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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.
7 ---------------------------
9 What: PRISM54
10 When: 2.6.34
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
30 For more information see the p54 wiki page:
32 http://wireless.kernel.org/en/users/Drivers/p54
34 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
36 ---------------------------
38 What: IRQF_SAMPLE_RANDOM
39 Check: IRQF_SAMPLE_RANDOM
40 When: July 2009
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
48 Who: Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
50 ---------------------------
52 What: Deprecated snapshot ioctls
53 When: 2.6.36
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.
59 Who: Jiri Slaby <jirislaby@gmail.com>
61 ---------------------------
63 What: The ieee80211_regdom module parameter
64 When: March 2010 / desktop catchup
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.
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.
83 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
85 ---------------------------
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>
98 ---------------------------
100 What: Video4Linux API 1 ioctls and from Video devices.
101 When: kernel 2.6.38
102 Files: include/linux/videodev.h
103 Check: include/linux/videodev.h
104 Why: V4L1 AP1 was replaced by V4L2 API during migration from 2.4 to 2.6
105 series. The old API have lots of drawbacks and don't provide enough
106 means to work with all video and audio standards. The newer API is
107 already available on the main drivers and should be used instead.
108 Newer drivers should use v4l_compat_translate_ioctl function to handle
109 old calls, replacing to newer ones.
110 Decoder iocts are using internally to allow video drivers to
111 communicate with video decoders. This should also be improved to allow
112 V4L2 calls being translated into compatible internal ioctls.
113 Compatibility ioctls will be provided, for a while, via
114 v4l1-compat module.
115 Who: Mauro Carvalho Chehab <mchehab@infradead.org>
117 ---------------------------
119 What: Video4Linux obsolete drivers using V4L1 API
120 When: kernel 2.6.38
121 Files: drivers/staging/cpia/* drivers/staging/stradis/*
122 Check: drivers/staging/cpia/cpia.c drivers/staging/stradis/stradis.c
123 Why: There are some drivers still using V4L1 API, despite all efforts we've done
124 to migrate. Those drivers are for obsolete hardware that the old maintainer
125 didn't care (or not have the hardware anymore), and that no other developer
126 could find any hardware to buy. They probably have no practical usage today,
127 and people with such old hardware could probably keep using an older version
128 of the kernel. Those drivers will be moved to staging on 2.6.37 and, if nobody
129 care enough to port and test them with V4L2 API, they'll be removed on 2.6.38.
130 Who: Mauro Carvalho Chehab <mchehab@infradead.org>
132 ---------------------------
134 What: sys_sysctl
135 When: September 2010
136 Option: CONFIG_SYSCTL_SYSCALL
137 Why: The same information is available in a more convenient from
138 /proc/sys, and none of the sysctl variables appear to be
139 important performance wise.
141 Binary sysctls are a long standing source of subtle kernel
142 bugs and security issues.
144 When I looked several months ago all I could find after
145 searching several distributions were 5 user space programs and
146 glibc (which falls back to /proc/sys) using this syscall.
148 The man page for sysctl(2) documents it as unusable for user
149 space programs.
151 sysctl(2) is not generally ABI compatible to a 32bit user
152 space application on a 64bit and a 32bit kernel.
154 For the last several months the policy has been no new binary
155 sysctls and no one has put forward an argument to use them.
157 Binary sysctls issues seem to keep happening appearing so
158 properly deprecating them (with a warning to user space) and a
159 2 year grace warning period will mean eventually we can kill
160 them and end the pain.
162 In the mean time individual binary sysctls can be dealt with
163 in a piecewise fashion.
165 Who: Eric Biederman <ebiederm@xmission.com>
167 ---------------------------
169 What: /proc/<pid>/oom_adj
170 When: August 2012
171 Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
172 badness heuristic used to determine which task to kill when the kernel
173 is out of memory.
175 The badness heuristic has since been rewritten since the introduction of
176 this tunable such that its meaning is deprecated. The value was
177 implemented as a bitshift on a score generated by the badness()
178 function that did not have any precise units of measure. With the
179 rewrite, the score is given as a proportion of available memory to the
180 task allocating pages, so using a bitshift which grows the score
181 exponentially is, thus, impossible to tune with fine granularity.
183 A much more powerful interface, /proc/<pid>/oom_score_adj, was
184 introduced with the oom killer rewrite that allows users to increase or
185 decrease the badness() score linearly. This interface will replace
186 /proc/<pid>/oom_adj.
188 A warning will be emitted to the kernel log if an application uses this
189 deprecated interface. After it is printed once, future warnings will be
190 suppressed until the kernel is rebooted.
192 ---------------------------
194 What: remove EXPORT_SYMBOL(kernel_thread)
195 When: August 2006
196 Files: arch/*/kernel/*_ksyms.c
197 Check: kernel_thread
198 Why: kernel_thread is a low-level implementation detail. Drivers should
199 use the <linux/kthread.h> API instead which shields them from
200 implementation details and provides a higherlevel interface that
201 prevents bugs and code duplication
202 Who: Christoph Hellwig <hch@lst.de>
204 ---------------------------
206 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
207 (temporary transition config option provided until then)
208 The transition config option will also be removed at the same time.
209 When: before 2.6.19
210 Why: Unused symbols are both increasing the size of the kernel binary
211 and are often a sign of "wrong API"
212 Who: Arjan van de Ven <arjan@linux.intel.com>
214 ---------------------------
216 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
217 When: October 2008
218 Why: The stacking of class devices makes these values misleading and
219 inconsistent.
220 Class devices should not carry any of these properties, and bus
221 devices have SUBSYTEM and DRIVER as a replacement.
222 Who: Kay Sievers <kay.sievers@suse.de>
224 ---------------------------
226 What: ACPI procfs interface
227 When: July 2008
228 Why: ACPI sysfs conversion should be finished by January 2008.
229 ACPI procfs interface will be removed in July 2008 so that
230 there is enough time for the user space to catch up.
231 Who: Zhang Rui <rui.zhang@intel.com>
233 ---------------------------
235 What: /proc/acpi/button
236 When: August 2007
237 Why: /proc/acpi/button has been replaced by events to the input layer
238 since 2.6.20.
239 Who: Len Brown <len.brown@intel.com>
241 ---------------------------
243 What: /proc/acpi/event
244 When: February 2008
245 Why: /proc/acpi/event has been replaced by events via the input layer
246 and netlink since 2.6.23.
247 Who: Len Brown <len.brown@intel.com>
249 ---------------------------
251 What: i386/x86_64 bzImage symlinks
252 When: April 2010
254 Why: The i386/x86_64 merge provides a symlink to the old bzImage
255 location so not yet updated user space tools, e.g. package
256 scripts, do not break.
257 Who: Thomas Gleixner <tglx@linutronix.de>
259 ---------------------------
261 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
262 When: February 2010
263 Why: All callers should use explicit gpio_request()/gpio_free().
264 The autorequest mechanism in gpiolib was provided mostly as a
265 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
266 Those users have now largely migrated. Platforms implementing
267 the GPIO interfaces without using gpiolib will see no changes.
268 Who: David Brownell <dbrownell@users.sourceforge.net>
269 ---------------------------
271 What: b43 support for firmware revision < 410
272 When: The schedule was July 2008, but it was decided that we are going to keep the
273 code as long as there are no major maintanance headaches.
274 So it _could_ be removed _any_ time now, if it conflicts with something new.
275 Why: The support code for the old firmware hurts code readability/maintainability
276 and slightly hurts runtime performance. Bugfixes for the old firmware
277 are not provided by Broadcom anymore.
278 Who: Michael Buesch <mb@bu3sch.de>
280 ---------------------------
282 What: /sys/o2cb symlink
283 When: January 2010
284 Why: /sys/fs/o2cb is the proper location for this information - /sys/o2cb
285 exists as a symlink for backwards compatibility for old versions of
286 ocfs2-tools. 2 years should be sufficient time to phase in new versions
287 which know to look in /sys/fs/o2cb.
288 Who: ocfs2-devel@oss.oracle.com
290 ---------------------------
292 What: Ability for non root users to shm_get hugetlb pages based on mlock
293 resource limits
294 When: 2.6.31
295 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
296 have CAP_IPC_LOCK to be able to allocate shm segments backed by
297 huge pages. The mlock based rlimit check to allow shm hugetlb is
298 inconsistent with mmap based allocations. Hence it is being
299 deprecated.
300 Who: Ravikiran Thirumalai <kiran@scalex86.org>
302 ---------------------------
304 What: CONFIG_THERMAL_HWMON
305 When: January 2009
306 Why: This option was introduced just to allow older lm-sensors userspace
307 to keep working over the upgrade to 2.6.26. At the scheduled time of
308 removal fixed lm-sensors (2.x or 3.x) should be readily available.
309 Who: Rene Herman <rene.herman@gmail.com>
311 ---------------------------
313 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
314 (in net/core/net-sysfs.c)
315 When: After the only user (hal) has seen a release with the patches
316 for enough time, probably some time in 2010.
317 Why: Over 1K .text/.data size reduction, data is available in other
318 ways (ioctls)
319 Who: Johannes Berg <johannes@sipsolutions.net>
321 ---------------------------
323 What: sysfs ui for changing p4-clockmod parameters
324 When: September 2009
325 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
326 e088e4c9cdb618675874becb91b2fd581ee707e6.
327 Removal is subject to fixing any remaining bugs in ACPI which may
328 cause the thermal throttling not to happen at the right time.
329 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
331 -----------------------------
333 What: __do_IRQ all in one fits nothing interrupt handler
334 When: 2.6.32
335 Why: __do_IRQ was kept for easy migration to the type flow handlers.
336 More than two years of migration time is enough.
337 Who: Thomas Gleixner <tglx@linutronix.de>
339 -----------------------------
341 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
342 When: 2011
343 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
344 represent a machine's physical PCI slots. The change in semantics
345 had userspace implications, as the hotplug core no longer allowed
346 drivers to create multiple sysfs files per physical slot (required
347 for multi-function devices, e.g.). fakephp was seen as a developer's
348 tool only, and its interface changed. Too late, we learned that
349 there were some users of the fakephp interface.
351 In 2.6.30, the original fakephp interface was restored. At the same
352 time, the PCI core gained the ability that fakephp provided, namely
353 function-level hot-remove and hot-add.
355 Since the PCI core now provides the same functionality, exposed in:
357 /sys/bus/pci/rescan
358 /sys/bus/pci/devices/.../remove
359 /sys/bus/pci/devices/.../rescan
361 there is no functional reason to maintain fakephp as well.
363 We will keep the existing module so that 'modprobe fakephp' will
364 present the old /sys/bus/pci/slots/... interface for compatibility,
365 but users are urged to migrate their applications to the API above.
367 After a reasonable transition period, we will remove the legacy
368 fakephp interface.
369 Who: Alex Chiang <achiang@hp.com>
371 ---------------------------
373 What: CONFIG_RFKILL_INPUT
374 When: 2.6.33
375 Why: Should be implemented in userspace, policy daemon.
376 Who: Johannes Berg <johannes@sipsolutions.net>
378 ----------------------------
380 What: sound-slot/service-* module aliases and related clutters in
381 sound/sound_core.c
382 When: August 2010
383 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
384 (14) and requests modules using custom sound-slot/service-*
385 module aliases. The only benefit of doing this is allowing
386 use of custom module aliases which might as well be considered
387 a bug at this point. This preemptive claiming prevents
388 alternative OSS implementations.
390 Till the feature is removed, the kernel will be requesting
391 both sound-slot/service-* and the standard char-major-* module
392 aliases and allow turning off the pre-claiming selectively via
393 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
394 kernel parameter.
396 After the transition phase is complete, both the custom module
397 aliases and switches to disable it will go away. This removal
398 will also allow making ALSA OSS emulation independent of
399 sound_core. The dependency will be broken then too.
400 Who: Tejun Heo <tj@kernel.org>
402 ----------------------------
404 What: Support for lcd_switch and display_get in asus-laptop driver
405 When: March 2010
406 Why: These two features use non-standard interfaces. There are the
407 only features that really need multiple path to guess what's
408 the right method name on a specific laptop.
410 Removing them will allow to remove a lot of code an significantly
411 clean the drivers.
413 This will affect the backlight code which won't be able to know
414 if the backlight is on or off. The platform display file will also be
415 write only (like the one in eeepc-laptop).
417 This should'nt affect a lot of user because they usually know
418 when their display is on or off.
420 Who: Corentin Chary <corentin.chary@gmail.com>
422 ----------------------------
424 What: sysfs-class-rfkill state file
425 When: Feb 2014
426 Files: net/rfkill/core.c
427 Why: Documented as obsolete since Feb 2010. This file is limited to 3
428 states while the rfkill drivers can have 4 states.
429 Who: anybody or Florian Mickler <florian@mickler.org>
431 ----------------------------
433 What: sysfs-class-rfkill claim file
434 When: Feb 2012
435 Files: net/rfkill/core.c
436 Why: It is not possible to claim an rfkill driver since 2007. This is
437 Documented as obsolete since Feb 2010.
438 Who: anybody or Florian Mickler <florian@mickler.org>
440 ----------------------------
442 What: capifs
443 When: February 2011
444 Files: drivers/isdn/capi/capifs.*
445 Why: udev fully replaces this special file system that only contains CAPI
446 NCCI TTY device nodes. User space (pppdcapiplugin) works without
447 noticing the difference.
448 Who: Jan Kiszka <jan.kiszka@web.de>
450 ----------------------------
452 What: KVM paravirt mmu host support
453 When: January 2011
454 Why: The paravirt mmu host support is slower than non-paravirt mmu, both
455 on newer and older hardware. It is already not exposed to the guest,
456 and kept only for live migration purposes.
457 Who: Avi Kivity <avi@redhat.com>
459 ----------------------------
461 What: iwlwifi 50XX module parameters
462 When: 2.6.40
463 Why: The "..50" modules parameters were used to configure 5000 series and
464 up devices; different set of module parameters also available for 4965
465 with same functionalities. Consolidate both set into single place
466 in drivers/net/wireless/iwlwifi/iwl-agn.c
468 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
470 ----------------------------
472 What: iwl4965 alias support
473 When: 2.6.40
474 Why: Internal alias support has been present in module-init-tools for some
475 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
476 with no impact.
478 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
480 ---------------------------
482 What: xt_NOTRACK
483 Files: net/netfilter/xt_NOTRACK.c
484 When: April 2011
485 Why: Superseded by xt_CT
486 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
488 ----------------------------
490 What: IRQF_DISABLED
491 When: 2.6.36
492 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
493 Who: Thomas Gleixner <tglx@linutronix.de>
495 ----------------------------
497 What: The acpi_sleep=s4_nonvs command line option
498 When: 2.6.37
499 Files: arch/x86/kernel/acpi/sleep.c
500 Why: superseded by acpi_sleep=nonvs
501 Who: Rafael J. Wysocki <rjw@sisk.pl>
503 ----------------------------
505 What: PCI DMA unmap state API
506 When: August 2012
507 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
508 with DMA unmap state API (DMA unmap state API can be used for
509 any bus).
510 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
512 ----------------------------
514 What: DMA_xxBIT_MASK macros
515 When: Jun 2011
516 Why: DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros.
517 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
519 ----------------------------
521 What: namespace cgroup (ns_cgroup)
522 When: 2.6.38
523 Why: The ns_cgroup leads to some problems:
524 * cgroup creation is out-of-control
525 * cgroup name can conflict when pids are looping
526 * it is not possible to have a single process handling
527 a lot of namespaces without falling in a exponential creation time
528 * we may want to create a namespace without creating a cgroup
530 The ns_cgroup is replaced by a compatibility flag 'clone_children',
531 where a newly created cgroup will copy the parent cgroup values.
532 The userspace has to manually create a cgroup and add a task to
533 the 'tasks' file.
534 Who: Daniel Lezcano <daniel.lezcano@free.fr>
536 ----------------------------
538 What: iwlwifi disable_hw_scan module parameters
539 When: 2.6.40
540 Why: Hareware scan is the prefer method for iwlwifi devices for
541 scanning operation. Remove software scan support for all the
542 iwlwifi devices.
544 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
546 ----------------------------
548 What: access to nfsd auth cache through sys_nfsservctl or '.' files
549 in the 'nfsd' filesystem.
550 When: 2.6.40
551 Why: This is a legacy interface which have been replaced by a more
552 dynamic cache. Continuing to maintain this interface is an
553 unnecessary burden.
554 Who: NeilBrown <neilb@suse.de>
556 ----------------------------
558 What: i2c_adapter.id
559 When: June 2011
560 Why: This field is deprecated. I2C device drivers shouldn't change their
561 behavior based on the underlying I2C adapter. Instead, the I2C
562 adapter driver should instantiate the I2C devices and provide the
563 needed platform-specific information.
564 Who: Jean Delvare <khali@linux-fr.org>
566 ----------------------------
568 What: cancel_rearming_delayed_work[queue]()
569 When: 2.6.39
571 Why: The functions have been superceded by cancel_delayed_work_sync()
572 quite some time ago. The conversion is trivial and there is no
573 in-kernel user left.
574 Who: Tejun Heo <tj@kernel.org>
576 ----------------------------