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:   i386/x86_64 bzImage symlinks
 210 When:   April 2010
 211
 212 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 213         location so not yet updated user space tools, e.g. package
 214         scripts, do not break.
 215 Who:    Thomas Gleixner <tglx@linutronix.de>
 216
 217 ---------------------------
 218
 219 What (Why):
 220         - include/linux/netfilter_ipv4/ipt_TOS.h ipt_tos.h header files
 221           (superseded by xt_TOS/xt_tos target & match)
 222
 223         - "forwarding" header files like ipt_mac.h in
 224           include/linux/netfilter_ipv4/ and include/linux/netfilter_ipv6/
 225
 226         - xt_CONNMARK match revision 0
 227           (superseded by xt_CONNMARK match revision 1)
 228
 229         - xt_MARK target revisions 0 and 1
 230           (superseded by xt_MARK match revision 2)
 231
 232         - xt_connmark match revision 0
 233           (superseded by xt_connmark match revision 1)
 234
 235         - xt_conntrack match revision 0
 236           (superseded by xt_conntrack match revision 1)
 237
 238         - xt_iprange match revision 0,
 239           include/linux/netfilter_ipv4/ipt_iprange.h
 240           (superseded by xt_iprange match revision 1)
 241
 242         - xt_mark match revision 0
 243           (superseded by xt_mark match revision 1)
 244
 245         - xt_recent: the old ipt_recent proc dir
 246           (superseded by /proc/net/xt_recent)
 247
 248 When:   January 2009 or Linux 2.7.0, whichever comes first
 249 Why:    Superseded by newer revisions or modules
 250 Who:    Jan Engelhardt <jengelh@computergmbh.de>
 251
 252 ---------------------------
 253
 254 What:   GPIO autorequest on gpio_direction_{input,output}() in gpiolib
 255 When:   February 2010
 256 Why:    All callers should use explicit gpio_request()/gpio_free().
 257         The autorequest mechanism in gpiolib was provided mostly as a
 258         migration aid for legacy GPIO interfaces (for SOC based GPIOs).
 259         Those users have now largely migrated.  Platforms implementing
 260         the GPIO interfaces without using gpiolib will see no changes.
 261 Who:    David Brownell <dbrownell@users.sourceforge.net>
 262 ---------------------------
 263
 264 What:   b43 support for firmware revision < 410
 265 When:   The schedule was July 2008, but it was decided that we are going to keep the
 266         code as long as there are no major maintanance headaches.
 267         So it _could_ be removed _any_ time now, if it conflicts with something new.
 268 Why:    The support code for the old firmware hurts code readability/maintainability
 269         and slightly hurts runtime performance. Bugfixes for the old firmware
 270         are not provided by Broadcom anymore.
 271 Who:    Michael Buesch <mb@bu3sch.de>
 272
 273 ---------------------------
 274
 275 What:   usedac i386 kernel parameter
 276 When:   2.6.27
 277 Why:    replaced by allowdac and no dac combination
 278 Who:    Glauber Costa <gcosta@redhat.com>
 279
 280 ---------------------------
 281
 282 What: print_fn_descriptor_symbol()
 283 When: October 2009
 284 Why:  The %pF vsprintf format provides the same functionality in a
 285       simpler way.  print_fn_descriptor_symbol() is deprecated but
 286       still present to give out-of-tree modules time to change.
 287 Who:  Bjorn Helgaas <bjorn.helgaas@hp.com>
 288
 289 ---------------------------
 290
 291 What:   /sys/o2cb symlink
 292 When:   January 2010
 293 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 294         exists as a symlink for backwards compatibility for old versions of
 295         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 296         which know to look in /sys/fs/o2cb.
 297 Who:    ocfs2-devel@oss.oracle.com
 298
 299 ---------------------------
 300
 301 What:   SCTP_GET_PEER_ADDRS_NUM_OLD, SCTP_GET_PEER_ADDRS_OLD,
 302         SCTP_GET_LOCAL_ADDRS_NUM_OLD, SCTP_GET_LOCAL_ADDRS_OLD
 303 When:   June 2009
 304 Why:    A newer version of the options have been introduced in 2005 that
 305         removes the limitions of the old API.  The sctp library has been
 306         converted to use these new options at the same time.  Any user
 307         space app that directly uses the old options should convert to using
 308         the new options.
 309 Who:    Vlad Yasevich <vladislav.yasevich@hp.com>
 310
 311 ---------------------------
 312
 313 What:   Ability for non root users to shm_get hugetlb pages based on mlock
 314         resource limits
 315 When:   2.6.31
 316 Why:    Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
 317         have CAP_IPC_LOCK to be able to allocate shm segments backed by
 318         huge pages.  The mlock based rlimit check to allow shm hugetlb is
 319         inconsistent with mmap based allocations.  Hence it is being
 320         deprecated.
 321 Who:    Ravikiran Thirumalai <kiran@scalex86.org>
 322
 323 ---------------------------
 324
 325 What:   CONFIG_THERMAL_HWMON
 326 When:   January 2009
 327 Why:    This option was introduced just to allow older lm-sensors userspace
 328         to keep working over the upgrade to 2.6.26. At the scheduled time of
 329         removal fixed lm-sensors (2.x or 3.x) should be readily available.
 330 Who:    Rene Herman <rene.herman@gmail.com>
 331
 332 ---------------------------
 333
 334 What:   Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 335         (in net/core/net-sysfs.c)
 336 When:   After the only user (hal) has seen a release with the patches
 337         for enough time, probably some time in 2010.
 338 Why:    Over 1K .text/.data size reduction, data is available in other
 339         ways (ioctls)
 340 Who:    Johannes Berg <johannes@sipsolutions.net>
 341
 342 ---------------------------
 343
 344 What: CONFIG_NF_CT_ACCT
 345 When: 2.6.29
 346 Why:  Accounting can now be enabled/disabled without kernel recompilation.
 347       Currently used only to set a default value for a feature that is also
 348       controlled by a kernel/module/sysfs/sysctl parameter.
 349 Who:  Krzysztof Piotr Oledzki <ole@ans.pl>
 350
 351 ---------------------------
 352
 353 What:   fscher and fscpos drivers
 354 When:   June 2009
 355 Why:    Deprecated by the new fschmd driver.
 356 Who:    Hans de Goede <hdegoede@redhat.com>
 357         Jean Delvare <khali@linux-fr.org>
 358
 359 ---------------------------
 360
 361 What:   sysfs ui for changing p4-clockmod parameters
 362 When:   September 2009
 363 Why:    See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
 364         e088e4c9cdb618675874becb91b2fd581ee707e6.
 365         Removal is subject to fixing any remaining bugs in ACPI which may
 366         cause the thermal throttling not to happen at the right time.
 367 Who:    Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
 368
 369 -----------------------------
 370
 371 What:   __do_IRQ all in one fits nothing interrupt handler
 372 When:   2.6.32
 373 Why:    __do_IRQ was kept for easy migration to the type flow handlers.
 374         More than two years of migration time is enough.
 375 Who:    Thomas Gleixner <tglx@linutronix.de>
 376
 377 -----------------------------
 378
 379 What:   obsolete generic irq defines and typedefs
 380 When:   2.6.30
 381 Why:    The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t)
 382         have been kept around for migration reasons. After more than two years
 383         it's time to remove them finally
 384 Who:    Thomas Gleixner <tglx@linutronix.de>
 385
 386 ---------------------------
 387
 388 What:   fakephp and associated sysfs files in /sys/bus/pci/slots/
 389 When:   2011
 390 Why:    In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
 391         represent a machine's physical PCI slots. The change in semantics
 392         had userspace implications, as the hotplug core no longer allowed
 393         drivers to create multiple sysfs files per physical slot (required
 394         for multi-function devices, e.g.). fakephp was seen as a developer's
 395         tool only, and its interface changed. Too late, we learned that
 396         there were some users of the fakephp interface.
 397
 398         In 2.6.30, the original fakephp interface was restored. At the same
 399         time, the PCI core gained the ability that fakephp provided, namely
 400         function-level hot-remove and hot-add.
 401
 402         Since the PCI core now provides the same functionality, exposed in:
 403
 404                 /sys/bus/pci/rescan
 405                 /sys/bus/pci/devices/.../remove
 406                 /sys/bus/pci/devices/.../rescan
 407
 408         there is no functional reason to maintain fakephp as well.
 409
 410         We will keep the existing module so that 'modprobe fakephp' will
 411         present the old /sys/bus/pci/slots/... interface for compatibility,
 412         but users are urged to migrate their applications to the API above.
 413
 414         After a reasonable transition period, we will remove the legacy
 415         fakephp interface.
 416 Who:    Alex Chiang <achiang@hp.com>
 417
 418 ---------------------------
 419
 420 What:   i2c-voodoo3 driver
 421 When:   October 2009
 422 Why:    Superseded by tdfxfb. I2C/DDC support used to live in a separate
 423         driver but this caused driver conflicts.
 424 Who:    Jean Delvare <khali@linux-fr.org>
 425         Krzysztof Helt <krzysztof.h1@wp.pl>
 426
 427 ---------------------------
 428
 429 What:   CONFIG_RFKILL_INPUT
 430 When:   2.6.33
 431 Why:    Should be implemented in userspace, policy daemon.
 432 Who:    Johannes Berg <johannes@sipsolutions.net>
 433
 434 ----------------------------
 435
 436 What:   CONFIG_X86_OLD_MCE
 437 When:   2.6.32
 438 Why:    Remove the old legacy 32bit machine check code. This has been
 439         superseded by the newer machine check code from the 64bit port,
 440         but the old version has been kept around for easier testing. Note this
 441         doesn't impact the old P5 and WinChip machine check handlers.
 442 Who:    Andi Kleen <andi@firstfloor.org>
 443
 444 ----------------------------
 445
 446 What:   lock_policy_rwsem_* and unlock_policy_rwsem_* will not be
 447         exported interface anymore.
 448 When:   2.6.33
 449 Why:    cpu_policy_rwsem has a new cleaner definition making it local to
 450         cpufreq core and contained inside cpufreq.c. Other dependent
 451         drivers should not use it in order to safely avoid lockdep issues.
 452 Who:    Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>