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:   The ieee80211_regdom module parameter
  10 When:   March 2010 / desktop catchup
  11
  12 Why:    This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
  13         and currently serves as an option for users to define an
  14         ISO / IEC 3166 alpha2 code for the country they are currently
  15         present in. Although there are userspace API replacements for this
  16         through nl80211 distributions haven't yet caught up with implementing
  17         decent alternatives through standard GUIs. Although available as an
  18         option through iw or wpa_supplicant its just a matter of time before
  19         distributions pick up good GUI options for this. The ideal solution
  20         would actually consist of intelligent designs which would do this for
  21         the user automatically even when travelling through different countries.
  22         Until then we leave this module parameter as a compromise.
  23
  24         When userspace improves with reasonable widely-available alternatives for
  25         this we will no longer need this module parameter. This entry hopes that
  26         by the super-futuristically looking date of "March 2010" we will have
  27         such replacements widely available.
  28
  29 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  30
  31 ---------------------------
  32
  33 What:   CONFIG_WIRELESS_OLD_REGULATORY - old static regulatory information
  34 When:   March 2010 / desktop catchup
  35
  36 Why:    The old regulatory infrastructure has been replaced with a new one
  37         which does not require statically defined regulatory domains. We do
  38         not want to keep static regulatory domains in the kernel due to the
  39         the dynamic nature of regulatory law and localization. We kept around
  40         the old static definitions for the regulatory domains of:
  41
  42                 * US
  43                 * JP
  44                 * EU
  45
  46         and used by default the US when CONFIG_WIRELESS_OLD_REGULATORY was
  47         set. We will remove this option once the standard Linux desktop catches
  48         up with the new userspace APIs we have implemented.
  49
  50 Who:    Luis R. Rodriguez <lrodriguez@atheros.com>
  51
  52 ---------------------------
  53
  54 What:   dev->power.power_state
  55 When:   July 2007
  56 Why:    Broken design for runtime control over driver power states, confusing
  57         driver-internal runtime power management with:  mechanisms to support
  58         system-wide sleep state transitions; event codes that distinguish
  59         different phases of swsusp "sleep" transitions; and userspace policy
  60         inputs.  This framework was never widely used, and most attempts to
  61         use it were broken.  Drivers should instead be exposing domain-specific
  62         interfaces either to kernel or to userspace.
  63 Who:    Pavel Machek <pavel@suse.cz>
  64
  65 ---------------------------
  66
  67 What:   Video4Linux API 1 ioctls and from Video devices.
  68 When:   July 2009
  69 Files:  include/linux/videodev.h
  70 Check:  include/linux/videodev.h
  71 Why:    V4L1 AP1 was replaced by V4L2 API during migration from 2.4 to 2.6
  72         series. The old API have lots of drawbacks and don't provide enough
  73         means to work with all video and audio standards. The newer API is
  74         already available on the main drivers and should be used instead.
  75         Newer drivers should use v4l_compat_translate_ioctl function to handle
  76         old calls, replacing to newer ones.
  77         Decoder iocts are using internally to allow video drivers to
  78         communicate with video decoders. This should also be improved to allow
  79         V4L2 calls being translated into compatible internal ioctls.
  80         Compatibility ioctls will be provided, for a while, via
  81         v4l1-compat module.
  82 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
  83
  84 ---------------------------
  85
  86 What:   PCMCIA control ioctl (needed for pcmcia-cs [cardmgr, cardctl])
  87 When:   November 2005
  88 Files:  drivers/pcmcia/: pcmcia_ioctl.c
  89 Why:    With the 16-bit PCMCIA subsystem now behaving (almost) like a
  90         normal hotpluggable bus, and with it using the default kernel
  91         infrastructure (hotplug, driver core, sysfs) keeping the PCMCIA
  92         control ioctl needed by cardmgr and cardctl from pcmcia-cs is
  93         unnecessary, and makes further cleanups and integration of the
  94         PCMCIA subsystem into the Linux kernel device driver model more
  95         difficult. The features provided by cardmgr and cardctl are either
  96         handled by the kernel itself now or are available in the new
  97         pcmciautils package available at
  98         http://kernel.org/pub/linux/utils/kernel/pcmcia/
  99 Who:    Dominik Brodowski <linux@brodo.de>
 100
 101 ---------------------------
 102
 103 What:   sys_sysctl
 104 When:   September 2010
 105 Option: CONFIG_SYSCTL_SYSCALL
 106 Why:    The same information is available in a more convenient from
 107         /proc/sys, and none of the sysctl variables appear to be
 108         important performance wise.
 109
 110         Binary sysctls are a long standing source of subtle kernel
 111         bugs and security issues.
 112
 113         When I looked several months ago all I could find after
 114         searching several distributions were 5 user space programs and
 115         glibc (which falls back to /proc/sys) using this syscall.
 116
 117         The man page for sysctl(2) documents it as unusable for user
 118         space programs.
 119
 120         sysctl(2) is not generally ABI compatible to a 32bit user
 121         space application on a 64bit and a 32bit kernel.
 122
 123         For the last several months the policy has been no new binary
 124         sysctls and no one has put forward an argument to use them.
 125
 126         Binary sysctls issues seem to keep happening appearing so
 127         properly deprecating them (with a warning to user space) and a
 128         2 year grace warning period will mean eventually we can kill
 129         them and end the pain.
 130
 131         In the mean time individual binary sysctls can be dealt with
 132         in a piecewise fashion.
 133
 134 Who:    Eric Biederman <ebiederm@xmission.com>
 135
 136 ---------------------------
 137
 138 What:   remove EXPORT_SYMBOL(kernel_thread)
 139 When:   August 2006
 140 Files:  arch/*/kernel/*_ksyms.c
 141 Check:  kernel_thread
 142 Why:    kernel_thread is a low-level implementation detail.  Drivers should
 143         use the <linux/kthread.h> API instead which shields them from
 144         implementation details and provides a higherlevel interface that
 145         prevents bugs and code duplication
 146 Who:    Christoph Hellwig <hch@lst.de>
 147
 148 ---------------------------
 149
 150 What:   Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
 151         (temporary transition config option provided until then)
 152         The transition config option will also be removed at the same time.
 153 When:   before 2.6.19
 154 Why:    Unused symbols are both increasing the size of the kernel binary
 155         and are often a sign of "wrong API"
 156 Who:    Arjan van de Ven <arjan@linux.intel.com>
 157
 158 ---------------------------
 159
 160 What:   PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 161 When:   October 2008
 162 Why:    The stacking of class devices makes these values misleading and
 163         inconsistent.
 164         Class devices should not carry any of these properties, and bus
 165         devices have SUBSYTEM and DRIVER as a replacement.
 166 Who:    Kay Sievers <kay.sievers@suse.de>
 167
 168 ---------------------------
 169
 170 What:   ACPI procfs interface
 171 When:   July 2008
 172 Why:    ACPI sysfs conversion should be finished by January 2008.
 173         ACPI procfs interface will be removed in July 2008 so that
 174         there is enough time for the user space to catch up.
 175 Who:    Zhang Rui <rui.zhang@intel.com>
 176
 177 ---------------------------
 178
 179 What:   /proc/acpi/button
 180 When:   August 2007
 181 Why:    /proc/acpi/button has been replaced by events to the input layer
 182         since 2.6.20.
 183 Who:    Len Brown <len.brown@intel.com>
 184
 185 ---------------------------
 186
 187 What:   /proc/acpi/event
 188 When:   February 2008
 189 Why:    /proc/acpi/event has been replaced by events via the input layer
 190         and netlink since 2.6.23.
 191 Who:    Len Brown <len.brown@intel.com>
 192
 193 ---------------------------
 194
 195 What: libata spindown skipping and warning
 196 When: Dec 2008
 197 Why:  Some halt(8) implementations synchronize caches for and spin
 198       down libata disks because libata didn't use to spin down disk on
 199       system halt (only synchronized caches).
 200       Spin down on system halt is now implemented.  sysfs node
 201       /sys/class/scsi_disk/h:c:i:l/manage_start_stop is present if
 202       spin down support is available.
 203       Because issuing spin down command to an already spun down disk
 204       makes some disks spin up just to spin down again, libata tracks
 205       device spindown status to skip the extra spindown command and
 206       warn about it.
 207       This is to give userspace tools the time to get updated and will
 208       be removed after userspace is reasonably updated.
 209 Who:  Tejun Heo <htejun@gmail.com>
 210
 211 ---------------------------
 212
 213 What:   i386/x86_64 bzImage symlinks
 214 When:   April 2010
 215
 216 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 217         location so not yet updated user space tools, e.g. package
 218         scripts, do not break.
 219 Who:    Thomas Gleixner <tglx@linutronix.de>
 220
 221 ---------------------------
 222
 223 What (Why):
 224         - include/linux/netfilter_ipv4/ipt_TOS.h ipt_tos.h header files
 225           (superseded by xt_TOS/xt_tos target & match)
 226
 227         - "forwarding" header files like ipt_mac.h in
 228           include/linux/netfilter_ipv4/ and include/linux/netfilter_ipv6/
 229
 230         - xt_CONNMARK match revision 0
 231           (superseded by xt_CONNMARK match revision 1)
 232
 233         - xt_MARK target revisions 0 and 1
 234           (superseded by xt_MARK match revision 2)
 235
 236         - xt_connmark match revision 0
 237           (superseded by xt_connmark match revision 1)
 238
 239         - xt_conntrack match revision 0
 240           (superseded by xt_conntrack match revision 1)
 241
 242         - xt_iprange match revision 0,
 243           include/linux/netfilter_ipv4/ipt_iprange.h
 244           (superseded by xt_iprange match revision 1)
 245
 246         - xt_mark match revision 0
 247           (superseded by xt_mark match revision 1)
 248
 249         - xt_recent: the old ipt_recent proc dir
 250           (superseded by /proc/net/xt_recent)
 251
 252 When:   January 2009 or Linux 2.7.0, whichever comes first
 253 Why:    Superseded by newer revisions or modules
 254 Who:    Jan Engelhardt <jengelh@computergmbh.de>
 255
 256 ---------------------------
 257
 258 What:   b43 support for firmware revision < 410
 259 When:   The schedule was July 2008, but it was decided that we are going to keep the
 260         code as long as there are no major maintanance headaches.
 261         So it _could_ be removed _any_ time now, if it conflicts with something new.
 262 Why:    The support code for the old firmware hurts code readability/maintainability
 263         and slightly hurts runtime performance. Bugfixes for the old firmware
 264         are not provided by Broadcom anymore.
 265 Who:    Michael Buesch <mb@bu3sch.de>
 266
 267 ---------------------------
 268
 269 What:   usedac i386 kernel parameter
 270 When:   2.6.27
 271 Why:    replaced by allowdac and no dac combination
 272 Who:    Glauber Costa <gcosta@redhat.com>
 273
 274 ---------------------------
 275
 276 What:   remove HID compat support
 277 When:   2.6.29
 278 Why:    needed only as a temporary solution until distros fix themselves up
 279 Who:    Jiri Slaby <jirislaby@gmail.com>
 280
 281 ---------------------------
 282
 283 What: print_fn_descriptor_symbol()
 284 When: October 2009
 285 Why:  The %pF vsprintf format provides the same functionality in a
 286       simpler way.  print_fn_descriptor_symbol() is deprecated but
 287       still present to give out-of-tree modules time to change.
 288 Who:  Bjorn Helgaas <bjorn.helgaas@hp.com>
 289
 290 ---------------------------
 291
 292 What:   /sys/o2cb symlink
 293 When:   January 2010
 294 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 295         exists as a symlink for backwards compatibility for old versions of
 296         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 297         which know to look in /sys/fs/o2cb.
 298 Who:    ocfs2-devel@oss.oracle.com
 299
 300 ---------------------------
 301
 302 What:   SCTP_GET_PEER_ADDRS_NUM_OLD, SCTP_GET_PEER_ADDRS_OLD,
 303         SCTP_GET_LOCAL_ADDRS_NUM_OLD, SCTP_GET_LOCAL_ADDRS_OLD
 304 When:   June 2009
 305 Why:    A newer version of the options have been introduced in 2005 that
 306         removes the limitions of the old API.  The sctp library has been
 307         converted to use these new options at the same time.  Any user
 308         space app that directly uses the old options should convert to using
 309         the new options.
 310 Who:    Vlad Yasevich <vladislav.yasevich@hp.com>
 311
 312 ---------------------------
 313
 314 What:   Ability for non root users to shm_get hugetlb pages based on mlock
 315         resource limits
 316 When:   2.6.31
 317 Why:    Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
 318         have CAP_IPC_LOCK to be able to allocate shm segments backed by
 319         huge pages.  The mlock based rlimit check to allow shm hugetlb is
 320         inconsistent with mmap based allocations.  Hence it is being
 321         deprecated.
 322 Who:    Ravikiran Thirumalai <kiran@scalex86.org>
 323
 324 ---------------------------
 325
 326 What:   CONFIG_THERMAL_HWMON
 327 When:   January 2009
 328 Why:    This option was introduced just to allow older lm-sensors userspace
 329         to keep working over the upgrade to 2.6.26. At the scheduled time of
 330         removal fixed lm-sensors (2.x or 3.x) should be readily available.
 331 Who:    Rene Herman <rene.herman@gmail.com>
 332
 333 ---------------------------
 334
 335 What:   Code that is now under CONFIG_WIRELESS_EXT_SYSFS
 336         (in net/core/net-sysfs.c)
 337 When:   After the only user (hal) has seen a release with the patches
 338         for enough time, probably some time in 2010.
 339 Why:    Over 1K .text/.data size reduction, data is available in other
 340         ways (ioctls)
 341 Who:    Johannes Berg <johannes@sipsolutions.net>
 342
 343 ---------------------------
 344
 345 What: CONFIG_NF_CT_ACCT
 346 When: 2.6.29
 347 Why:  Accounting can now be enabled/disabled without kernel recompilation.
 348       Currently used only to set a default value for a feature that is also
 349       controlled by a kernel/module/sysfs/sysctl parameter.
 350 Who:  Krzysztof Piotr Oledzki <ole@ans.pl>
 351
 352 ---------------------------
 353
 354 What:   i2c_attach_client(), i2c_detach_client(), i2c_driver->detach_client()
 355 When:   2.6.30
 356 Check:  i2c_attach_client i2c_detach_client
 357 Why:    Deprecated by the new (standard) device driver binding model. Use
 358         i2c_driver->probe() and ->remove() instead.
 359 Who:    Jean Delvare <khali@linux-fr.org>
 360
 361 ---------------------------
 362
 363 What:   fscher and fscpos drivers
 364 When:   June 2009
 365 Why:    Deprecated by the new fschmd driver.
 366 Who:    Hans de Goede <hdegoede@redhat.com>
 367         Jean Delvare <khali@linux-fr.org>
 368
 369 ---------------------------
 370
 371 What:   sysfs ui for changing p4-clockmod parameters
 372 When:   September 2009
 373 Why:    See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
 374         e088e4c9cdb618675874becb91b2fd581ee707e6.
 375         Removal is subject to fixing any remaining bugs in ACPI which may
 376         cause the thermal throttling not to happen at the right time.
 377 Who:    Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
 378
 379 -----------------------------
 380
 381 What:   __do_IRQ all in one fits nothing interrupt handler
 382 When:   2.6.32
 383 Why:    __do_IRQ was kept for easy migration to the type flow handlers.
 384         More than two years of migration time is enough.
 385 Who:    Thomas Gleixner <tglx@linutronix.de>
 386
 387 -----------------------------
 388
 389 What:   obsolete generic irq defines and typedefs
 390 When:   2.6.30
 391 Why:    The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t)
 392         have been kept around for migration reasons. After more than two years
 393         it's time to remove them finally
 394 Who:    Thomas Gleixner <tglx@linutronix.de>