e82c2f974b72c9ab49c787ef7b5bb1aec12768 commit]

  • Allow bpf programs to tail-call other bpf programs [https://git.kernel.org/torvalds/c/04fd61ab36ec065e194ab5e74ae34a5240d992bb commit]

  • Allow programs to write to certain skb fields [https://git.kernel.org/torvalds/c/d691f9e8d4405c334aa10d556e73c8bf44cb0e01 commit]

  • Disallow bpf tc programs access current->pid,uid [https://git.kernel.org/torvalds/c/89d256bb69f2596c3a31ac51466eac9e1791c388 commit]

10. Virtualization

• KVM

  • Implement multiple address spaces [https://git.kernel.org/torvalds/c/f481b069e674378758c73761827e83ab05c46b52 commit]

• Hyper-V

  • file copy service: full handshake support [https://git.kernel.org/torvalds/c/a4d1ee5b0255a135fead1d62a7fc7e6fe718b66e commit]

  • vmbus: Implement NUMA aware CPU affinity for channels [https://git.kernel.org/torvalds/c/1f656ff3fdddc2f59649cc84b633b799908f1f7b commit]

  • vmbus: Implement the protocol for tearing down vmbus state [https://git.kernel.org/torvalds/c/2db84eff127e3f4b3635edc589cd6a56db8755a3 commit]

  • vss: full handshake support [https://git.kernel.org/torvalds/c/cd8dc0548511efff7a97d978f989ce67a883f9a5 commit]

  • Tools: kvp: use misc char device to communicate with kernel [https://git.kernel.org/torvalds/c/8ddca8088586303cfe3db4209a4682f7a4cf7d2d commit], vss: use misc char device to communicate with kernel [https://git.kernel.org/torvalds/c/f5722b9bd418e29b7429bd9a43bd100599b26d4f commit]

11. Networking

• bonding

  • Add netlink support for sys prio, actor sys mac, and port key, until now they were only exported via bond's proc entry [https://git.kernel.org/torvalds/c/171a42c38c6e1a5a076d6276e94e55a0b5b7868c commit]

  • Allow userspace to set actors' macaddr in an AD-system. [https://git.kernel.org/torvalds/c/74514957552edd4661a4608618121f3c71d4e891 commit]

  • Allow userspace to set actors' system_priority in AD system [https://git.kernel.org/torvalds/c/6791e4661c4bd3e9f193a84247f2c389578a4336 commit]

  • Implement user key part of port_key in an AD system. [https://git.kernel.org/torvalds/c/d22a5fc0c32edcf5c3bb973ee8c9a2606ba500a8 commit]

• bridge: allow setting hash_max + multicast_router if interface is down [https://git.kernel.org/torvalds/c/6ae4ae8e512bd229f806c22f8a2cd751e4f987c2 commit]

• Adds an optional ce_threshold to codel & fq_codel qdiscs, so that DCTCP can have feedback from queuing in the host [https://git.kernel.org/torvalds/c/80ba92fa1a92dea128283f69f55b02242e213650 commit]

• wireless

  • cfg80211: allow the plink state blocking for user managed mesh [https://git.kernel.org/torvalds/c/4292504044a4fd4c5d9155dcb5c7b09ed6cbf611 commit]

• Bluetooth

  • hci_core/mgmt: Introduce multi-adv list [https://git.kernel.org/torvalds/c/d2609b345ebf0547015a78588c4d7ad68c9ccf26 commit]

  • mgmt: program multi-adv on power on [https://git.kernel.org/torvalds/c/320b3bf7027b89821030e5e7c5fbd1f6aecb4af0 commit]

• NFC: netlink: Implement vendor-specific command support [https://git.kernel.org/torvalds/c/9e58095f9660f88d6a2febe87d5073a6b2e9c399 commit]

12. List of merges

13. Other news sites

• LWN merge window [https://lwn.net/Articles/648995/ part 1], [https://lwn.net/Articles/649652/ part 2], [https://lwn.net/Articles/650299/ part 3]