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.
7 ---------------------------
9 What: ddebug_query="query" boot cmdline param
11 Why: obsoleted by dyndbg="query" and module.dyndbg="query"
12 Who: Jim Cromie <jim.cromie@gmail.com>, Jason Baron <jbaron@redhat.com>
14 ---------------------------
16 What: /proc/sys/vm/nr_pdflush_threads
18 Why: Since pdflush is deprecated, the interface exported in /proc/sys/vm/
20 Who: Wanpeng Li <liwp@linux.vnet.ibm.com>
22 ---------------------------
24 What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
26 Why: This optional sub-feature of APM is of dubious reliability,
27 and ancient APM laptops are likely better served by calling HLT.
28 Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
29 the pm_idle function pointer to modules.
30 Who: Len Brown <len.brown@intel.com>
32 ----------------------------
34 What: x86_32 "no-hlt" cmdline param
36 Why: remove a branch from idle path, simplify code used by everybody.
37 This option disabled the use of HLT in idle and machine_halt()
38 for hardware that was flakey 15-years ago. Today we have
39 "idle=poll" that removed HLT from idle, and so if such a machine
40 is still running the upstream kernel, "idle=poll" is likely sufficient.
41 Who: Len Brown <len.brown@intel.com>
43 ----------------------------
45 What: x86 "idle=mwait" cmdline param
47 Why: simplify x86 idle code
48 Who: Len Brown <len.brown@intel.com>
50 ----------------------------
55 Why: prism54 FullMAC PCI / Cardbus devices used to be supported only by the
56 prism54 wireless driver. After Intersil stopped selling these
57 devices in preference for the newer more flexible SoftMAC devices
58 a SoftMAC device driver was required and prism54 did not support
59 them. The p54pci driver now exists and has been present in the kernel for
60 a while. This driver supports both SoftMAC devices and FullMAC devices.
61 The main difference between these devices was the amount of memory which
62 could be used for the firmware. The SoftMAC devices support a smaller
63 amount of memory. Because of this the SoftMAC firmware fits into FullMAC
64 devices's memory. p54pci supports not only PCI / Cardbus but also USB
65 and SPI. Since p54pci supports all devices prism54 supports
66 you will have a conflict. I'm not quite sure how distributions are
67 handling this conflict right now. prism54 was kept around due to
68 claims users may experience issues when using the SoftMAC driver.
69 Time has passed users have not reported issues. If you use prism54
70 and for whatever reason you cannot use p54pci please let us know!
71 E-mail us at: linux-wireless@vger.kernel.org
73 For more information see the p54 wiki page:
75 http://wireless.kernel.org/en/users/Drivers/p54
77 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
79 ---------------------------
81 What: The ieee80211_regdom module parameter
82 When: March 2010 / desktop catchup
84 Why: This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
85 and currently serves as an option for users to define an
86 ISO / IEC 3166 alpha2 code for the country they are currently
87 present in. Although there are userspace API replacements for this
88 through nl80211 distributions haven't yet caught up with implementing
89 decent alternatives through standard GUIs. Although available as an
90 option through iw or wpa_supplicant its just a matter of time before
91 distributions pick up good GUI options for this. The ideal solution
92 would actually consist of intelligent designs which would do this for
93 the user automatically even when travelling through different countries.
94 Until then we leave this module parameter as a compromise.
96 When userspace improves with reasonable widely-available alternatives for
97 this we will no longer need this module parameter. This entry hopes that
98 by the super-futuristically looking date of "March 2010" we will have
99 such replacements widely available.
101 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
103 ---------------------------
105 What: dev->power.power_state
107 Why: Broken design for runtime control over driver power states, confusing
108 driver-internal runtime power management with: mechanisms to support
109 system-wide sleep state transitions; event codes that distinguish
110 different phases of swsusp "sleep" transitions; and userspace policy
111 inputs. This framework was never widely used, and most attempts to
112 use it were broken. Drivers should instead be exposing domain-specific
113 interfaces either to kernel or to userspace.
114 Who: Pavel Machek <pavel@ucw.cz>
116 ---------------------------
118 What: /proc/<pid>/oom_adj
120 Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
121 badness heuristic used to determine which task to kill when the kernel
124 The badness heuristic has since been rewritten since the introduction of
125 this tunable such that its meaning is deprecated. The value was
126 implemented as a bitshift on a score generated by the badness()
127 function that did not have any precise units of measure. With the
128 rewrite, the score is given as a proportion of available memory to the
129 task allocating pages, so using a bitshift which grows the score
130 exponentially is, thus, impossible to tune with fine granularity.
132 A much more powerful interface, /proc/<pid>/oom_score_adj, was
133 introduced with the oom killer rewrite that allows users to increase or
134 decrease the badness score linearly. This interface will replace
137 A warning will be emitted to the kernel log if an application uses this
138 deprecated interface. After it is printed once, future warnings will be
139 suppressed until the kernel is rebooted.
141 ---------------------------
143 What: remove EXPORT_SYMBOL(kernel_thread)
145 Files: arch/*/kernel/*_ksyms.c
147 Why: kernel_thread is a low-level implementation detail. Drivers should
148 use the <linux/kthread.h> API instead which shields them from
149 implementation details and provides a higherlevel interface that
150 prevents bugs and code duplication
151 Who: Christoph Hellwig <hch@lst.de>
153 ---------------------------
155 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
156 (temporary transition config option provided until then)
157 The transition config option will also be removed at the same time.
159 Why: Unused symbols are both increasing the size of the kernel binary
160 and are often a sign of "wrong API"
161 Who: Arjan van de Ven <arjan@linux.intel.com>
163 ---------------------------
165 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
167 Why: The stacking of class devices makes these values misleading and
169 Class devices should not carry any of these properties, and bus
170 devices have SUBSYTEM and DRIVER as a replacement.
171 Who: Kay Sievers <kay.sievers@suse.de>
173 ---------------------------
175 What: ACPI procfs interface
177 Why: ACPI sysfs conversion should be finished by January 2008.
178 ACPI procfs interface will be removed in July 2008 so that
179 there is enough time for the user space to catch up.
180 Who: Zhang Rui <rui.zhang@intel.com>
182 ---------------------------
184 What: CONFIG_ACPI_PROCFS_POWER
186 Why: sysfs I/F for ACPI power devices, including AC and Battery,
187 has been working in upstream kernel since 2.6.24, Sep 2007.
188 In 2.6.37, we make the sysfs I/F always built in and this option
190 Remove this option and the ACPI power procfs interface in 2.6.39.
191 Who: Zhang Rui <rui.zhang@intel.com>
193 ---------------------------
195 What: /proc/acpi/event
197 Why: /proc/acpi/event has been replaced by events via the input layer
198 and netlink since 2.6.23.
199 Who: Len Brown <len.brown@intel.com>
201 ---------------------------
203 What: i386/x86_64 bzImage symlinks
206 Why: The i386/x86_64 merge provides a symlink to the old bzImage
207 location so not yet updated user space tools, e.g. package
208 scripts, do not break.
209 Who: Thomas Gleixner <tglx@linutronix.de>
211 ---------------------------
213 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
215 Why: All callers should use explicit gpio_request()/gpio_free().
216 The autorequest mechanism in gpiolib was provided mostly as a
217 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
218 Those users have now largely migrated. Platforms implementing
219 the GPIO interfaces without using gpiolib will see no changes.
220 Who: David Brownell <dbrownell@users.sourceforge.net>
221 ---------------------------
223 What: b43 support for firmware revision < 410
224 When: The schedule was July 2008, but it was decided that we are going to keep the
225 code as long as there are no major maintanance headaches.
226 So it _could_ be removed _any_ time now, if it conflicts with something new.
227 Why: The support code for the old firmware hurts code readability/maintainability
228 and slightly hurts runtime performance. Bugfixes for the old firmware
229 are not provided by Broadcom anymore.
230 Who: Michael Buesch <m@bues.ch>
232 ---------------------------
234 What: Ability for non root users to shm_get hugetlb pages based on mlock
237 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
238 have CAP_IPC_LOCK to be able to allocate shm segments backed by
239 huge pages. The mlock based rlimit check to allow shm hugetlb is
240 inconsistent with mmap based allocations. Hence it is being
242 Who: Ravikiran Thirumalai <kiran@scalex86.org>
244 ---------------------------
246 What: sysfs ui for changing p4-clockmod parameters
248 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
249 e088e4c9cdb618675874becb91b2fd581ee707e6.
250 Removal is subject to fixing any remaining bugs in ACPI which may
251 cause the thermal throttling not to happen at the right time.
252 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
254 -----------------------------
256 What: CONFIG_RFKILL_INPUT
258 Why: Should be implemented in userspace, policy daemon.
259 Who: Johannes Berg <johannes@sipsolutions.net>
261 ----------------------------
263 What: sound-slot/service-* module aliases and related clutters in
266 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
267 (14) and requests modules using custom sound-slot/service-*
268 module aliases. The only benefit of doing this is allowing
269 use of custom module aliases which might as well be considered
270 a bug at this point. This preemptive claiming prevents
271 alternative OSS implementations.
273 Till the feature is removed, the kernel will be requesting
274 both sound-slot/service-* and the standard char-major-* module
275 aliases and allow turning off the pre-claiming selectively via
276 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
279 After the transition phase is complete, both the custom module
280 aliases and switches to disable it will go away. This removal
281 will also allow making ALSA OSS emulation independent of
282 sound_core. The dependency will be broken then too.
283 Who: Tejun Heo <tj@kernel.org>
285 ----------------------------
287 What: sysfs-class-rfkill state file
289 Files: net/rfkill/core.c
290 Why: Documented as obsolete since Feb 2010. This file is limited to 3
291 states while the rfkill drivers can have 4 states.
292 Who: anybody or Florian Mickler <florian@mickler.org>
294 ----------------------------
296 What: sysfs-class-rfkill claim file
298 Files: net/rfkill/core.c
299 Why: It is not possible to claim an rfkill driver since 2007. This is
300 Documented as obsolete since Feb 2010.
301 Who: anybody or Florian Mickler <florian@mickler.org>
303 ----------------------------
305 What: iwlwifi 50XX module parameters
307 Why: The "..50" modules parameters were used to configure 5000 series and
308 up devices; different set of module parameters also available for 4965
309 with same functionalities. Consolidate both set into single place
310 in drivers/net/wireless/iwlwifi/iwl-agn.c
312 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
314 ----------------------------
316 What: iwl4965 alias support
318 Why: Internal alias support has been present in module-init-tools for some
319 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
322 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
324 ---------------------------
327 Files: net/netfilter/xt_NOTRACK.c
329 Why: Superseded by xt_CT
330 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
332 ----------------------------
336 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
337 Who: Thomas Gleixner <tglx@linutronix.de>
339 ----------------------------
341 What: PCI DMA unmap state API
343 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
344 with DMA unmap state API (DMA unmap state API can be used for
346 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
348 ----------------------------
350 What: iwlwifi disable_hw_scan module parameters
352 Why: Hareware scan is the prefer method for iwlwifi devices for
353 scanning operation. Remove software scan support for all the
356 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
358 ----------------------------
360 What: Legacy, non-standard chassis intrusion detection interface.
362 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
363 legacy interfaces for chassis intrusion detection. A standard
364 interface has been added to each driver, so the legacy interface
366 Who: Jean Delvare <khali@linux-fr.org>
368 ----------------------------
370 What: i2c_driver.attach_adapter
371 i2c_driver.detach_adapter
373 Why: These legacy callbacks should no longer be used as i2c-core offers
374 a variety of preferable alternative ways to instantiate I2C devices.
375 Who: Jean Delvare <khali@linux-fr.org>
377 ----------------------------
379 What: Opening a radio device node will no longer automatically switch the
380 tuner mode from tv to radio.
382 Why: Just opening a V4L device should not change the state of the hardware
383 like that. It's very unexpected and against the V4L spec. Instead, you
384 switch to radio mode by calling VIDIOC_S_FREQUENCY. This is the second
385 and last step of the move to consistent handling of tv and radio tuners.
386 Who: Hans Verkuil <hans.verkuil@cisco.com>
388 ----------------------------
390 What: CONFIG_CFG80211_WEXT
391 When: as soon as distributions ship new wireless tools, ie. wpa_supplicant 1.0
392 and NetworkManager/connman/etc. that are able to use nl80211
393 Why: Wireless extensions are deprecated, and userland tools are moving to
394 using nl80211. New drivers are no longer using wireless extensions,
395 and while there might still be old drivers, both new drivers and new
396 userland no longer needs them and they can't be used for an feature
397 developed in the past couple of years. As such, compatibility with
398 wireless extensions in new drivers will be removed.
399 Who: Johannes Berg <johannes@sipsolutions.net>
401 ----------------------------
403 What: g_file_storage driver
405 Why: This driver has been superseded by g_mass_storage.
406 Who: Alan Stern <stern@rowland.harvard.edu>
408 ----------------------------
410 What: threeg and interface sysfs files in /sys/devices/platform/acer-wmi
412 Why: In 3.0, we can now autodetect internal 3G device and already have
413 the threeg rfkill device. So, we plan to remove threeg sysfs support
414 for it's no longer necessary.
416 We also plan to remove interface sysfs file that exposed which ACPI-WMI
417 interface that was used by acer-wmi driver. It will replaced by
418 information log when acer-wmi initial.
419 Who: Lee, Chun-Yi <jlee@novell.com>
421 ---------------------------
423 What: /sys/devices/platform/_UDC_/udc/_UDC_/is_dualspeed file and
424 is_dualspeed line in /sys/devices/platform/ci13xxx_*/udc/device file.
426 Why: The is_dualspeed file is superseded by maximum_speed in the same
427 directory and is_dualspeed line in device file is superseded by
428 max_speed line in the same file.
430 The maximum_speed/max_speed specifies maximum speed supported by UDC.
431 To check if dualspeeed is supported, check if the value is >= 3.
432 Various possible speeds are defined in <linux/usb/ch9.h>.
433 Who: Michal Nazarewicz <mina86@mina86.com>
435 ----------------------------
437 What: The XFS nodelaylog mount option
439 Why: The delaylog mode that has been the default since 2.6.39 has proven
440 stable, and the old code is in the way of additional improvements in
442 Who: Christoph Hellwig <hch@lst.de>
444 ----------------------------
446 What: iwlagn alias support
448 Why: The iwlagn module has been renamed iwlwifi. The alias will be around
449 for backward compatibility for several cycles and then dropped.
450 Who: Don Fry <donald.h.fry@intel.com>
452 ----------------------------
454 What: pci_scan_bus_parented()
456 Why: The pci_scan_bus_parented() interface creates a new root bus. The
457 bus is created with default resources (ioport_resource and
458 iomem_resource) that are always wrong, so we rely on arch code to
459 correct them later. Callers of pci_scan_bus_parented() should
460 convert to using pci_scan_root_bus() so they can supply a list of
461 bus resources when the bus is created.
462 Who: Bjorn Helgaas <bhelgaas@google.com>
464 ----------------------------
466 What: Low Performance USB Block driver ("CONFIG_BLK_DEV_UB")
468 Why: This driver provides support for USB storage devices like "USB
469 sticks". As of now, it is deactivated in Debian, Fedora and
470 Ubuntu. All current users can switch over to usb-storage
471 (CONFIG_USB_STORAGE) which only drawback is the additional SCSI
473 Who: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
475 ----------------------------
477 What: get_robust_list syscall
479 Why: There appear to be no production users of the get_robust_list syscall,
480 and it runs the risk of leaking address locations, allowing the bypass
481 of ASLR. It was only ever intended for debugging, so it should be
483 Who: Kees Cook <keescook@chromium.org>
485 ----------------------------
487 What: Removing the pn544 raw driver.
489 Why: With the introduction of the NFC HCI and SHDL kernel layers, pn544.c
490 is being replaced by pn544_hci.c which is accessible through the netlink
491 and socket NFC APIs. Moreover, pn544.c is outdated and does not seem to
492 work properly with the latest Android stacks.
493 Having 2 drivers for the same hardware is confusing and as such we
494 should only keep the one following the kernel NFC APIs.
495 Who: Samuel Ortiz <sameo@linux.intel.com>
497 ----------------------------
499 What: setitimer accepts user NULL pointer (value)
501 Why: setitimer is not returning -EFAULT if user pointer is NULL. This
503 Who: Sasikantha Babu <sasikanth.v19@gmail.com>
505 ----------------------------
507 What: remove bogus DV presets V4L2_DV_1080I29_97, V4L2_DV_1080I30 and
510 Why: These HDTV formats do not exist and were added by a confused mind
511 (that was me, to be precise...)
512 Who: Hans Verkuil <hans.verkuil@cisco.com>
514 ----------------------------
516 What: V4L2_CID_HCENTER, V4L2_CID_VCENTER V4L2 controls
518 Why: The V4L2_CID_VCENTER, V4L2_CID_HCENTER controls have been deprecated
519 for about 4 years and they are not used by any mainline driver.
520 There are newer controls (V4L2_CID_PAN*, V4L2_CID_TILT*) that provide
521 similar functionality.
522 Who: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
524 ----------------------------
526 What: cgroup option updates via remount
528 Why: Remount currently allows changing bound subsystems and
529 release_agent. Rebinding is hardly useful as it only works
530 when the hierarchy is empty and release_agent itself should be
531 replaced with conventional fsnotify.
533 ----------------------------
535 What: xt_recent rev 0
537 Who: Pablo Neira Ayuso <pablo@netfilter.org>
538 Files: net/netfilter/xt_recent.c
540 ----------------------------
542 What: KVM debugfs statistics
544 Why: KVM tracepoints provide mostly equivalent information in a much more
547 ----------------------------
549 What: at91-mci driver ("CONFIG_MMC_AT91")
551 Why: There are two mci drivers: at91-mci and atmel-mci. The PDC support
552 was added to atmel-mci as a first step to support more chips.
553 Then at91-mci was kept only for old IP versions (on at91rm9200 and
554 at91sam9261). The support of these IP versions has just been added
555 to atmel-mci, so atmel-mci can be used for all chips.
556 Who: Ludovic Desroches <ludovic.desroches@atmel.com>
558 ----------------------------
562 Why: Unsupported/unmaintained/unused since 2.6
564 ----------------------------
566 What: V4L2 selections API target rectangle and flags unification, the
567 following definitions will be removed: V4L2_SEL_TGT_CROP_ACTIVE,
568 V4L2_SEL_TGT_COMPOSE_ACTIVE, V4L2_SUBDEV_SEL_*, V4L2_SUBDEV_SEL_FLAG_*
569 in favor of common V4L2_SEL_TGT_* and V4L2_SEL_FLAG_* definitions.
570 For more details see include/linux/v4l2-common.h.
572 Why: The regular V4L2 selections and the subdev selection API originally
573 defined distinct names for the target rectangles and flags - V4L2_SEL_*
574 and V4L2_SUBDEV_SEL_*. Although, it turned out that the meaning of these
575 target rectangles is virtually identical and the APIs were consolidated
576 to use single set of names - V4L2_SEL_*. This didn't involve any ABI
577 changes. Alias definitions were created for the original ones to avoid
578 any instabilities in the user space interface. After few cycles these
579 backward compatibility definitions will be removed.
580 Who: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
582 ----------------------------
584 What: Using V4L2_CAP_VIDEO_CAPTURE and V4L2_CAP_VIDEO_OUTPUT flags
585 to indicate a V4L2 memory-to-memory device capability
587 Why: New drivers should use new V4L2_CAP_VIDEO_M2M capability flag
588 to indicate a V4L2 video memory-to-memory (M2M) device and
589 applications can now identify a M2M video device by checking
590 for V4L2_CAP_VIDEO_M2M, with VIDIOC_QUERYCAP ioctl. Using ORed
591 V4L2_CAP_VIDEO_CAPTURE and V4L2_CAP_VIDEO_OUTPUT flags for M2M
592 devices is ambiguous and may lead, for example, to identifying
593 a M2M device as a video capture or output device.
594 Who: Sylwester Nawrocki <s.nawrocki@samsung.com>
596 ----------------------------
598 What: OMAP private DMA implementation
600 Why: We have a DMA engine implementation; all users should be updated
601 to use this rather than persisting with the old APIs. The old APIs
602 block merging the old DMA engine implementation into the DMA
604 Who: Russell King <linux@arm.linux.org.uk>,
605 Santosh Shilimkar <santosh.shilimkar@ti.com>
607 ----------------------------