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:   IRQF_SAMPLE_RANDOM
  10 Check:  IRQF_SAMPLE_RANDOM
  11 When:   July 2009
  12
  13 Why:    Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
  14         sources in the kernel's current entropy model. To resolve this, every
  15         input point to the kernel's entropy pool needs to better document the
  16         type of entropy source it actually is. This will be replaced with
  17         additional add_*_randomness functions in drivers/char/random.c
  18
  19 Who:    Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
  20
  21 ---------------------------
  22
  23 What:   The ieee80211_regdom module parameter
  24 When:   March 2010 / desktop catchup
  25
  26 Why:    This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
  27         and currently serves as an option for users to define an
  28         ISO / IEC 3166 alpha2 code for the country they are currently
  29         present in. Although there are userspace API replacements for this
  30         through nl80211 distributions haven't yet caught up with implementing
  31         decent alternatives through standard GUIs. Although available as an
  32         option through iw or wpa_supplicant its just a matter of time before
  33         distributions pick up good GUI options for this. The ideal solution
  34         would actually consist of intelligent designs which would do this for
  35         the user automatically even when travelling through different countries.
  36         Until then we leave this module parameter as a compromise.
  37
  38         When userspace improves with reasonable widely-available alternatives for
  39         this we will no longer need this module parameter. This entry hopes that
  40         by the super-futuristically looking date of "March 2010" we will have
  41         such replacements widely available.
  42
  43 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  44
  45 ---------------------------
  46
  47 What:   CONFIG_WIRELESS_OLD_REGULATORY - old static regulatory information
  48 When:   March 2010 / desktop catchup
  49
  50 Why:    The old regulatory infrastructure has been replaced with a new one
  51         which does not require statically defined regulatory domains. We do
  52         not want to keep static regulatory domains in the kernel due to the
  53         the dynamic nature of regulatory law and localization. We kept around
  54         the old static definitions for the regulatory domains of:
  55
  56                 * US
  57                 * JP
  58                 * EU
  59
  60         and used by default the US when CONFIG_WIRELESS_OLD_REGULATORY was
  61         set. We will remove this option once the standard Linux desktop catches
  62         up with the new userspace APIs we have implemented.
  63
  64 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  65
  66 ---------------------------
  67
  68 What:   dev->power.power_state
  69 When:   July 2007
  70 Why:    Broken design for runtime control over driver power states, confusing
  71         driver-internal runtime power management with:  mechanisms to support
  72         system-wide sleep state transitions; event codes that distinguish
  73         different phases of swsusp "sleep" transitions; and userspace policy
  74         inputs.  This framework was never widely used, and most attempts to
  75         use it were broken.  Drivers should instead be exposing domain-specific
  76         interfaces either to kernel or to userspace.
  77 Who:    Pavel Machek <pavel@suse.cz>
  78
  79 ---------------------------
  80
  81 What:   Video4Linux API 1 ioctls and from Video devices.
  82 When:   July 2009
  83 Files:  include/linux/videodev.h
  84 Check:  include/linux/videodev.h
  85 Why:    V4L1 AP1 was replaced by V4L2 API during migration from 2.4 to 2.6
  86         series. The old API have lots of drawbacks and don't provide enough
  87         means to work with all video and audio standards. The newer API is
  88         already available on the main drivers and should be used instead.
  89         Newer drivers should use v4l_compat_translate_ioctl function to handle
  90         old calls, replacing to newer ones.
  91         Decoder iocts are using internally to allow video drivers to
  92         communicate with video decoders. This should also be improved to allow
  93         V4L2 calls being translated into compatible internal ioctls.
  94         Compatibility ioctls will be provided, for a while, via
  95         v4l1-compat module.
  96 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
  97
  98 ---------------------------
  99
 100 What:   PCMCIA control ioctl (needed for pcmcia-cs [cardmgr, cardctl])
 101 When:   November 2005
 102 Files:  drivers/pcmcia/: pcmcia_ioctl.c
 103 Why:    With the 16-bit PCMCIA subsystem now behaving (almost) like a
 104         normal hotpluggable bus, and with it using the default kernel
 105         infrastructure (hotplug, driver core, sysfs) keeping the PCMCIA
 106         control ioctl needed by cardmgr and cardctl from pcmcia-cs is
 107         unnecessary, and makes further cleanups and integration of the
 108         PCMCIA subsystem into the Linux kernel device driver model more
 109         difficult. The features provided by cardmgr and cardctl are either
 110         handled by the kernel itself now or are available in the new
 111         pcmciautils package available at
 112         http://kernel.org/pub/linux/utils/kernel/pcmcia/
 113 Who:    Dominik Brodowski <linux@brodo.de>
 114
 115 ---------------------------
 116
 117 What:   sys_sysctl
 118 When:   September 2010
 119 Option: CONFIG_SYSCTL_SYSCALL
 120 Why:    The same information is available in a more convenient from
 121         /proc/sys, and none of the sysctl variables appear to be
 122         important performance wise.
 123
 124         Binary sysctls are a long standing source of subtle kernel
 125         bugs and security issues.
 126
 127         When I looked several months ago all I could find after
 128         searching several distributions were 5 user space programs and
 129         glibc (which falls back to /proc/sys) using this syscall.
 130
 131         The man page for sysctl(2) documents it as unusable for user
 132         space programs.
 133
 134         sysctl(2) is not generally ABI compatible to a 32bit user
 135         space application on a 64bit and a 32bit kernel.
 136
 137         For the last several months the policy has been no new binary
 138         sysctls and no one has put forward an argument to use them.
 139
 140         Binary sysctls issues seem to keep happening appearing so
 141         properly deprecating them (with a warning to user space) and a
 142         2 year grace warning period will mean eventually we can kill
 143         them and end the pain.
 144
 145         In the mean time individual binary sysctls can be dealt with
 146         in a piecewise fashion.
 147
 148 Who:    Eric Biederman <ebiederm@xmission.com>
 149
 150 ---------------------------
 151
 152 What:   remove EXPORT_SYMBOL(kernel_thread)
 153 When:   August 2006
 154 Files:  arch/*/kernel/*_ksyms.c
 155 Check:  kernel_thread
 156 Why:    kernel_thread is a low-level implementation detail.  Drivers should
 157         use the <linux/kthread.h> API instead which shields them from
 158         implementation details and provides a higherlevel interface that
 159         prevents bugs and code duplication
 160 Who:    Christoph Hellwig <hch@lst.de>
 161
 162 ---------------------------
 163
 164 What:   Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
 165         (temporary transition config option provided until then)
 166         The transition config option will also be removed at the same time.
 167 When:   before 2.6.19
 168 Why:    Unused symbols are both increasing the size of the kernel binary
 169         and are often a sign of "wrong API"
 170 Who:    Arjan van de Ven <arjan@linux.intel.com>
 171
 172 ---------------------------
 173
 174 What:   PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 175 When:   October 2008
 176 Why:    The stacking of class devices makes these values misleading and
 177         inconsistent.
 178         Class devices should not carry any of these properties, and bus
 179         devices have SUBSYTEM and DRIVER as a replacement.
 180 Who:    Kay Sievers <kay.sievers@suse.de>
 181
 182 ---------------------------
 183
 184 What:   ACPI procfs interface
 185 When:   July 2008
 186 Why:    ACPI sysfs conversion should be finished by January 2008.
 187         ACPI procfs interface will be removed in July 2008 so that
 188         there is enough time for the user space to catch up.
 189 Who:    Zhang Rui <rui.zhang@intel.com>
 190
 191 ---------------------------
 192
 193 What:   /proc/acpi/button
 194 When:   August 2007
 195 Why:    /proc/acpi/button has been replaced by events to the input layer
 196         since 2.6.20.
 197 Who:    Len Brown <len.brown@intel.com>
 198
 199 ---------------------------
 200
 201 What:   /proc/acpi/event
 202 When:   February 2008
 203 Why:    /proc/acpi/event has been replaced by events via the input layer
 204         and netlink since 2.6.23.
 205 Who:    Len Brown <len.brown@intel.com>
 206
 207 ---------------------------
 208
 209 What: libata spindown skipping and warning
 210 When: Dec 2008
 211 Why:  Some halt(8) implementations synchronize caches for and spin
 212       down libata disks because libata didn't use to spin down disk on
 213       system halt (only synchronized caches).
 214       Spin down on system halt is now implemented.  sysfs node
 215       /sys/class/scsi_disk/h:c:i:l/manage_start_stop is present if
 216       spin down support is available.
 217       Because issuing spin down command to an already spun down disk
 218       makes some disks spin up just to spin down again, libata tracks
 219       device spindown status to skip the extra spindown command and
 220       warn about it.
 221       This is to give userspace tools the time to get updated and will
 222       be removed after userspace is reasonably updated.
 223 Who:  Tejun Heo <htejun@gmail.com>
 224
 225 ---------------------------
 226
 227 What:   i386/x86_64 bzImage symlinks
 228 When:   April 2010
 229
 230 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 231         location so not yet updated user space tools, e.g. package
 232         scripts, do not break.
 233 Who:    Thomas Gleixner <tglx@linutronix.de>
 234
 235 ---------------------------
 236
 237 What (Why):
 238         - "forwarding" header files like ipt_mac.h in
 239           include/linux/netfilter_ipv4/ and include/linux/netfilter_ipv6/
 240
 241         - xt_recent: the old ipt_recent proc dir
 242           (superseded by /proc/net/xt_recent)
 243
 244 When:   January 2009 or Linux 2.7.0, whichever comes first
 245 Why:    Superseded by newer revisions or modules
 246 Who:    Jan Engelhardt <jengelh@computergmbh.de>
 247
 248 ---------------------------
 249
 250 What:   GPIO autorequest on gpio_direction_{input,output}() in gpiolib
 251 When:   February 2010
 252 Why:    All callers should use explicit gpio_request()/gpio_free().
 253         The autorequest mechanism in gpiolib was provided mostly as a
 254         migration aid for legacy GPIO interfaces (for SOC based GPIOs).
 255         Those users have now largely migrated.  Platforms implementing
 256         the GPIO interfaces without using gpiolib will see no changes.
 257 Who:    David Brownell <dbrownell@users.sourceforge.net>
 258 ---------------------------
 259
 260 What:   b43 support for firmware revision < 410
 261 When:   The schedule was July 2008, but it was decided that we are going to keep the
 262         code as long as there are no major maintanance headaches.
 263         So it _could_ be removed _any_ time now, if it conflicts with something new.
 264 Why:    The support code for the old firmware hurts code readability/maintainability
 265         and slightly hurts runtime performance. Bugfixes for the old firmware
 266         are not provided by Broadcom anymore.
 267 Who:    Michael Buesch <mb@bu3sch.de>
 268
 269 ---------------------------
 270
 271 What:   usedac i386 kernel parameter
 272 When:   2.6.27
 273 Why:    replaced by allowdac and no dac combination
 274 Who:    Glauber Costa <gcosta@redhat.com>
 275
 276 ---------------------------
 277
 278 What: print_fn_descriptor_symbol()
 279 When: October 2009
 280 Why:  The %pF vsprintf format provides the same functionality in a
 281       simpler way.  print_fn_descriptor_symbol() is deprecated but
 282       still present to give out-of-tree modules time to change.
 283 Who:  Bjorn Helgaas <bjorn.helgaas@hp.com>
 284
 285 ---------------------------
 286
 287 What:   /sys/o2cb symlink
 288 When:   January 2010
 289 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 290         exists as a symlink for backwards compatibility for old versions of
 291         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 292         which know to look in /sys/fs/o2cb.
 293 Who:    ocfs2-devel@oss.oracle.com
 294
 295 ---------------------------
 296
 297 What:   SCTP_GET_PEER_ADDRS_NUM_OLD, SCTP_GET_PEER_ADDRS_OLD,
 298         SCTP_GET_LOCAL_ADDRS_NUM_OLD, SCTP_GET_LOCAL_ADDRS_OLD
 299 When:   June 2009
 300 Why:    A newer version of the options have been introduced in 2005 that
 301         removes the limitions of the old API.  The sctp library has been
 302         converted to use these new options at the same time.  Any user
 303         space app that directly uses the old options should convert to using
 304         the new options.
 305 Who:    Vlad Yasevich <vladislav.yasevich@hp.com>
 306
 307 ---------------------------
 308
 309 What:   Ability for non root users to shm_get hugetlb pages based on mlock
 310         resource limits
 311 When:   2.6.31
 312 Why:    Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
 313         have CAP_IPC_LOCK to be able to allocate shm segments backed by
 314         huge pages.  The mlock based rlimit check to allow shm hugetlb is
 315         inconsistent with mmap based allocations.  Hence it is being
 316         deprecated.
 317 Who:    Ravikiran Thirumalai <kiran@scalex86.org>
 318
 319 ---------------------------
 320
 321 What:   CONFIG_THERMAL_HWMON
 322 When:   January 2009
 323 Why:    This option was introduced just to allow older lm-sensors userspace
 324         to keep working over the upgrade to 2.6.26. At the scheduled time of
 325         removal fixed lm-sensors (2.x or 3.x) should be readily available.
 326 Who:    Rene Herman <rene.herman@gmail.com>
 327
 328 ---------------------------
 329
 330 What:   Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 331         (in net/core/net-sysfs.c)
 332 When:   After the only user (hal) has seen a release with the patches
 333         for enough time, probably some time in 2010.
 334 Why:    Over 1K .text/.data size reduction, data is available in other
 335         ways (ioctls)
 336 Who:    Johannes Berg <johannes@sipsolutions.net>
 337
 338 ---------------------------
 339
 340 What: CONFIG_NF_CT_ACCT
 341 When: 2.6.29
 342 Why:  Accounting can now be enabled/disabled without kernel recompilation.
 343       Currently used only to set a default value for a feature that is also
 344       controlled by a kernel/module/sysfs/sysctl parameter.
 345 Who:  Krzysztof Piotr Oledzki <ole@ans.pl>
 346
 347 ---------------------------
 348
 349 What:   fscher and fscpos drivers
 350 When:   June 2009
 351 Why:    Deprecated by the new fschmd driver.
 352 Who:    Hans de Goede <hdegoede@redhat.com>
 353         Jean Delvare <khali@linux-fr.org>
 354
 355 ---------------------------
 356
 357 What:   sysfs ui for changing p4-clockmod parameters
 358 When:   September 2009
 359 Why:    See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
 360         e088e4c9cdb618675874becb91b2fd581ee707e6.
 361         Removal is subject to fixing any remaining bugs in ACPI which may
 362         cause the thermal throttling not to happen at the right time.
 363 Who:    Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
 364
 365 -----------------------------
 366
 367 What:   __do_IRQ all in one fits nothing interrupt handler
 368 When:   2.6.32
 369 Why:    __do_IRQ was kept for easy migration to the type flow handlers.
 370         More than two years of migration time is enough.
 371 Who:    Thomas Gleixner <tglx@linutronix.de>
 372
 373 -----------------------------
 374
 375 What:   obsolete generic irq defines and typedefs
 376 When:   2.6.30
 377 Why:    The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t)
 378         have been kept around for migration reasons. After more than two years
 379         it's time to remove them finally
 380 Who:    Thomas Gleixner <tglx@linutronix.de>
 381
 382 ---------------------------
 383
 384 What:   fakephp and associated sysfs files in /sys/bus/pci/slots/
 385 When:   2011
 386 Why:    In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
 387         represent a machine's physical PCI slots. The change in semantics
 388         had userspace implications, as the hotplug core no longer allowed
 389         drivers to create multiple sysfs files per physical slot (required
 390         for multi-function devices, e.g.). fakephp was seen as a developer's
 391         tool only, and its interface changed. Too late, we learned that
 392         there were some users of the fakephp interface.
 393
 394         In 2.6.30, the original fakephp interface was restored. At the same
 395         time, the PCI core gained the ability that fakephp provided, namely
 396         function-level hot-remove and hot-add.
 397
 398         Since the PCI core now provides the same functionality, exposed in:
 399
 400                 /sys/bus/pci/rescan
 401                 /sys/bus/pci/devices/.../remove
 402                 /sys/bus/pci/devices/.../rescan
 403
 404         there is no functional reason to maintain fakephp as well.
 405
 406         We will keep the existing module so that 'modprobe fakephp' will
 407         present the old /sys/bus/pci/slots/... interface for compatibility,
 408         but users are urged to migrate their applications to the API above.
 409
 410         After a reasonable transition period, we will remove the legacy
 411         fakephp interface.
 412 Who:    Alex Chiang <achiang@hp.com>
 413
 414 ---------------------------
 415
 416 What:   i2c-voodoo3 driver
 417 When:   October 2009
 418 Why:    Superseded by tdfxfb. I2C/DDC support used to live in a separate
 419         driver but this caused driver conflicts.
 420 Who:    Jean Delvare <khali@linux-fr.org>
 421         Krzysztof Helt <krzysztof.h1@wp.pl>
 422
 423 ---------------------------
 424
 425 What:   CONFIG_RFKILL_INPUT
 426 When:   2.6.33
 427 Why:    Should be implemented in userspace, policy daemon.
 428 Who:    Johannes Berg <johannes@sipsolutions.net>
 429
 430 ----------------------------
 431
 432 What:   CONFIG_X86_OLD_MCE
 433 When:   2.6.32
 434 Why:    Remove the old legacy 32bit machine check code. This has been
 435         superseded by the newer machine check code from the 64bit port,
 436         but the old version has been kept around for easier testing. Note this
 437         doesn't impact the old P5 and WinChip machine check handlers.
 438 Who:    Andi Kleen <andi@firstfloor.org>