Documentation/feature-removal-schedule.txt

   1 The following is a list of files and features that are going to be
   2 removed in the kernel source tree.  Every entry should contain what
   3 exactly is going away, why it is happening, and who is going to be doing
   4 the work.  When the feature is removed from the kernel, it should also
   5 be removed from this file.
   6
   7 ---------------------------
   8
   9 What:   PRISM54
  10 When:   2.6.34
  11
  12 Why:    prism54 FullMAC PCI / Cardbus devices used to be supported only by the
  13         prism54 wireless driver. After Intersil stopped selling these
  14         devices in preference for the newer more flexible SoftMAC devices
  15         a SoftMAC device driver was required and prism54 did not support
  16         them. The p54pci driver now exists and has been present in the kernel for
  17         a while. This driver supports both SoftMAC devices and FullMAC devices.
  18         The main difference between these devices was the amount of memory which
  19         could be used for the firmware. The SoftMAC devices support a smaller
  20         amount of memory. Because of this the SoftMAC firmware fits into FullMAC
  21         devices's memory. p54pci supports not only PCI / Cardbus but also USB
  22         and SPI. Since p54pci supports all devices prism54 supports
  23         you will have a conflict. I'm not quite sure how distributions are
  24         handling this conflict right now. prism54 was kept around due to
  25         claims users may experience issues when using the SoftMAC driver.
  26         Time has passed users have not reported issues. If you use prism54
  27         and for whatever reason you cannot use p54pci please let us know!
  28         E-mail us at: linux-wireless@vger.kernel.org
  29
  30         For more information see the p54 wiki page:
  31
  32         http://wireless.kernel.org/en/users/Drivers/p54
  33
  34 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  35
  36 ---------------------------
  37
  38 What:   AR9170USB
  39 When:   2.6.40
  40
  41 Why:    This driver is deprecated and the firmware is no longer
  42         maintained. The replacement driver "carl9170" has been
  43         around for a while, so the devices are still supported.
  44
  45 Who:    Christian Lamparter <chunkeey@googlemail.com>
  46
  47 ---------------------------
  48
  49 What:   IRQF_SAMPLE_RANDOM
  50 Check:  IRQF_SAMPLE_RANDOM
  51 When:   July 2009
  52
  53 Why:    Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
  54         sources in the kernel's current entropy model. To resolve this, every
  55         input point to the kernel's entropy pool needs to better document the
  56         type of entropy source it actually is. This will be replaced with
  57         additional add_*_randomness functions in drivers/char/random.c
  58
  59 Who:    Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
  60
  61 ---------------------------
  62
  63 What:   Deprecated snapshot ioctls
  64 When:   2.6.36
  65
  66 Why:    The ioctls in kernel/power/user.c were marked as deprecated long time
  67         ago. Now they notify users about that so that they need to replace
  68         their userspace. After some more time, remove them completely.
  69
  70 Who:    Jiri Slaby <jirislaby@gmail.com>
  71
  72 ---------------------------
  73
  74 What:   The ieee80211_regdom module parameter
  75 When:   March 2010 / desktop catchup
  76
  77 Why:    This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
  78         and currently serves as an option for users to define an
  79         ISO / IEC 3166 alpha2 code for the country they are currently
  80         present in. Although there are userspace API replacements for this
  81         through nl80211 distributions haven't yet caught up with implementing
  82         decent alternatives through standard GUIs. Although available as an
  83         option through iw or wpa_supplicant its just a matter of time before
  84         distributions pick up good GUI options for this. The ideal solution
  85         would actually consist of intelligent designs which would do this for
  86         the user automatically even when travelling through different countries.
  87         Until then we leave this module parameter as a compromise.
  88
  89         When userspace improves with reasonable widely-available alternatives for
  90         this we will no longer need this module parameter. This entry hopes that
  91         by the super-futuristically looking date of "March 2010" we will have
  92         such replacements widely available.
  93
  94 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  95
  96 ---------------------------
  97
  98 What:   dev->power.power_state
  99 When:   July 2007
 100 Why:    Broken design for runtime control over driver power states, confusing
 101         driver-internal runtime power management with:  mechanisms to support
 102         system-wide sleep state transitions; event codes that distinguish
 103         different phases of swsusp "sleep" transitions; and userspace policy
 104         inputs.  This framework was never widely used, and most attempts to
 105         use it were broken.  Drivers should instead be exposing domain-specific
 106         interfaces either to kernel or to userspace.
 107 Who:    Pavel Machek <pavel@ucw.cz>
 108
 109 ---------------------------
 110
 111 What:   Video4Linux obsolete drivers using V4L1 API
 112 When:   kernel 2.6.39
 113 Files:  drivers/staging/se401/* drivers/staging/usbvideo/*
 114 Check:  drivers/staging/se401/se401.c drivers/staging/usbvideo/usbvideo.c
 115 Why:    There are some drivers still using V4L1 API, despite all efforts we've done
 116         to migrate. Those drivers are for obsolete hardware that the old maintainer
 117         didn't care (or not have the hardware anymore), and that no other developer
 118         could find any hardware to buy. They probably have no practical usage today,
 119         and people with such old hardware could probably keep using an older version
 120         of the kernel. Those drivers will be moved to staging on 2.6.38 and, if nobody
 121         cares enough to port and test them with V4L2 API, they'll be removed on 2.6.39.
 122 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
 123
 124 ---------------------------
 125
 126 What:   Video4Linux: Remove obsolete ioctl's
 127 When:   kernel 2.6.39
 128 Files:  include/media/videodev2.h
 129 Why:    Some ioctl's were defined wrong on 2.6.2 and 2.6.6, using the wrong
 130         type of R/W arguments. They were fixed, but the old ioctl names are
 131         still there, maintained to avoid breaking binary compatibility:
 132           #define VIDIOC_OVERLAY_OLD    _IOWR('V', 14, int)
 133           #define VIDIOC_S_PARM_OLD     _IOW('V', 22, struct v4l2_streamparm)
 134           #define VIDIOC_S_CTRL_OLD     _IOW('V', 28, struct v4l2_control)
 135           #define VIDIOC_G_AUDIO_OLD    _IOWR('V', 33, struct v4l2_audio)
 136           #define VIDIOC_G_AUDOUT_OLD   _IOWR('V', 49, struct v4l2_audioout)
 137           #define VIDIOC_CROPCAP_OLD    _IOR('V', 58, struct v4l2_cropcap)
 138         There's no sense on preserving those forever, as it is very doubtful
 139         that someone would try to use a such old binary with a modern kernel.
 140         Removing them will allow us to remove some magic done at the V4L ioctl
 141         handler.
 142
 143 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
 144
 145 ---------------------------
 146
 147 What:   sys_sysctl
 148 When:   September 2010
 149 Option: CONFIG_SYSCTL_SYSCALL
 150 Why:    The same information is available in a more convenient from
 151         /proc/sys, and none of the sysctl variables appear to be
 152         important performance wise.
 153
 154         Binary sysctls are a long standing source of subtle kernel
 155         bugs and security issues.
 156
 157         When I looked several months ago all I could find after
 158         searching several distributions were 5 user space programs and
 159         glibc (which falls back to /proc/sys) using this syscall.
 160
 161         The man page for sysctl(2) documents it as unusable for user
 162         space programs.
 163
 164         sysctl(2) is not generally ABI compatible to a 32bit user
 165         space application on a 64bit and a 32bit kernel.
 166
 167         For the last several months the policy has been no new binary
 168         sysctls and no one has put forward an argument to use them.
 169
 170         Binary sysctls issues seem to keep happening appearing so
 171         properly deprecating them (with a warning to user space) and a
 172         2 year grace warning period will mean eventually we can kill
 173         them and end the pain.
 174
 175         In the mean time individual binary sysctls can be dealt with
 176         in a piecewise fashion.
 177
 178 Who:    Eric Biederman <ebiederm@xmission.com>
 179
 180 ---------------------------
 181
 182 What:   /proc/<pid>/oom_adj
 183 When:   August 2012
 184 Why:    /proc/<pid>/oom_adj allows userspace to influence the oom killer's
 185         badness heuristic used to determine which task to kill when the kernel
 186         is out of memory.
 187
 188         The badness heuristic has since been rewritten since the introduction of
 189         this tunable such that its meaning is deprecated.  The value was
 190         implemented as a bitshift on a score generated by the badness()
 191         function that did not have any precise units of measure.  With the
 192         rewrite, the score is given as a proportion of available memory to the
 193         task allocating pages, so using a bitshift which grows the score
 194         exponentially is, thus, impossible to tune with fine granularity.
 195
 196         A much more powerful interface, /proc/<pid>/oom_score_adj, was
 197         introduced with the oom killer rewrite that allows users to increase or
 198         decrease the badness() score linearly.  This interface will replace
 199         /proc/<pid>/oom_adj.
 200
 201         A warning will be emitted to the kernel log if an application uses this
 202         deprecated interface.  After it is printed once, future warnings will be
 203         suppressed until the kernel is rebooted.
 204
 205 ---------------------------
 206
 207 What:   CS5535/CS5536 obsolete GPIO driver
 208 When:   June 2011
 209 Files:  drivers/staging/cs5535_gpio/*
 210 Check:  drivers/staging/cs5535_gpio/cs5535_gpio.c
 211 Why:    A newer driver replaces this; it is drivers/gpio/cs5535-gpio.c, and
 212         integrates with the Linux GPIO subsystem.  The old driver has been
 213         moved to staging, and will be removed altogether around 2.6.40.
 214         Please test the new driver, and ensure that the functionality you
 215         need and any bugfixes from the old driver are available in the new
 216         one.
 217 Who:    Andres Salomon <dilinger@queued.net>
 218
 219 --------------------------
 220
 221 What:   remove EXPORT_SYMBOL(kernel_thread)
 222 When:   August 2006
 223 Files:  arch/*/kernel/*_ksyms.c
 224 Check:  kernel_thread
 225 Why:    kernel_thread is a low-level implementation detail.  Drivers should
 226         use the <linux/kthread.h> API instead which shields them from
 227         implementation details and provides a higherlevel interface that
 228         prevents bugs and code duplication
 229 Who:    Christoph Hellwig <hch@lst.de>
 230
 231 ---------------------------
 232
 233 What:   Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
 234         (temporary transition config option provided until then)
 235         The transition config option will also be removed at the same time.
 236 When:   before 2.6.19
 237 Why:    Unused symbols are both increasing the size of the kernel binary
 238         and are often a sign of "wrong API"
 239 Who:    Arjan van de Ven <arjan@linux.intel.com>
 240
 241 ---------------------------
 242
 243 What:   PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 244 When:   October 2008
 245 Why:    The stacking of class devices makes these values misleading and
 246         inconsistent.
 247         Class devices should not carry any of these properties, and bus
 248         devices have SUBSYTEM and DRIVER as a replacement.
 249 Who:    Kay Sievers <kay.sievers@suse.de>
 250
 251 ---------------------------
 252
 253 What:   ACPI procfs interface
 254 When:   July 2008
 255 Why:    ACPI sysfs conversion should be finished by January 2008.
 256         ACPI procfs interface will be removed in July 2008 so that
 257         there is enough time for the user space to catch up.
 258 Who:    Zhang Rui <rui.zhang@intel.com>
 259
 260 ---------------------------
 261
 262 What:   CONFIG_ACPI_PROCFS_POWER
 263 When:   2.6.39
 264 Why:    sysfs I/F for ACPI power devices, including AC and Battery,
 265         has been working in upstream kenrel since 2.6.24, Sep 2007.
 266         In 2.6.37, we make the sysfs I/F always built in and this option
 267         disabled by default.
 268         Remove this option and the ACPI power procfs interface in 2.6.39.
 269 Who:    Zhang Rui <rui.zhang@intel.com>
 270
 271 ---------------------------
 272
 273 What:   /proc/acpi/event
 274 When:   February 2008
 275 Why:    /proc/acpi/event has been replaced by events via the input layer
 276         and netlink since 2.6.23.
 277 Who:    Len Brown <len.brown@intel.com>
 278
 279 ---------------------------
 280
 281 What:   i386/x86_64 bzImage symlinks
 282 When:   April 2010
 283
 284 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 285         location so not yet updated user space tools, e.g. package
 286         scripts, do not break.
 287 Who:    Thomas Gleixner <tglx@linutronix.de>
 288
 289 ---------------------------
 290
 291 What:   GPIO autorequest on gpio_direction_{input,output}() in gpiolib
 292 When:   February 2010
 293 Why:    All callers should use explicit gpio_request()/gpio_free().
 294         The autorequest mechanism in gpiolib was provided mostly as a
 295         migration aid for legacy GPIO interfaces (for SOC based GPIOs).
 296         Those users have now largely migrated.  Platforms implementing
 297         the GPIO interfaces without using gpiolib will see no changes.
 298 Who:    David Brownell <dbrownell@users.sourceforge.net>
 299 ---------------------------
 300
 301 What:   b43 support for firmware revision < 410
 302 When:   The schedule was July 2008, but it was decided that we are going to keep the
 303         code as long as there are no major maintanance headaches.
 304         So it _could_ be removed _any_ time now, if it conflicts with something new.
 305 Why:    The support code for the old firmware hurts code readability/maintainability
 306         and slightly hurts runtime performance. Bugfixes for the old firmware
 307         are not provided by Broadcom anymore.
 308 Who:    Michael Buesch <mb@bu3sch.de>
 309
 310 ---------------------------
 311
 312 What:   /sys/o2cb symlink
 313 When:   January 2010
 314 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 315         exists as a symlink for backwards compatibility for old versions of
 316         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 317         which know to look in /sys/fs/o2cb.
 318 Who:    ocfs2-devel@oss.oracle.com
 319
 320 ---------------------------
 321
 322 What:   Ability for non root users to shm_get hugetlb pages based on mlock
 323         resource limits
 324 When:   2.6.31
 325 Why:    Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
 326         have CAP_IPC_LOCK to be able to allocate shm segments backed by
 327         huge pages.  The mlock based rlimit check to allow shm hugetlb is
 328         inconsistent with mmap based allocations.  Hence it is being
 329         deprecated.
 330 Who:    Ravikiran Thirumalai <kiran@scalex86.org>
 331
 332 ---------------------------
 333
 334 What:   CONFIG_THERMAL_HWMON
 335 When:   January 2009
 336 Why:    This option was introduced just to allow older lm-sensors userspace
 337         to keep working over the upgrade to 2.6.26. At the scheduled time of
 338         removal fixed lm-sensors (2.x or 3.x) should be readily available.
 339 Who:    Rene Herman <rene.herman@gmail.com>
 340
 341 ---------------------------
 342
 343 What:   Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 344         (in net/core/net-sysfs.c)
 345 When:   After the only user (hal) has seen a release with the patches
 346         for enough time, probably some time in 2010.
 347 Why:    Over 1K .text/.data size reduction, data is available in other
 348         ways (ioctls)
 349 Who:    Johannes Berg <johannes@sipsolutions.net>
 350
 351 ---------------------------
 352
 353 What:   sysfs ui for changing p4-clockmod parameters
 354 When:   September 2009
 355 Why:    See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
 356         e088e4c9cdb618675874becb91b2fd581ee707e6.
 357         Removal is subject to fixing any remaining bugs in ACPI which may
 358         cause the thermal throttling not to happen at the right time.
 359 Who:    Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
 360
 361 -----------------------------
 362
 363 What:   fakephp and associated sysfs files in /sys/bus/pci/slots/
 364 When:   2011
 365 Why:    In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
 366         represent a machine's physical PCI slots. The change in semantics
 367         had userspace implications, as the hotplug core no longer allowed
 368         drivers to create multiple sysfs files per physical slot (required
 369         for multi-function devices, e.g.). fakephp was seen as a developer's
 370         tool only, and its interface changed. Too late, we learned that
 371         there were some users of the fakephp interface.
 372
 373         In 2.6.30, the original fakephp interface was restored. At the same
 374         time, the PCI core gained the ability that fakephp provided, namely
 375         function-level hot-remove and hot-add.
 376
 377         Since the PCI core now provides the same functionality, exposed in:
 378
 379                 /sys/bus/pci/rescan
 380                 /sys/bus/pci/devices/.../remove
 381                 /sys/bus/pci/devices/.../rescan
 382
 383         there is no functional reason to maintain fakephp as well.
 384
 385         We will keep the existing module so that 'modprobe fakephp' will
 386         present the old /sys/bus/pci/slots/... interface for compatibility,
 387         but users are urged to migrate their applications to the API above.
 388
 389         After a reasonable transition period, we will remove the legacy
 390         fakephp interface.
 391 Who:    Alex Chiang <achiang@hp.com>
 392
 393 ---------------------------
 394
 395 What:   CONFIG_RFKILL_INPUT
 396 When:   2.6.33
 397 Why:    Should be implemented in userspace, policy daemon.
 398 Who:    Johannes Berg <johannes@sipsolutions.net>
 399
 400 ----------------------------
 401
 402 What:   sound-slot/service-* module aliases and related clutters in
 403         sound/sound_core.c
 404 When:   August 2010
 405 Why:    OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
 406         (14) and requests modules using custom sound-slot/service-*
 407         module aliases.  The only benefit of doing this is allowing
 408         use of custom module aliases which might as well be considered
 409         a bug at this point.  This preemptive claiming prevents
 410         alternative OSS implementations.
 411
 412         Till the feature is removed, the kernel will be requesting
 413         both sound-slot/service-* and the standard char-major-* module
 414         aliases and allow turning off the pre-claiming selectively via
 415         CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
 416         kernel parameter.
 417
 418         After the transition phase is complete, both the custom module
 419         aliases and switches to disable it will go away.  This removal
 420         will also allow making ALSA OSS emulation independent of
 421         sound_core.  The dependency will be broken then too.
 422 Who:    Tejun Heo <tj@kernel.org>
 423
 424 ----------------------------
 425
 426 What:   Support for lcd_switch and display_get in asus-laptop driver
 427 When:   March 2010
 428 Why:    These two features use non-standard interfaces. There are the
 429         only features that really need multiple path to guess what's
 430         the right method name on a specific laptop.
 431
 432         Removing them will allow to remove a lot of code an significantly
 433         clean the drivers.
 434
 435         This will affect the backlight code which won't be able to know
 436         if the backlight is on or off. The platform display file will also be
 437         write only (like the one in eeepc-laptop).
 438
 439         This should'nt affect a lot of user because they usually know
 440         when their display is on or off.
 441
 442 Who:    Corentin Chary <corentin.chary@gmail.com>
 443
 444 ----------------------------
 445
 446 What:   sysfs-class-rfkill state file
 447 When:   Feb 2014
 448 Files:  net/rfkill/core.c
 449 Why:    Documented as obsolete since Feb 2010. This file is limited to 3
 450         states while the rfkill drivers can have 4 states.
 451 Who:    anybody or Florian Mickler <florian@mickler.org>
 452
 453 ----------------------------
 454
 455 What:   sysfs-class-rfkill claim file
 456 When:   Feb 2012
 457 Files:  net/rfkill/core.c
 458 Why:    It is not possible to claim an rfkill driver since 2007. This is
 459         Documented as obsolete since Feb 2010.
 460 Who:    anybody or Florian Mickler <florian@mickler.org>
 461
 462 ----------------------------
 463
 464 What:   capifs
 465 When:   February 2011
 466 Files:  drivers/isdn/capi/capifs.*
 467 Why:    udev fully replaces this special file system that only contains CAPI
 468         NCCI TTY device nodes. User space (pppdcapiplugin) works without
 469         noticing the difference.
 470 Who:    Jan Kiszka <jan.kiszka@web.de>
 471
 472 ----------------------------
 473
 474 What:   KVM paravirt mmu host support
 475 When:   January 2011
 476 Why:    The paravirt mmu host support is slower than non-paravirt mmu, both
 477         on newer and older hardware.  It is already not exposed to the guest,
 478         and kept only for live migration purposes.
 479 Who:    Avi Kivity <avi@redhat.com>
 480
 481 ----------------------------
 482
 483 What:   iwlwifi 50XX module parameters
 484 When:   2.6.40
 485 Why:    The "..50" modules parameters were used to configure 5000 series and
 486         up devices; different set of module parameters also available for 4965
 487         with same functionalities. Consolidate both set into single place
 488         in drivers/net/wireless/iwlwifi/iwl-agn.c
 489
 490 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 491
 492 ----------------------------
 493
 494 What:   iwl4965 alias support
 495 When:   2.6.40
 496 Why:    Internal alias support has been present in module-init-tools for some
 497         time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
 498         with no impact.
 499
 500 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 501
 502 ---------------------------
 503
 504 What:   xt_NOTRACK
 505 Files:  net/netfilter/xt_NOTRACK.c
 506 When:   April 2011
 507 Why:    Superseded by xt_CT
 508 Who:    Netfilter developer team <netfilter-devel@vger.kernel.org>
 509
 510 ----------------------------
 511
 512 What:   IRQF_DISABLED
 513 When:   2.6.36
 514 Why:    The flag is a NOOP as we run interrupt handlers with interrupts disabled
 515 Who:    Thomas Gleixner <tglx@linutronix.de>
 516
 517 ----------------------------
 518
 519 What:   The acpi_sleep=s4_nonvs command line option
 520 When:   2.6.37
 521 Files:  arch/x86/kernel/acpi/sleep.c
 522 Why:    superseded by acpi_sleep=nonvs
 523 Who:    Rafael J. Wysocki <rjw@sisk.pl>
 524
 525 ----------------------------
 526
 527 What:   PCI DMA unmap state API
 528 When:   August 2012
 529 Why:    PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
 530         with DMA unmap state API (DMA unmap state API can be used for
 531         any bus).
 532 Who:    FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 533
 534 ----------------------------
 535
 536 What:   DMA_xxBIT_MASK macros
 537 When:   Jun 2011
 538 Why:    DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros.
 539 Who:    FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 540
 541 ----------------------------
 542
 543 What:   namespace cgroup (ns_cgroup)
 544 When:   2.6.38
 545 Why:    The ns_cgroup leads to some problems:
 546         * cgroup creation is out-of-control
 547         * cgroup name can conflict when pids are looping
 548         * it is not possible to have a single process handling
 549         a lot of namespaces without falling in a exponential creation time
 550         * we may want to create a namespace without creating a cgroup
 551
 552         The ns_cgroup is replaced by a compatibility flag 'clone_children',
 553         where a newly created cgroup will copy the parent cgroup values.
 554         The userspace has to manually create a cgroup and add a task to
 555         the 'tasks' file.
 556 Who:    Daniel Lezcano <daniel.lezcano@free.fr>
 557
 558 ----------------------------
 559
 560 What:   iwlwifi disable_hw_scan module parameters
 561 When:   2.6.40
 562 Why:    Hareware scan is the prefer method for iwlwifi devices for
 563         scanning operation. Remove software scan support for all the
 564         iwlwifi devices.
 565
 566 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 567
 568 ----------------------------
 569
 570 What:   access to nfsd auth cache through sys_nfsservctl or '.' files
 571         in the 'nfsd' filesystem.
 572 When:   2.6.40
 573 Why:    This is a legacy interface which have been replaced by a more
 574         dynamic cache.  Continuing to maintain this interface is an
 575         unnecessary burden.
 576 Who:    NeilBrown <neilb@suse.de>
 577
 578 ----------------------------
 579
 580 What:   cancel_rearming_delayed_work[queue]()
 581 When:   2.6.39
 582
 583 Why:    The functions have been superceded by cancel_delayed_work_sync()
 584         quite some time ago.  The conversion is trivial and there is no
 585         in-kernel user left.
 586 Who:    Tejun Heo <tj@kernel.org>
 587
 588 ----------------------------
 589
 590 What:   Legacy, non-standard chassis intrusion detection interface.
 591 When:   June 2011
 592 Why:    The adm9240, w83792d and w83793 hardware monitoring drivers have
 593         legacy interfaces for chassis intrusion detection. A standard
 594         interface has been added to each driver, so the legacy interface
 595         can be removed.
 596 Who:    Jean Delvare <khali@linux-fr.org>
 597
 598 ----------------------------
 599
 600 What:   xt_connlimit rev 0
 601 When:   2012
 602 Who:    Jan Engelhardt <jengelh@medozas.de>
 603 Files:  net/netfilter/xt_connlimit.c
 604
 605 ----------------------------
 606
 607 What:   noswapaccount kernel command line parameter
 608 When:   2.6.40
 609 Why:    The original implementation of memsw feature enabled by
 610         CONFIG_CGROUP_MEM_RES_CTLR_SWAP could be disabled by the noswapaccount
 611         kernel parameter (introduced in 2.6.29-rc1). Later on, this decision
 612         turned out to be not ideal because we cannot have the feature compiled
 613         in and disabled by default and let only interested to enable it
 614         (e.g. general distribution kernels might need it). Therefore we have
 615         added swapaccount[=0|1] parameter (introduced in 2.6.37) which provides
 616         the both possibilities. If we remove noswapaccount we will have
 617         less command line parameters with the same functionality and we
 618         can also cleanup the parameter handling a bit ().
 619 Who:    Michal Hocko <mhocko@suse.cz>
 620
 621 ----------------------------
 622
 623 What:   ipt_addrtype match include file
 624 When:   2012
 625 Why:    superseded by xt_addrtype
 626 Who:    Florian Westphal <fw@strlen.de>
 627 Files:  include/linux/netfilter_ipv4/ipt_addrtype.h
 628
 629 ----------------------------
 630
 631 What:   i2c_driver.attach_adapter
 632         i2c_driver.detach_adapter
 633 When:   September 2011
 634 Why:    These legacy callbacks should no longer be used as i2c-core offers
 635         a variety of preferable alternative ways to instantiate I2C devices.
 636 Who:    Jean Delvare <khali@linux-fr.org>
 637
 638 ----------------------------