| blob | b1c921c27519a0953591b6a64159e46856e7558d |
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: x86 floppy disable_hlt
10 When: 2012
11 Why: ancient workaround of dubious utility clutters the
12 code used by everybody else.
13 Who: Len Brown <len.brown@intel.com>
15 ---------------------------
17 What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
18 When: 2012
19 Why: This optional sub-feature of APM is of dubious reliability,
20 and ancient APM laptops are likely better served by calling HLT.
21 Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
22 the pm_idle function pointer to modules.
23 Who: Len Brown <len.brown@intel.com>
25 ----------------------------
27 What: x86_32 "no-hlt" cmdline param
28 When: 2012
29 Why: remove a branch from idle path, simplify code used by everybody.
30 This option disabled the use of HLT in idle and machine_halt()
31 for hardware that was flakey 15-years ago. Today we have
32 "idle=poll" that removed HLT from idle, and so if such a machine
33 is still running the upstream kernel, "idle=poll" is likely sufficient.
34 Who: Len Brown <len.brown@intel.com>
36 ----------------------------
38 What: x86 "idle=mwait" cmdline param
39 When: 2012
40 Why: simplify x86 idle code
41 Who: Len Brown <len.brown@intel.com>
43 ----------------------------
45 What: PRISM54
46 When: 2.6.34
48 Why: prism54 FullMAC PCI / Cardbus devices used to be supported only by the
49 prism54 wireless driver. After Intersil stopped selling these
50 devices in preference for the newer more flexible SoftMAC devices
51 a SoftMAC device driver was required and prism54 did not support
52 them. The p54pci driver now exists and has been present in the kernel for
53 a while. This driver supports both SoftMAC devices and FullMAC devices.
54 The main difference between these devices was the amount of memory which
55 could be used for the firmware. The SoftMAC devices support a smaller
56 amount of memory. Because of this the SoftMAC firmware fits into FullMAC
57 devices's memory. p54pci supports not only PCI / Cardbus but also USB
58 and SPI. Since p54pci supports all devices prism54 supports
59 you will have a conflict. I'm not quite sure how distributions are
60 handling this conflict right now. prism54 was kept around due to
61 claims users may experience issues when using the SoftMAC driver.
62 Time has passed users have not reported issues. If you use prism54
63 and for whatever reason you cannot use p54pci please let us know!
64 E-mail us at: linux-wireless@vger.kernel.org
66 For more information see the p54 wiki page:
68 http://wireless.kernel.org/en/users/Drivers/p54
70 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
72 ---------------------------
74 What: IRQF_SAMPLE_RANDOM
75 Check: IRQF_SAMPLE_RANDOM
76 When: July 2009
78 Why: Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
79 sources in the kernel's current entropy model. To resolve this, every
80 input point to the kernel's entropy pool needs to better document the
81 type of entropy source it actually is. This will be replaced with
82 additional add_*_randomness functions in drivers/char/random.c
84 Who: Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
86 ---------------------------
88 What: Deprecated snapshot ioctls
89 When: 2.6.36
91 Why: The ioctls in kernel/power/user.c were marked as deprecated long time
92 ago. Now they notify users about that so that they need to replace
93 their userspace. After some more time, remove them completely.
95 Who: Jiri Slaby <jirislaby@gmail.com>
97 ---------------------------
99 What: The ieee80211_regdom module parameter
100 When: March 2010 / desktop catchup
102 Why: This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
103 and currently serves as an option for users to define an
104 ISO / IEC 3166 alpha2 code for the country they are currently
105 present in. Although there are userspace API replacements for this
106 through nl80211 distributions haven't yet caught up with implementing
107 decent alternatives through standard GUIs. Although available as an
108 option through iw or wpa_supplicant its just a matter of time before
109 distributions pick up good GUI options for this. The ideal solution
110 would actually consist of intelligent designs which would do this for
111 the user automatically even when travelling through different countries.
112 Until then we leave this module parameter as a compromise.
114 When userspace improves with reasonable widely-available alternatives for
115 this we will no longer need this module parameter. This entry hopes that
116 by the super-futuristically looking date of "March 2010" we will have
117 such replacements widely available.
119 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
121 ---------------------------
123 What: dev->power.power_state
124 When: July 2007
125 Why: Broken design for runtime control over driver power states, confusing
126 driver-internal runtime power management with: mechanisms to support
127 system-wide sleep state transitions; event codes that distinguish
128 different phases of swsusp "sleep" transitions; and userspace policy
129 inputs. This framework was never widely used, and most attempts to
130 use it were broken. Drivers should instead be exposing domain-specific
131 interfaces either to kernel or to userspace.
132 Who: Pavel Machek <pavel@ucw.cz>
134 ---------------------------
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.
143 Binary sysctls are a long standing source of subtle kernel
144 bugs and security issues.
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.
150 The man page for sysctl(2) documents it as unusable for user
151 space programs.
153 sysctl(2) is not generally ABI compatible to a 32bit user
154 space application on a 64bit and a 32bit kernel.
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.
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.
164 In the mean time individual binary sysctls can be dealt with
165 in a piecewise fashion.
167 Who: Eric Biederman <ebiederm@xmission.com>
169 ---------------------------
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.
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.
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.
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.
194 ---------------------------
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>
208 --------------------------
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>
220 ---------------------------
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>
230 ---------------------------
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>
240 ---------------------------
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>
249 ---------------------------
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 kernel 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>
260 ---------------------------
262 What: /proc/acpi/event
263 When: February 2008
264 Why: /proc/acpi/event has been replaced by events via the input layer
265 and netlink since 2.6.23.
266 Who: Len Brown <len.brown@intel.com>
268 ---------------------------
270 What: i386/x86_64 bzImage symlinks
271 When: April 2010
273 Why: The i386/x86_64 merge provides a symlink to the old bzImage
274 location so not yet updated user space tools, e.g. package
275 scripts, do not break.
276 Who: Thomas Gleixner <tglx@linutronix.de>
278 ---------------------------
280 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
281 When: February 2010
282 Why: All callers should use explicit gpio_request()/gpio_free().
283 The autorequest mechanism in gpiolib was provided mostly as a
284 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
285 Those users have now largely migrated. Platforms implementing
286 the GPIO interfaces without using gpiolib will see no changes.
287 Who: David Brownell <dbrownell@users.sourceforge.net>
288 ---------------------------
290 What: b43 support for firmware revision < 410
291 When: The schedule was July 2008, but it was decided that we are going to keep the
292 code as long as there are no major maintanance headaches.
293 So it _could_ be removed _any_ time now, if it conflicts with something new.
294 Why: The support code for the old firmware hurts code readability/maintainability
295 and slightly hurts runtime performance. Bugfixes for the old firmware
296 are not provided by Broadcom anymore.
297 Who: Michael Buesch <mb@bu3sch.de>
299 ---------------------------
301 What: Ability for non root users to shm_get hugetlb pages based on mlock
302 resource limits
303 When: 2.6.31
304 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
305 have CAP_IPC_LOCK to be able to allocate shm segments backed by
306 huge pages. The mlock based rlimit check to allow shm hugetlb is
307 inconsistent with mmap based allocations. Hence it is being
308 deprecated.
309 Who: Ravikiran Thirumalai <kiran@scalex86.org>
311 ---------------------------
313 What: CONFIG_THERMAL_HWMON
314 When: January 2009
315 Why: This option was introduced just to allow older lm-sensors userspace
316 to keep working over the upgrade to 2.6.26. At the scheduled time of
317 removal fixed lm-sensors (2.x or 3.x) should be readily available.
318 Who: Rene Herman <rene.herman@gmail.com>
320 ---------------------------
322 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
323 (in net/core/net-sysfs.c)
324 When: After the only user (hal) has seen a release with the patches
325 for enough time, probably some time in 2010.
326 Why: Over 1K .text/.data size reduction, data is available in other
327 ways (ioctls)
328 Who: Johannes Berg <johannes@sipsolutions.net>
330 ---------------------------
332 What: sysfs ui for changing p4-clockmod parameters
333 When: September 2009
334 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
335 e088e4c9cdb618675874becb91b2fd581ee707e6.
336 Removal is subject to fixing any remaining bugs in ACPI which may
337 cause the thermal throttling not to happen at the right time.
338 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
340 -----------------------------
342 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
343 When: 2011
344 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
345 represent a machine's physical PCI slots. The change in semantics
346 had userspace implications, as the hotplug core no longer allowed
347 drivers to create multiple sysfs files per physical slot (required
348 for multi-function devices, e.g.). fakephp was seen as a developer's
349 tool only, and its interface changed. Too late, we learned that
350 there were some users of the fakephp interface.
352 In 2.6.30, the original fakephp interface was restored. At the same
353 time, the PCI core gained the ability that fakephp provided, namely
354 function-level hot-remove and hot-add.
356 Since the PCI core now provides the same functionality, exposed in:
358 /sys/bus/pci/rescan
359 /sys/bus/pci/devices/.../remove
360 /sys/bus/pci/devices/.../rescan
362 there is no functional reason to maintain fakephp as well.
364 We will keep the existing module so that 'modprobe fakephp' will
365 present the old /sys/bus/pci/slots/... interface for compatibility,
366 but users are urged to migrate their applications to the API above.
368 After a reasonable transition period, we will remove the legacy
369 fakephp interface.
370 Who: Alex Chiang <achiang@hp.com>
372 ---------------------------
374 What: CONFIG_RFKILL_INPUT
375 When: 2.6.33
376 Why: Should be implemented in userspace, policy daemon.
377 Who: Johannes Berg <johannes@sipsolutions.net>
379 ----------------------------
381 What: sound-slot/service-* module aliases and related clutters in
382 sound/sound_core.c
383 When: August 2010
384 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
385 (14) and requests modules using custom sound-slot/service-*
386 module aliases. The only benefit of doing this is allowing
387 use of custom module aliases which might as well be considered
388 a bug at this point. This preemptive claiming prevents
389 alternative OSS implementations.
391 Till the feature is removed, the kernel will be requesting
392 both sound-slot/service-* and the standard char-major-* module
393 aliases and allow turning off the pre-claiming selectively via
394 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
395 kernel parameter.
397 After the transition phase is complete, both the custom module
398 aliases and switches to disable it will go away. This removal
399 will also allow making ALSA OSS emulation independent of
400 sound_core. The dependency will be broken then too.
401 Who: Tejun Heo <tj@kernel.org>
403 ----------------------------
405 What: sysfs-class-rfkill state file
406 When: Feb 2014
407 Files: net/rfkill/core.c
408 Why: Documented as obsolete since Feb 2010. This file is limited to 3
409 states while the rfkill drivers can have 4 states.
410 Who: anybody or Florian Mickler <florian@mickler.org>
412 ----------------------------
414 What: sysfs-class-rfkill claim file
415 When: Feb 2012
416 Files: net/rfkill/core.c
417 Why: It is not possible to claim an rfkill driver since 2007. This is
418 Documented as obsolete since Feb 2010.
419 Who: anybody or Florian Mickler <florian@mickler.org>
421 ----------------------------
423 What: KVM paravirt mmu host support
424 When: January 2011
425 Why: The paravirt mmu host support is slower than non-paravirt mmu, both
426 on newer and older hardware. It is already not exposed to the guest,
427 and kept only for live migration purposes.
428 Who: Avi Kivity <avi@redhat.com>
430 ----------------------------
432 What: iwlwifi 50XX module parameters
433 When: 2.6.40
434 Why: The "..50" modules parameters were used to configure 5000 series and
435 up devices; different set of module parameters also available for 4965
436 with same functionalities. Consolidate both set into single place
437 in drivers/net/wireless/iwlwifi/iwl-agn.c
439 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
441 ----------------------------
443 What: iwl4965 alias support
444 When: 2.6.40
445 Why: Internal alias support has been present in module-init-tools for some
446 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
447 with no impact.
449 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
451 ---------------------------
453 What: xt_NOTRACK
454 Files: net/netfilter/xt_NOTRACK.c
455 When: April 2011
456 Why: Superseded by xt_CT
457 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
459 ----------------------------
461 What: IRQF_DISABLED
462 When: 2.6.36
463 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
464 Who: Thomas Gleixner <tglx@linutronix.de>
466 ----------------------------
468 What: PCI DMA unmap state API
469 When: August 2012
470 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
471 with DMA unmap state API (DMA unmap state API can be used for
472 any bus).
473 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
475 ----------------------------
477 What: DMA_xxBIT_MASK macros
478 When: Jun 2011
479 Why: DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros.
480 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
482 ----------------------------
484 What: iwlwifi disable_hw_scan module parameters
485 When: 2.6.40
486 Why: Hareware scan is the prefer method for iwlwifi devices for
487 scanning operation. Remove software scan support for all the
488 iwlwifi devices.
490 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
492 ----------------------------
494 What: access to nfsd auth cache through sys_nfsservctl or '.' files
495 in the 'nfsd' filesystem.
496 When: 2.6.40
497 Why: This is a legacy interface which have been replaced by a more
498 dynamic cache. Continuing to maintain this interface is an
499 unnecessary burden.
500 Who: NeilBrown <neilb@suse.de>
502 ----------------------------
504 What: cancel_rearming_delayed_work[queue]()
505 When: 2.6.39
507 Why: The functions have been superceded by cancel_delayed_work_sync()
508 quite some time ago. The conversion is trivial and there is no
509 in-kernel user left.
510 Who: Tejun Heo <tj@kernel.org>
512 ----------------------------
514 What: Legacy, non-standard chassis intrusion detection interface.
515 When: June 2011
516 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
517 legacy interfaces for chassis intrusion detection. A standard
518 interface has been added to each driver, so the legacy interface
519 can be removed.
520 Who: Jean Delvare <khali@linux-fr.org>
522 ----------------------------
524 What: xt_connlimit rev 0
525 When: 2012
526 Who: Jan Engelhardt <jengelh@medozas.de>
527 Files: net/netfilter/xt_connlimit.c
529 ----------------------------
531 What: noswapaccount kernel command line parameter
532 When: 2.6.40
533 Why: The original implementation of memsw feature enabled by
534 CONFIG_CGROUP_MEM_RES_CTLR_SWAP could be disabled by the noswapaccount
535 kernel parameter (introduced in 2.6.29-rc1). Later on, this decision
536 turned out to be not ideal because we cannot have the feature compiled
537 in and disabled by default and let only interested to enable it
538 (e.g. general distribution kernels might need it). Therefore we have
539 added swapaccount[=0|1] parameter (introduced in 2.6.37) which provides
540 the both possibilities. If we remove noswapaccount we will have
541 less command line parameters with the same functionality and we
542 can also cleanup the parameter handling a bit ().
543 Who: Michal Hocko <mhocko@suse.cz>
545 ----------------------------
547 What: ipt_addrtype match include file
548 When: 2012
549 Why: superseded by xt_addrtype
550 Who: Florian Westphal <fw@strlen.de>
551 Files: include/linux/netfilter_ipv4/ipt_addrtype.h
553 ----------------------------
555 What: i2c_driver.attach_adapter
556 i2c_driver.detach_adapter
557 When: September 2011
558 Why: These legacy callbacks should no longer be used as i2c-core offers
559 a variety of preferable alternative ways to instantiate I2C devices.
560 Who: Jean Delvare <khali@linux-fr.org>
562 ----------------------------
564 What: Support for UVCIOC_CTRL_ADD in the uvcvideo driver
565 When: 2.6.42
566 Why: The information passed to the driver by this ioctl is now queried
567 dynamically from the device.
568 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
570 ----------------------------
572 What: Support for UVCIOC_CTRL_MAP_OLD in the uvcvideo driver
573 When: 2.6.42
574 Why: Used only by applications compiled against older driver versions.
575 Superseded by UVCIOC_CTRL_MAP which supports V4L2 menu controls.
576 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
578 ----------------------------
580 What: Support for UVCIOC_CTRL_GET and UVCIOC_CTRL_SET in the uvcvideo driver
581 When: 2.6.42
582 Why: Superseded by the UVCIOC_CTRL_QUERY ioctl.
583 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
585 ----------------------------
587 What: For VIDIOC_S_FREQUENCY the type field must match the device node's type.
588 If not, return -EINVAL.
589 When: 3.2
590 Why: It makes no sense to switch the tuner to radio mode by calling
591 VIDIOC_S_FREQUENCY on a video node, or to switch the tuner to tv mode by
592 calling VIDIOC_S_FREQUENCY on a radio node. This is the first step of a
593 move to more consistent handling of tv and radio tuners.
594 Who: Hans Verkuil <hans.verkuil@cisco.com>
596 ----------------------------
598 What: Opening a radio device node will no longer automatically switch the
599 tuner mode from tv to radio.
600 When: 3.3
601 Why: Just opening a V4L device should not change the state of the hardware
602 like that. It's very unexpected and against the V4L spec. Instead, you
603 switch to radio mode by calling VIDIOC_S_FREQUENCY. This is the second
604 and last step of the move to consistent handling of tv and radio tuners.
605 Who: Hans Verkuil <hans.verkuil@cisco.com>
607 ----------------------------