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:   IRQF_SAMPLE_RANDOM
  39 Check:  IRQF_SAMPLE_RANDOM
  40 When:   July 2009
  41
  42 Why:    Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
  43         sources in the kernel's current entropy model. To resolve this, every
  44         input point to the kernel's entropy pool needs to better document the
  45         type of entropy source it actually is. This will be replaced with
  46         additional add_*_randomness functions in drivers/char/random.c
  47
  48 Who:    Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
  49
  50 ---------------------------
  51
  52 What:   Deprecated snapshot ioctls
  53 When:   2.6.36
  54
  55 Why:    The ioctls in kernel/power/user.c were marked as deprecated long time
  56         ago. Now they notify users about that so that they need to replace
  57         their userspace. After some more time, remove them completely.
  58
  59 Who:    Jiri Slaby <jirislaby@gmail.com>
  60
  61 ---------------------------
  62
  63 What:   The ieee80211_regdom module parameter
  64 When:   March 2010 / desktop catchup
  65
  66 Why:    This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
  67         and currently serves as an option for users to define an
  68         ISO / IEC 3166 alpha2 code for the country they are currently
  69         present in. Although there are userspace API replacements for this
  70         through nl80211 distributions haven't yet caught up with implementing
  71         decent alternatives through standard GUIs. Although available as an
  72         option through iw or wpa_supplicant its just a matter of time before
  73         distributions pick up good GUI options for this. The ideal solution
  74         would actually consist of intelligent designs which would do this for
  75         the user automatically even when travelling through different countries.
  76         Until then we leave this module parameter as a compromise.
  77
  78         When userspace improves with reasonable widely-available alternatives for
  79         this we will no longer need this module parameter. This entry hopes that
  80         by the super-futuristically looking date of "March 2010" we will have
  81         such replacements widely available.
  82
  83 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  84
  85 ---------------------------
  86
  87 What:   dev->power.power_state
  88 When:   July 2007
  89 Why:    Broken design for runtime control over driver power states, confusing
  90         driver-internal runtime power management with:  mechanisms to support
  91         system-wide sleep state transitions; event codes that distinguish
  92         different phases of swsusp "sleep" transitions; and userspace policy
  93         inputs.  This framework was never widely used, and most attempts to
  94         use it were broken.  Drivers should instead be exposing domain-specific
  95         interfaces either to kernel or to userspace.
  96 Who:    Pavel Machek <pavel@ucw.cz>
  97
  98 ---------------------------
  99
 100 What:   Video4Linux obsolete drivers using V4L1 API
 101 When:   kernel 2.6.39
 102 Files:  drivers/staging/se401/* drivers/staging/usbvideo/*
 103 Check:  drivers/staging/se401/se401.c drivers/staging/usbvideo/usbvideo.c
 104 Why:    There are some drivers still using V4L1 API, despite all efforts we've done
 105         to migrate. Those drivers are for obsolete hardware that the old maintainer
 106         didn't care (or not have the hardware anymore), and that no other developer
 107         could find any hardware to buy. They probably have no practical usage today,
 108         and people with such old hardware could probably keep using an older version
 109         of the kernel. Those drivers will be moved to staging on 2.6.38 and, if nobody
 110         cares enough to port and test them with V4L2 API, they'll be removed on 2.6.39.
 111 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
 112
 113 ---------------------------
 114
 115 What:   Video4Linux: Remove obsolete ioctl's
 116 When:   kernel 2.6.39
 117 Files:  include/media/videodev2.h
 118 Why:    Some ioctl's were defined wrong on 2.6.2 and 2.6.6, using the wrong
 119         type of R/W arguments. They were fixed, but the old ioctl names are
 120         still there, maintained to avoid breaking binary compatibility:
 121           #define VIDIOC_OVERLAY_OLD    _IOWR('V', 14, int)
 122           #define VIDIOC_S_PARM_OLD     _IOW('V', 22, struct v4l2_streamparm)
 123           #define VIDIOC_S_CTRL_OLD     _IOW('V', 28, struct v4l2_control)
 124           #define VIDIOC_G_AUDIO_OLD    _IOWR('V', 33, struct v4l2_audio)
 125           #define VIDIOC_G_AUDOUT_OLD   _IOWR('V', 49, struct v4l2_audioout)
 126           #define VIDIOC_CROPCAP_OLD    _IOR('V', 58, struct v4l2_cropcap)
 127         There's no sense on preserving those forever, as it is very doubtful
 128         that someone would try to use a such old binary with a modern kernel.
 129         Removing them will allow us to remove some magic done at the V4L ioctl
 130         handler.
 131
 132 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
 133
 134 ---------------------------
 135
 136 What:   sys_sysctl
 137 When:   September 2010
 138 Option: CONFIG_SYSCTL_SYSCALL
 139 Why:    The same information is available in a more convenient from
 140         /proc/sys, and none of the sysctl variables appear to be
 141         important performance wise.
 142
 143         Binary sysctls are a long standing source of subtle kernel
 144         bugs and security issues.
 145
 146         When I looked several months ago all I could find after
 147         searching several distributions were 5 user space programs and
 148         glibc (which falls back to /proc/sys) using this syscall.
 149
 150         The man page for sysctl(2) documents it as unusable for user
 151         space programs.
 152
 153         sysctl(2) is not generally ABI compatible to a 32bit user
 154         space application on a 64bit and a 32bit kernel.
 155
 156         For the last several months the policy has been no new binary
 157         sysctls and no one has put forward an argument to use them.
 158
 159         Binary sysctls issues seem to keep happening appearing so
 160         properly deprecating them (with a warning to user space) and a
 161         2 year grace warning period will mean eventually we can kill
 162         them and end the pain.
 163
 164         In the mean time individual binary sysctls can be dealt with
 165         in a piecewise fashion.
 166
 167 Who:    Eric Biederman <ebiederm@xmission.com>
 168
 169 ---------------------------
 170
 171 What:   /proc/<pid>/oom_adj
 172 When:   August 2012
 173 Why:    /proc/<pid>/oom_adj allows userspace to influence the oom killer's
 174         badness heuristic used to determine which task to kill when the kernel
 175         is out of memory.
 176
 177         The badness heuristic has since been rewritten since the introduction of
 178         this tunable such that its meaning is deprecated.  The value was
 179         implemented as a bitshift on a score generated by the badness()
 180         function that did not have any precise units of measure.  With the
 181         rewrite, the score is given as a proportion of available memory to the
 182         task allocating pages, so using a bitshift which grows the score
 183         exponentially is, thus, impossible to tune with fine granularity.
 184
 185         A much more powerful interface, /proc/<pid>/oom_score_adj, was
 186         introduced with the oom killer rewrite that allows users to increase or
 187         decrease the badness() score linearly.  This interface will replace
 188         /proc/<pid>/oom_adj.
 189
 190         A warning will be emitted to the kernel log if an application uses this
 191         deprecated interface.  After it is printed once, future warnings will be
 192         suppressed until the kernel is rebooted.
 193
 194 ---------------------------
 195
 196 What:   CS5535/CS5536 obsolete GPIO driver
 197 When:   June 2011
 198 Files:  drivers/staging/cs5535_gpio/*
 199 Check:  drivers/staging/cs5535_gpio/cs5535_gpio.c
 200 Why:    A newer driver replaces this; it is drivers/gpio/cs5535-gpio.c, and
 201         integrates with the Linux GPIO subsystem.  The old driver has been
 202         moved to staging, and will be removed altogether around 2.6.40.
 203         Please test the new driver, and ensure that the functionality you
 204         need and any bugfixes from the old driver are available in the new
 205         one.
 206 Who:    Andres Salomon <dilinger@queued.net>
 207
 208 --------------------------
 209
 210 What:   remove EXPORT_SYMBOL(kernel_thread)
 211 When:   August 2006
 212 Files:  arch/*/kernel/*_ksyms.c
 213 Check:  kernel_thread
 214 Why:    kernel_thread is a low-level implementation detail.  Drivers should
 215         use the <linux/kthread.h> API instead which shields them from
 216         implementation details and provides a higherlevel interface that
 217         prevents bugs and code duplication
 218 Who:    Christoph Hellwig <hch@lst.de>
 219
 220 ---------------------------
 221
 222 What:   Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
 223         (temporary transition config option provided until then)
 224         The transition config option will also be removed at the same time.
 225 When:   before 2.6.19
 226 Why:    Unused symbols are both increasing the size of the kernel binary
 227         and are often a sign of "wrong API"
 228 Who:    Arjan van de Ven <arjan@linux.intel.com>
 229
 230 ---------------------------
 231
 232 What:   PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 233 When:   October 2008
 234 Why:    The stacking of class devices makes these values misleading and
 235         inconsistent.
 236         Class devices should not carry any of these properties, and bus
 237         devices have SUBSYTEM and DRIVER as a replacement.
 238 Who:    Kay Sievers <kay.sievers@suse.de>
 239
 240 ---------------------------
 241
 242 What:   ACPI procfs interface
 243 When:   July 2008
 244 Why:    ACPI sysfs conversion should be finished by January 2008.
 245         ACPI procfs interface will be removed in July 2008 so that
 246         there is enough time for the user space to catch up.
 247 Who:    Zhang Rui <rui.zhang@intel.com>
 248
 249 ---------------------------
 250
 251 What:   CONFIG_ACPI_PROCFS_POWER
 252 When:   2.6.39
 253 Why:    sysfs I/F for ACPI power devices, including AC and Battery,
 254         has been working in upstream kenrel since 2.6.24, Sep 2007.
 255         In 2.6.37, we make the sysfs I/F always built in and this option
 256         disabled by default.
 257         Remove this option and the ACPI power procfs interface in 2.6.39.
 258 Who:    Zhang Rui <rui.zhang@intel.com>
 259
 260 ---------------------------
 261
 262 What:   /proc/acpi/button
 263 When:   August 2007
 264 Why:    /proc/acpi/button has been replaced by events to the input layer
 265         since 2.6.20.
 266 Who:    Len Brown <len.brown@intel.com>
 267
 268 ---------------------------
 269
 270 What:   /proc/acpi/event
 271 When:   February 2008
 272 Why:    /proc/acpi/event has been replaced by events via the input layer
 273         and netlink since 2.6.23.
 274 Who:    Len Brown <len.brown@intel.com>
 275
 276 ---------------------------
 277
 278 What:   i386/x86_64 bzImage symlinks
 279 When:   April 2010
 280
 281 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 282         location so not yet updated user space tools, e.g. package
 283         scripts, do not break.
 284 Who:    Thomas Gleixner <tglx@linutronix.de>
 285
 286 ---------------------------
 287
 288 What:   GPIO autorequest on gpio_direction_{input,output}() in gpiolib
 289 When:   February 2010
 290 Why:    All callers should use explicit gpio_request()/gpio_free().
 291         The autorequest mechanism in gpiolib was provided mostly as a
 292         migration aid for legacy GPIO interfaces (for SOC based GPIOs).
 293         Those users have now largely migrated.  Platforms implementing
 294         the GPIO interfaces without using gpiolib will see no changes.
 295 Who:    David Brownell <dbrownell@users.sourceforge.net>
 296 ---------------------------
 297
 298 What:   b43 support for firmware revision < 410
 299 When:   The schedule was July 2008, but it was decided that we are going to keep the
 300         code as long as there are no major maintanance headaches.
 301         So it _could_ be removed _any_ time now, if it conflicts with something new.
 302 Why:    The support code for the old firmware hurts code readability/maintainability
 303         and slightly hurts runtime performance. Bugfixes for the old firmware
 304         are not provided by Broadcom anymore.
 305 Who:    Michael Buesch <mb@bu3sch.de>
 306
 307 ---------------------------
 308
 309 What:   /sys/o2cb symlink
 310 When:   January 2010
 311 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 312         exists as a symlink for backwards compatibility for old versions of
 313         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 314         which know to look in /sys/fs/o2cb.
 315 Who:    ocfs2-devel@oss.oracle.com
 316
 317 ---------------------------
 318
 319 What:   Ability for non root users to shm_get hugetlb pages based on mlock
 320         resource limits
 321 When:   2.6.31
 322 Why:    Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
 323         have CAP_IPC_LOCK to be able to allocate shm segments backed by
 324         huge pages.  The mlock based rlimit check to allow shm hugetlb is
 325         inconsistent with mmap based allocations.  Hence it is being
 326         deprecated.
 327 Who:    Ravikiran Thirumalai <kiran@scalex86.org>
 328
 329 ---------------------------
 330
 331 What:   CONFIG_THERMAL_HWMON
 332 When:   January 2009
 333 Why:    This option was introduced just to allow older lm-sensors userspace
 334         to keep working over the upgrade to 2.6.26. At the scheduled time of
 335         removal fixed lm-sensors (2.x or 3.x) should be readily available.
 336 Who:    Rene Herman <rene.herman@gmail.com>
 337
 338 ---------------------------
 339
 340 What:   Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 341         (in net/core/net-sysfs.c)
 342 When:   After the only user (hal) has seen a release with the patches
 343         for enough time, probably some time in 2010.
 344 Why:    Over 1K .text/.data size reduction, data is available in other
 345         ways (ioctls)
 346 Who:    Johannes Berg <johannes@sipsolutions.net>
 347
 348 ---------------------------
 349
 350 What:   sysfs ui for changing p4-clockmod parameters
 351 When:   September 2009
 352 Why:    See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
 353         e088e4c9cdb618675874becb91b2fd581ee707e6.
 354         Removal is subject to fixing any remaining bugs in ACPI which may
 355         cause the thermal throttling not to happen at the right time.
 356 Who:    Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
 357
 358 -----------------------------
 359
 360 What:   fakephp and associated sysfs files in /sys/bus/pci/slots/
 361 When:   2011
 362 Why:    In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
 363         represent a machine's physical PCI slots. The change in semantics
 364         had userspace implications, as the hotplug core no longer allowed
 365         drivers to create multiple sysfs files per physical slot (required
 366         for multi-function devices, e.g.). fakephp was seen as a developer's
 367         tool only, and its interface changed. Too late, we learned that
 368         there were some users of the fakephp interface.
 369
 370         In 2.6.30, the original fakephp interface was restored. At the same
 371         time, the PCI core gained the ability that fakephp provided, namely
 372         function-level hot-remove and hot-add.
 373
 374         Since the PCI core now provides the same functionality, exposed in:
 375
 376                 /sys/bus/pci/rescan
 377                 /sys/bus/pci/devices/.../remove
 378                 /sys/bus/pci/devices/.../rescan
 379
 380         there is no functional reason to maintain fakephp as well.
 381
 382         We will keep the existing module so that 'modprobe fakephp' will
 383         present the old /sys/bus/pci/slots/... interface for compatibility,
 384         but users are urged to migrate their applications to the API above.
 385
 386         After a reasonable transition period, we will remove the legacy
 387         fakephp interface.
 388 Who:    Alex Chiang <achiang@hp.com>
 389
 390 ---------------------------
 391
 392 What:   CONFIG_RFKILL_INPUT
 393 When:   2.6.33
 394 Why:    Should be implemented in userspace, policy daemon.
 395 Who:    Johannes Berg <johannes@sipsolutions.net>
 396
 397 ----------------------------
 398
 399 What:   sound-slot/service-* module aliases and related clutters in
 400         sound/sound_core.c
 401 When:   August 2010
 402 Why:    OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
 403         (14) and requests modules using custom sound-slot/service-*
 404         module aliases.  The only benefit of doing this is allowing
 405         use of custom module aliases which might as well be considered
 406         a bug at this point.  This preemptive claiming prevents
 407         alternative OSS implementations.
 408
 409         Till the feature is removed, the kernel will be requesting
 410         both sound-slot/service-* and the standard char-major-* module
 411         aliases and allow turning off the pre-claiming selectively via
 412         CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
 413         kernel parameter.
 414
 415         After the transition phase is complete, both the custom module
 416         aliases and switches to disable it will go away.  This removal
 417         will also allow making ALSA OSS emulation independent of
 418         sound_core.  The dependency will be broken then too.
 419 Who:    Tejun Heo <tj@kernel.org>
 420
 421 ----------------------------
 422
 423 What:   Support for lcd_switch and display_get in asus-laptop driver
 424 When:   March 2010
 425 Why:    These two features use non-standard interfaces. There are the
 426         only features that really need multiple path to guess what's
 427         the right method name on a specific laptop.
 428
 429         Removing them will allow to remove a lot of code an significantly
 430         clean the drivers.
 431
 432         This will affect the backlight code which won't be able to know
 433         if the backlight is on or off. The platform display file will also be
 434         write only (like the one in eeepc-laptop).
 435
 436         This should'nt affect a lot of user because they usually know
 437         when their display is on or off.
 438
 439 Who:    Corentin Chary <corentin.chary@gmail.com>
 440
 441 ----------------------------
 442
 443 What:   sysfs-class-rfkill state file
 444 When:   Feb 2014
 445 Files:  net/rfkill/core.c
 446 Why:    Documented as obsolete since Feb 2010. This file is limited to 3
 447         states while the rfkill drivers can have 4 states.
 448 Who:    anybody or Florian Mickler <florian@mickler.org>
 449
 450 ----------------------------
 451
 452 What:   sysfs-class-rfkill claim file
 453 When:   Feb 2012
 454 Files:  net/rfkill/core.c
 455 Why:    It is not possible to claim an rfkill driver since 2007. This is
 456         Documented as obsolete since Feb 2010.
 457 Who:    anybody or Florian Mickler <florian@mickler.org>
 458
 459 ----------------------------
 460
 461 What:   capifs
 462 When:   February 2011
 463 Files:  drivers/isdn/capi/capifs.*
 464 Why:    udev fully replaces this special file system that only contains CAPI
 465         NCCI TTY device nodes. User space (pppdcapiplugin) works without
 466         noticing the difference.
 467 Who:    Jan Kiszka <jan.kiszka@web.de>
 468
 469 ----------------------------
 470
 471 What:   KVM paravirt mmu host support
 472 When:   January 2011
 473 Why:    The paravirt mmu host support is slower than non-paravirt mmu, both
 474         on newer and older hardware.  It is already not exposed to the guest,
 475         and kept only for live migration purposes.
 476 Who:    Avi Kivity <avi@redhat.com>
 477
 478 ----------------------------
 479
 480 What:   iwlwifi 50XX module parameters
 481 When:   2.6.40
 482 Why:    The "..50" modules parameters were used to configure 5000 series and
 483         up devices; different set of module parameters also available for 4965
 484         with same functionalities. Consolidate both set into single place
 485         in drivers/net/wireless/iwlwifi/iwl-agn.c
 486
 487 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 488
 489 ----------------------------
 490
 491 What:   iwl4965 alias support
 492 When:   2.6.40
 493 Why:    Internal alias support has been present in module-init-tools for some
 494         time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
 495         with no impact.
 496
 497 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 498
 499 ---------------------------
 500
 501 What:   xt_NOTRACK
 502 Files:  net/netfilter/xt_NOTRACK.c
 503 When:   April 2011
 504 Why:    Superseded by xt_CT
 505 Who:    Netfilter developer team <netfilter-devel@vger.kernel.org>
 506
 507 ----------------------------
 508
 509 What:   IRQF_DISABLED
 510 When:   2.6.36
 511 Why:    The flag is a NOOP as we run interrupt handlers with interrupts disabled
 512 Who:    Thomas Gleixner <tglx@linutronix.de>
 513
 514 ----------------------------
 515
 516 What:   The acpi_sleep=s4_nonvs command line option
 517 When:   2.6.37
 518 Files:  arch/x86/kernel/acpi/sleep.c
 519 Why:    superseded by acpi_sleep=nonvs
 520 Who:    Rafael J. Wysocki <rjw@sisk.pl>
 521
 522 ----------------------------
 523
 524 What:   PCI DMA unmap state API
 525 When:   August 2012
 526 Why:    PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
 527         with DMA unmap state API (DMA unmap state API can be used for
 528         any bus).
 529 Who:    FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 530
 531 ----------------------------
 532
 533 What:   DMA_xxBIT_MASK macros
 534 When:   Jun 2011
 535 Why:    DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros.
 536 Who:    FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
 537
 538 ----------------------------
 539
 540 What:   namespace cgroup (ns_cgroup)
 541 When:   2.6.38
 542 Why:    The ns_cgroup leads to some problems:
 543         * cgroup creation is out-of-control
 544         * cgroup name can conflict when pids are looping
 545         * it is not possible to have a single process handling
 546         a lot of namespaces without falling in a exponential creation time
 547         * we may want to create a namespace without creating a cgroup
 548
 549         The ns_cgroup is replaced by a compatibility flag 'clone_children',
 550         where a newly created cgroup will copy the parent cgroup values.
 551         The userspace has to manually create a cgroup and add a task to
 552         the 'tasks' file.
 553 Who:    Daniel Lezcano <daniel.lezcano@free.fr>
 554
 555 ----------------------------
 556
 557 What:   iwlwifi disable_hw_scan module parameters
 558 When:   2.6.40
 559 Why:    Hareware scan is the prefer method for iwlwifi devices for
 560         scanning operation. Remove software scan support for all the
 561         iwlwifi devices.
 562
 563 Who:    Wey-Yi Guy <wey-yi.w.guy@intel.com>
 564
 565 ----------------------------
 566
 567 What:   access to nfsd auth cache through sys_nfsservctl or '.' files
 568         in the 'nfsd' filesystem.
 569 When:   2.6.40
 570 Why:    This is a legacy interface which have been replaced by a more
 571         dynamic cache.  Continuing to maintain this interface is an
 572         unnecessary burden.
 573 Who:    NeilBrown <neilb@suse.de>
 574
 575 ----------------------------
 576
 577 What:   i2c_adapter.id
 578 When:   June 2011
 579 Why:    This field is deprecated. I2C device drivers shouldn't change their
 580         behavior based on the underlying I2C adapter. Instead, the I2C
 581         adapter driver should instantiate the I2C devices and provide the
 582         needed platform-specific information.
 583 Who:    Jean Delvare <khali@linux-fr.org>
 584
 585 ----------------------------
 586
 587 What:   cancel_rearming_delayed_work[queue]()
 588 When:   2.6.39
 589
 590 Why:    The functions have been superceded by cancel_delayed_work_sync()
 591         quite some time ago.  The conversion is trivial and there is no
 592         in-kernel user left.
 593 Who:    Tejun Heo <tj@kernel.org>
 594
 595 ----------------------------
 596
 597 What:   Legacy, non-standard chassis intrusion detection interface.
 598 When:   June 2011
 599 Why:    The adm9240, w83792d and w83793 hardware monitoring drivers have
 600         legacy interfaces for chassis intrusion detection. A standard
 601         interface has been added to each driver, so the legacy interface
 602         can be removed.
 603 Who:    Jean Delvare <khali@linux-fr.org>
 604
 605 ----------------------------