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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. The suggested deprecation period is 3 releases.
6
7 ---------------------------
8
9 What: ddebug_query="query" boot cmdline param
10 When: v3.8
11 Why: obsoleted by dyndbg="query" and module.dyndbg="query"
12 Who: Jim Cromie <jim.cromie@gmail.com>, Jason Baron <jbaron@redhat.com>
13
14 ---------------------------
15
16 What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
17 When: 2012
18 Why: This optional sub-feature of APM is of dubious reliability,
19 and ancient APM laptops are likely better served by calling HLT.
20 Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
21 the pm_idle function pointer to modules.
22 Who: Len Brown <len.brown@intel.com>
23
24 ----------------------------
25
26 What: x86_32 "no-hlt" cmdline param
27 When: 2012
28 Why: remove a branch from idle path, simplify code used by everybody.
29 This option disabled the use of HLT in idle and machine_halt()
30 for hardware that was flakey 15-years ago. Today we have
31 "idle=poll" that removed HLT from idle, and so if such a machine
32 is still running the upstream kernel, "idle=poll" is likely sufficient.
33 Who: Len Brown <len.brown@intel.com>
34
35 ----------------------------
36
37 What: x86 "idle=mwait" cmdline param
38 When: 2012
39 Why: simplify x86 idle code
40 Who: Len Brown <len.brown@intel.com>
41
42 ----------------------------
43
44 What: PRISM54
45 When: 2.6.34
46
47 Why: prism54 FullMAC PCI / Cardbus devices used to be supported only by the
48 prism54 wireless driver. After Intersil stopped selling these
49 devices in preference for the newer more flexible SoftMAC devices
50 a SoftMAC device driver was required and prism54 did not support
51 them. The p54pci driver now exists and has been present in the kernel for
52 a while. This driver supports both SoftMAC devices and FullMAC devices.
53 The main difference between these devices was the amount of memory which
54 could be used for the firmware. The SoftMAC devices support a smaller
55 amount of memory. Because of this the SoftMAC firmware fits into FullMAC
56 devices's memory. p54pci supports not only PCI / Cardbus but also USB
57 and SPI. Since p54pci supports all devices prism54 supports
58 you will have a conflict. I'm not quite sure how distributions are
59 handling this conflict right now. prism54 was kept around due to
60 claims users may experience issues when using the SoftMAC driver.
61 Time has passed users have not reported issues. If you use prism54
62 and for whatever reason you cannot use p54pci please let us know!
63 E-mail us at: linux-wireless@vger.kernel.org
64
65 For more information see the p54 wiki page:
66
67 http://wireless.kernel.org/en/users/Drivers/p54
68
69 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
70
71 ---------------------------
72
73 What: IRQF_SAMPLE_RANDOM
74 Check: IRQF_SAMPLE_RANDOM
75 When: July 2009
76
77 Why: Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
78 sources in the kernel's current entropy model. To resolve this, every
79 input point to the kernel's entropy pool needs to better document the
80 type of entropy source it actually is. This will be replaced with
81 additional add_*_randomness functions in drivers/char/random.c
82
83 Who: Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
84
85 ---------------------------
86
87 What: The ieee80211_regdom module parameter
88 When: March 2010 / desktop catchup
89
90 Why: This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
91 and currently serves as an option for users to define an
92 ISO / IEC 3166 alpha2 code for the country they are currently
93 present in. Although there are userspace API replacements for this
94 through nl80211 distributions haven't yet caught up with implementing
95 decent alternatives through standard GUIs. Although available as an
96 option through iw or wpa_supplicant its just a matter of time before
97 distributions pick up good GUI options for this. The ideal solution
98 would actually consist of intelligent designs which would do this for
99 the user automatically even when travelling through different countries.
100 Until then we leave this module parameter as a compromise.
101
102 When userspace improves with reasonable widely-available alternatives for
103 this we will no longer need this module parameter. This entry hopes that
104 by the super-futuristically looking date of "March 2010" we will have
105 such replacements widely available.
106
107 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
108
109 ---------------------------
110
111 What: dev->power.power_state
112 When: July 2007
113 Why: Broken design for runtime control over driver power states, confusing
114 driver-internal runtime power management with: mechanisms to support
115 system-wide sleep state transitions; event codes that distinguish
116 different phases of swsusp "sleep" transitions; and userspace policy
117 inputs. This framework was never widely used, and most attempts to
118 use it were broken. Drivers should instead be exposing domain-specific
119 interfaces either to kernel or to userspace.
120 Who: Pavel Machek <pavel@ucw.cz>
121
122 ---------------------------
123
124 What: /proc/<pid>/oom_adj
125 When: August 2012
126 Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
127 badness heuristic used to determine which task to kill when the kernel
128 is out of memory.
129
130 The badness heuristic has since been rewritten since the introduction of
131 this tunable such that its meaning is deprecated. The value was
132 implemented as a bitshift on a score generated by the badness()
133 function that did not have any precise units of measure. With the
134 rewrite, the score is given as a proportion of available memory to the
135 task allocating pages, so using a bitshift which grows the score
136 exponentially is, thus, impossible to tune with fine granularity.
137
138 A much more powerful interface, /proc/<pid>/oom_score_adj, was
139 introduced with the oom killer rewrite that allows users to increase or
140 decrease the badness score linearly. This interface will replace
141 /proc/<pid>/oom_adj.
142
143 A warning will be emitted to the kernel log if an application uses this
144 deprecated interface. After it is printed once, future warnings will be
145 suppressed until the kernel is rebooted.
146
147 ---------------------------
148
149 What: remove EXPORT_SYMBOL(kernel_thread)
150 When: August 2006
151 Files: arch/*/kernel/*_ksyms.c
152 Check: kernel_thread
153 Why: kernel_thread is a low-level implementation detail. Drivers should
154 use the <linux/kthread.h> API instead which shields them from
155 implementation details and provides a higherlevel interface that
156 prevents bugs and code duplication
157 Who: Christoph Hellwig <hch@lst.de>
158
159 ---------------------------
160
161 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
162 (temporary transition config option provided until then)
163 The transition config option will also be removed at the same time.
164 When: before 2.6.19
165 Why: Unused symbols are both increasing the size of the kernel binary
166 and are often a sign of "wrong API"
167 Who: Arjan van de Ven <arjan@linux.intel.com>
168
169 ---------------------------
170
171 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
172 When: October 2008
173 Why: The stacking of class devices makes these values misleading and
174 inconsistent.
175 Class devices should not carry any of these properties, and bus
176 devices have SUBSYTEM and DRIVER as a replacement.
177 Who: Kay Sievers <kay.sievers@suse.de>
178
179 ---------------------------
180
181 What: ACPI procfs interface
182 When: July 2008
183 Why: ACPI sysfs conversion should be finished by January 2008.
184 ACPI procfs interface will be removed in July 2008 so that
185 there is enough time for the user space to catch up.
186 Who: Zhang Rui <rui.zhang@intel.com>
187
188 ---------------------------
189
190 What: CONFIG_ACPI_PROCFS_POWER
191 When: 2.6.39
192 Why: sysfs I/F for ACPI power devices, including AC and Battery,
193 has been working in upstream kernel since 2.6.24, Sep 2007.
194 In 2.6.37, we make the sysfs I/F always built in and this option
195 disabled by default.
196 Remove this option and the ACPI power procfs interface in 2.6.39.
197 Who: Zhang Rui <rui.zhang@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: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
220 When: February 2010
221 Why: All callers should use explicit gpio_request()/gpio_free().
222 The autorequest mechanism in gpiolib was provided mostly as a
223 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
224 Those users have now largely migrated. Platforms implementing
225 the GPIO interfaces without using gpiolib will see no changes.
226 Who: David Brownell <dbrownell@users.sourceforge.net>
227 ---------------------------
228
229 What: b43 support for firmware revision < 410
230 When: The schedule was July 2008, but it was decided that we are going to keep the
231 code as long as there are no major maintanance headaches.
232 So it _could_ be removed _any_ time now, if it conflicts with something new.
233 Why: The support code for the old firmware hurts code readability/maintainability
234 and slightly hurts runtime performance. Bugfixes for the old firmware
235 are not provided by Broadcom anymore.
236 Who: Michael Buesch <m@bues.ch>
237
238 ---------------------------
239
240 What: Ability for non root users to shm_get hugetlb pages based on mlock
241 resource limits
242 When: 2.6.31
243 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
244 have CAP_IPC_LOCK to be able to allocate shm segments backed by
245 huge pages. The mlock based rlimit check to allow shm hugetlb is
246 inconsistent with mmap based allocations. Hence it is being
247 deprecated.
248 Who: Ravikiran Thirumalai <kiran@scalex86.org>
249
250 ---------------------------
251
252 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
253 (in net/core/net-sysfs.c)
254 When: 3.5
255 Why: Over 1K .text/.data size reduction, data is available in other
256 ways (ioctls)
257 Who: Johannes Berg <johannes@sipsolutions.net>
258
259 ---------------------------
260
261 What: sysfs ui for changing p4-clockmod parameters
262 When: September 2009
263 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
264 e088e4c9cdb618675874becb91b2fd581ee707e6.
265 Removal is subject to fixing any remaining bugs in ACPI which may
266 cause the thermal throttling not to happen at the right time.
267 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
268
269 -----------------------------
270
271 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
272 When: 2011
273 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
274 represent a machine's physical PCI slots. The change in semantics
275 had userspace implications, as the hotplug core no longer allowed
276 drivers to create multiple sysfs files per physical slot (required
277 for multi-function devices, e.g.). fakephp was seen as a developer's
278 tool only, and its interface changed. Too late, we learned that
279 there were some users of the fakephp interface.
280
281 In 2.6.30, the original fakephp interface was restored. At the same
282 time, the PCI core gained the ability that fakephp provided, namely
283 function-level hot-remove and hot-add.
284
285 Since the PCI core now provides the same functionality, exposed in:
286
287 /sys/bus/pci/rescan
288 /sys/bus/pci/devices/.../remove
289 /sys/bus/pci/devices/.../rescan
290
291 there is no functional reason to maintain fakephp as well.
292
293 We will keep the existing module so that 'modprobe fakephp' will
294 present the old /sys/bus/pci/slots/... interface for compatibility,
295 but users are urged to migrate their applications to the API above.
296
297 After a reasonable transition period, we will remove the legacy
298 fakephp interface.
299 Who: Alex Chiang <achiang@hp.com>
300
301 ---------------------------
302
303 What: CONFIG_RFKILL_INPUT
304 When: 2.6.33
305 Why: Should be implemented in userspace, policy daemon.
306 Who: Johannes Berg <johannes@sipsolutions.net>
307
308 ----------------------------
309
310 What: sound-slot/service-* module aliases and related clutters in
311 sound/sound_core.c
312 When: August 2010
313 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
314 (14) and requests modules using custom sound-slot/service-*
315 module aliases. The only benefit of doing this is allowing
316 use of custom module aliases which might as well be considered
317 a bug at this point. This preemptive claiming prevents
318 alternative OSS implementations.
319
320 Till the feature is removed, the kernel will be requesting
321 both sound-slot/service-* and the standard char-major-* module
322 aliases and allow turning off the pre-claiming selectively via
323 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
324 kernel parameter.
325
326 After the transition phase is complete, both the custom module
327 aliases and switches to disable it will go away. This removal
328 will also allow making ALSA OSS emulation independent of
329 sound_core. The dependency will be broken then too.
330 Who: Tejun Heo <tj@kernel.org>
331
332 ----------------------------
333
334 What: sysfs-class-rfkill state file
335 When: Feb 2014
336 Files: net/rfkill/core.c
337 Why: Documented as obsolete since Feb 2010. This file is limited to 3
338 states while the rfkill drivers can have 4 states.
339 Who: anybody or Florian Mickler <florian@mickler.org>
340
341 ----------------------------
342
343 What: sysfs-class-rfkill claim file
344 When: Feb 2012
345 Files: net/rfkill/core.c
346 Why: It is not possible to claim an rfkill driver since 2007. This is
347 Documented as obsolete since Feb 2010.
348 Who: anybody or Florian Mickler <florian@mickler.org>
349
350 ----------------------------
351
352 What: iwlwifi 50XX module parameters
353 When: 3.0
354 Why: The "..50" modules parameters were used to configure 5000 series and
355 up devices; different set of module parameters also available for 4965
356 with same functionalities. Consolidate both set into single place
357 in drivers/net/wireless/iwlwifi/iwl-agn.c
358
359 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
360
361 ----------------------------
362
363 What: iwl4965 alias support
364 When: 3.0
365 Why: Internal alias support has been present in module-init-tools for some
366 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
367 with no impact.
368
369 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
370
371 ---------------------------
372
373 What: xt_NOTRACK
374 Files: net/netfilter/xt_NOTRACK.c
375 When: April 2011
376 Why: Superseded by xt_CT
377 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
378
379 ----------------------------
380
381 What: IRQF_DISABLED
382 When: 2.6.36
383 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
384 Who: Thomas Gleixner <tglx@linutronix.de>
385
386 ----------------------------
387
388 What: PCI DMA unmap state API
389 When: August 2012
390 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
391 with DMA unmap state API (DMA unmap state API can be used for
392 any bus).
393 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
394
395 ----------------------------
396
397 What: iwlwifi disable_hw_scan module parameters
398 When: 3.0
399 Why: Hareware scan is the prefer method for iwlwifi devices for
400 scanning operation. Remove software scan support for all the
401 iwlwifi devices.
402
403 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
404
405 ----------------------------
406
407 What: Legacy, non-standard chassis intrusion detection interface.
408 When: June 2011
409 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
410 legacy interfaces for chassis intrusion detection. A standard
411 interface has been added to each driver, so the legacy interface
412 can be removed.
413 Who: Jean Delvare <khali@linux-fr.org>
414
415 ----------------------------
416
417 What: xt_connlimit rev 0
418 When: 2012
419 Who: Jan Engelhardt <jengelh@medozas.de>
420 Files: net/netfilter/xt_connlimit.c
421
422 ----------------------------
423
424 What: ipt_addrtype match include file
425 When: 2012
426 Why: superseded by xt_addrtype
427 Who: Florian Westphal <fw@strlen.de>
428 Files: include/linux/netfilter_ipv4/ipt_addrtype.h
429
430 ----------------------------
431
432 What: i2c_driver.attach_adapter
433 i2c_driver.detach_adapter
434 When: September 2011
435 Why: These legacy callbacks should no longer be used as i2c-core offers
436 a variety of preferable alternative ways to instantiate I2C devices.
437 Who: Jean Delvare <khali@linux-fr.org>
438
439 ----------------------------
440
441 What: Opening a radio device node will no longer automatically switch the
442 tuner mode from tv to radio.
443 When: 3.3
444 Why: Just opening a V4L device should not change the state of the hardware
445 like that. It's very unexpected and against the V4L spec. Instead, you
446 switch to radio mode by calling VIDIOC_S_FREQUENCY. This is the second
447 and last step of the move to consistent handling of tv and radio tuners.
448 Who: Hans Verkuil <hans.verkuil@cisco.com>
449
450 ----------------------------
451
452 What: g_file_storage driver
453 When: 3.8
454 Why: This driver has been superseded by g_mass_storage.
455 Who: Alan Stern <stern@rowland.harvard.edu>
456
457 ----------------------------
458
459 What: threeg and interface sysfs files in /sys/devices/platform/acer-wmi
460 When: 2012
461 Why: In 3.0, we can now autodetect internal 3G device and already have
462 the threeg rfkill device. So, we plan to remove threeg sysfs support
463 for it's no longer necessary.
464
465 We also plan to remove interface sysfs file that exposed which ACPI-WMI
466 interface that was used by acer-wmi driver. It will replaced by
467 information log when acer-wmi initial.
468 Who: Lee, Chun-Yi <jlee@novell.com>
469
470 ---------------------------
471
472 What: /sys/devices/platform/_UDC_/udc/_UDC_/is_dualspeed file and
473 is_dualspeed line in /sys/devices/platform/ci13xxx_*/udc/device file.
474 When: 3.8
475 Why: The is_dualspeed file is superseded by maximum_speed in the same
476 directory and is_dualspeed line in device file is superseded by
477 max_speed line in the same file.
478
479 The maximum_speed/max_speed specifies maximum speed supported by UDC.
480 To check if dualspeeed is supported, check if the value is >= 3.
481 Various possible speeds are defined in <linux/usb/ch9.h>.
482 Who: Michal Nazarewicz <mina86@mina86.com>
483
484 ----------------------------
485
486 What: The XFS nodelaylog mount option
487 When: 3.3
488 Why: The delaylog mode that has been the default since 2.6.39 has proven
489 stable, and the old code is in the way of additional improvements in
490 the log code.
491 Who: Christoph Hellwig <hch@lst.de>
492
493 ----------------------------
494
495 What: iwlagn alias support
496 When: 3.5
497 Why: The iwlagn module has been renamed iwlwifi. The alias will be around
498 for backward compatibility for several cycles and then dropped.
499 Who: Don Fry <donald.h.fry@intel.com>
500
501 ----------------------------
502
503 What: pci_scan_bus_parented()
504 When: 3.5
505 Why: The pci_scan_bus_parented() interface creates a new root bus. The
506 bus is created with default resources (ioport_resource and
507 iomem_resource) that are always wrong, so we rely on arch code to
508 correct them later. Callers of pci_scan_bus_parented() should
509 convert to using pci_scan_root_bus() so they can supply a list of
510 bus resources when the bus is created.
511 Who: Bjorn Helgaas <bhelgaas@google.com>
512
513 ----------------------------
514
515 What: Low Performance USB Block driver ("CONFIG_BLK_DEV_UB")
516 When: 3.6
517 Why: This driver provides support for USB storage devices like "USB
518 sticks". As of now, it is deactivated in Debian, Fedora and
519 Ubuntu. All current users can switch over to usb-storage
520 (CONFIG_USB_STORAGE) which only drawback is the additional SCSI
521 stack.
522 Who: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
523
524 ----------------------------
525
526 What: kmap_atomic(page, km_type)
527 When: 3.5
528 Why: The old kmap_atomic() with two arguments is deprecated, we only
529 keep it for backward compatibility for few cycles and then drop it.
530 Who: Cong Wang <amwang@redhat.com>
531
532 ----------------------------
533
534 What: get_robust_list syscall
535 When: 2013
536 Why: There appear to be no production users of the get_robust_list syscall,
537 and it runs the risk of leaking address locations, allowing the bypass
538 of ASLR. It was only ever intended for debugging, so it should be
539 removed.
540 Who: Kees Cook <keescook@chromium.org>
541
542 ----------------------------
543
544 What: Removing the pn544 raw driver.
545 When: 3.6
546 Why: With the introduction of the NFC HCI and SHDL kernel layers, pn544.c
547 is being replaced by pn544_hci.c which is accessible through the netlink
548 and socket NFC APIs. Moreover, pn544.c is outdated and does not seem to
549 work properly with the latest Android stacks.
550 Having 2 drivers for the same hardware is confusing and as such we
551 should only keep the one following the kernel NFC APIs.
552 Who: Samuel Ortiz <sameo@linux.intel.com>
553
554 ----------------------------
555
556 What: setitimer accepts user NULL pointer (value)
557 When: 3.6
558 Why: setitimer is not returning -EFAULT if user pointer is NULL. This
559 violates the spec.
560 Who: Sasikantha Babu <sasikanth.v19@gmail.com>
561
562 ----------------------------
563
564 What: remove bogus DV presets V4L2_DV_1080I29_97, V4L2_DV_1080I30 and
565 V4L2_DV_1080I25
566 When: 3.6
567 Why: These HDTV formats do not exist and were added by a confused mind
568 (that was me, to be precise...)
569 Who: Hans Verkuil <hans.verkuil@cisco.com>
570
571 ----------------------------
572
573 What: V4L2_CID_HCENTER, V4L2_CID_VCENTER V4L2 controls
574 When: 3.7
575 Why: The V4L2_CID_VCENTER, V4L2_CID_HCENTER controls have been deprecated
576 for about 4 years and they are not used by any mainline driver.
577 There are newer controls (V4L2_CID_PAN*, V4L2_CID_TILT*) that provide
578 similar functionality.
579 Who: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
580
581 ----------------------------
582
583 What: cgroup option updates via remount
584 When: March 2013
585 Why: Remount currently allows changing bound subsystems and
586 release_agent. Rebinding is hardly useful as it only works
587 when the hierarchy is empty and release_agent itself should be
588 replaced with conventional fsnotify.
589
590 ----------------------------
591
592 What: KVM debugfs statistics
593 When: 2013
594 Why: KVM tracepoints provide mostly equivalent information in a much more
595 flexible fashion.
596
597 ----------------------------
598
599 What: at91-mci driver ("CONFIG_MMC_AT91")
600 When: 3.7
601 Why: There are two mci drivers: at91-mci and atmel-mci. The PDC support
602 was added to atmel-mci as a first step to support more chips.
603 Then at91-mci was kept only for old IP versions (on at91rm9200 and
604 at91sam9261). The support of these IP versions has just been added
605 to atmel-mci, so atmel-mci can be used for all chips.
606 Who: Ludovic Desroches <ludovic.desroches@atmel.com>
607
608 ----------------------------
609
610 What: net/wanrouter/
611 When: June 2013
612 Why: Unsupported/unmaintained/unused since 2.6
613
614 ----------------------------