| blob | 709e08e9a222fd9f89a6eb91edf9f5b3326df536 |
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: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
10 When: 2012
11 Why: This optional sub-feature of APM is of dubious reliability,
12 and ancient APM laptops are likely better served by calling HLT.
13 Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
14 the pm_idle function pointer to modules.
15 Who: Len Brown <len.brown@intel.com>
17 ----------------------------
19 What: x86_32 "no-hlt" cmdline param
20 When: 2012
21 Why: remove a branch from idle path, simplify code used by everybody.
22 This option disabled the use of HLT in idle and machine_halt()
23 for hardware that was flakey 15-years ago. Today we have
24 "idle=poll" that removed HLT from idle, and so if such a machine
25 is still running the upstream kernel, "idle=poll" is likely sufficient.
26 Who: Len Brown <len.brown@intel.com>
28 ----------------------------
30 What: x86 "idle=mwait" cmdline param
31 When: 2012
32 Why: simplify x86 idle code
33 Who: Len Brown <len.brown@intel.com>
35 ----------------------------
37 What: PRISM54
38 When: 2.6.34
40 Why: prism54 FullMAC PCI / Cardbus devices used to be supported only by the
41 prism54 wireless driver. After Intersil stopped selling these
42 devices in preference for the newer more flexible SoftMAC devices
43 a SoftMAC device driver was required and prism54 did not support
44 them. The p54pci driver now exists and has been present in the kernel for
45 a while. This driver supports both SoftMAC devices and FullMAC devices.
46 The main difference between these devices was the amount of memory which
47 could be used for the firmware. The SoftMAC devices support a smaller
48 amount of memory. Because of this the SoftMAC firmware fits into FullMAC
49 devices's memory. p54pci supports not only PCI / Cardbus but also USB
50 and SPI. Since p54pci supports all devices prism54 supports
51 you will have a conflict. I'm not quite sure how distributions are
52 handling this conflict right now. prism54 was kept around due to
53 claims users may experience issues when using the SoftMAC driver.
54 Time has passed users have not reported issues. If you use prism54
55 and for whatever reason you cannot use p54pci please let us know!
56 E-mail us at: linux-wireless@vger.kernel.org
58 For more information see the p54 wiki page:
60 http://wireless.kernel.org/en/users/Drivers/p54
62 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
64 ---------------------------
66 What: IRQF_SAMPLE_RANDOM
67 Check: IRQF_SAMPLE_RANDOM
68 When: July 2009
70 Why: Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy
71 sources in the kernel's current entropy model. To resolve this, every
72 input point to the kernel's entropy pool needs to better document the
73 type of entropy source it actually is. This will be replaced with
74 additional add_*_randomness functions in drivers/char/random.c
76 Who: Robin Getz <rgetz@blackfin.uclinux.org> & Matt Mackall <mpm@selenic.com>
78 ---------------------------
80 What: The ieee80211_regdom module parameter
81 When: March 2010 / desktop catchup
83 Why: This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code,
84 and currently serves as an option for users to define an
85 ISO / IEC 3166 alpha2 code for the country they are currently
86 present in. Although there are userspace API replacements for this
87 through nl80211 distributions haven't yet caught up with implementing
88 decent alternatives through standard GUIs. Although available as an
89 option through iw or wpa_supplicant its just a matter of time before
90 distributions pick up good GUI options for this. The ideal solution
91 would actually consist of intelligent designs which would do this for
92 the user automatically even when travelling through different countries.
93 Until then we leave this module parameter as a compromise.
95 When userspace improves with reasonable widely-available alternatives for
96 this we will no longer need this module parameter. This entry hopes that
97 by the super-futuristically looking date of "March 2010" we will have
98 such replacements widely available.
100 Who: Luis R. Rodriguez <lrodriguez@atheros.com>
102 ---------------------------
104 What: dev->power.power_state
105 When: July 2007
106 Why: Broken design for runtime control over driver power states, confusing
107 driver-internal runtime power management with: mechanisms to support
108 system-wide sleep state transitions; event codes that distinguish
109 different phases of swsusp "sleep" transitions; and userspace policy
110 inputs. This framework was never widely used, and most attempts to
111 use it were broken. Drivers should instead be exposing domain-specific
112 interfaces either to kernel or to userspace.
113 Who: Pavel Machek <pavel@ucw.cz>
115 ---------------------------
117 What: /proc/<pid>/oom_adj
118 When: August 2012
119 Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
120 badness heuristic used to determine which task to kill when the kernel
121 is out of memory.
123 The badness heuristic has since been rewritten since the introduction of
124 this tunable such that its meaning is deprecated. The value was
125 implemented as a bitshift on a score generated by the badness()
126 function that did not have any precise units of measure. With the
127 rewrite, the score is given as a proportion of available memory to the
128 task allocating pages, so using a bitshift which grows the score
129 exponentially is, thus, impossible to tune with fine granularity.
131 A much more powerful interface, /proc/<pid>/oom_score_adj, was
132 introduced with the oom killer rewrite that allows users to increase or
133 decrease the badness score linearly. This interface will replace
134 /proc/<pid>/oom_adj.
136 A warning will be emitted to the kernel log if an application uses this
137 deprecated interface. After it is printed once, future warnings will be
138 suppressed until the kernel is rebooted.
140 ---------------------------
142 What: remove EXPORT_SYMBOL(kernel_thread)
143 When: August 2006
144 Files: arch/*/kernel/*_ksyms.c
145 Check: kernel_thread
146 Why: kernel_thread is a low-level implementation detail. Drivers should
147 use the <linux/kthread.h> API instead which shields them from
148 implementation details and provides a higherlevel interface that
149 prevents bugs and code duplication
150 Who: Christoph Hellwig <hch@lst.de>
152 ---------------------------
154 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
155 (temporary transition config option provided until then)
156 The transition config option will also be removed at the same time.
157 When: before 2.6.19
158 Why: Unused symbols are both increasing the size of the kernel binary
159 and are often a sign of "wrong API"
160 Who: Arjan van de Ven <arjan@linux.intel.com>
162 ---------------------------
164 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
165 When: October 2008
166 Why: The stacking of class devices makes these values misleading and
167 inconsistent.
168 Class devices should not carry any of these properties, and bus
169 devices have SUBSYTEM and DRIVER as a replacement.
170 Who: Kay Sievers <kay.sievers@suse.de>
172 ---------------------------
174 What: ACPI procfs interface
175 When: July 2008
176 Why: ACPI sysfs conversion should be finished by January 2008.
177 ACPI procfs interface will be removed in July 2008 so that
178 there is enough time for the user space to catch up.
179 Who: Zhang Rui <rui.zhang@intel.com>
181 ---------------------------
183 What: CONFIG_ACPI_PROCFS_POWER
184 When: 2.6.39
185 Why: sysfs I/F for ACPI power devices, including AC and Battery,
186 has been working in upstream kernel since 2.6.24, Sep 2007.
187 In 2.6.37, we make the sysfs I/F always built in and this option
188 disabled by default.
189 Remove this option and the ACPI power procfs interface in 2.6.39.
190 Who: Zhang Rui <rui.zhang@intel.com>
192 ---------------------------
194 What: /proc/acpi/event
195 When: February 2008
196 Why: /proc/acpi/event has been replaced by events via the input layer
197 and netlink since 2.6.23.
198 Who: Len Brown <len.brown@intel.com>
200 ---------------------------
202 What: i386/x86_64 bzImage symlinks
203 When: April 2010
205 Why: The i386/x86_64 merge provides a symlink to the old bzImage
206 location so not yet updated user space tools, e.g. package
207 scripts, do not break.
208 Who: Thomas Gleixner <tglx@linutronix.de>
210 ---------------------------
212 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
213 When: February 2010
214 Why: All callers should use explicit gpio_request()/gpio_free().
215 The autorequest mechanism in gpiolib was provided mostly as a
216 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
217 Those users have now largely migrated. Platforms implementing
218 the GPIO interfaces without using gpiolib will see no changes.
219 Who: David Brownell <dbrownell@users.sourceforge.net>
220 ---------------------------
222 What: b43 support for firmware revision < 410
223 When: The schedule was July 2008, but it was decided that we are going to keep the
224 code as long as there are no major maintanance headaches.
225 So it _could_ be removed _any_ time now, if it conflicts with something new.
226 Why: The support code for the old firmware hurts code readability/maintainability
227 and slightly hurts runtime performance. Bugfixes for the old firmware
228 are not provided by Broadcom anymore.
229 Who: Michael Buesch <m@bues.ch>
231 ---------------------------
233 What: Ability for non root users to shm_get hugetlb pages based on mlock
234 resource limits
235 When: 2.6.31
236 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
237 have CAP_IPC_LOCK to be able to allocate shm segments backed by
238 huge pages. The mlock based rlimit check to allow shm hugetlb is
239 inconsistent with mmap based allocations. Hence it is being
240 deprecated.
241 Who: Ravikiran Thirumalai <kiran@scalex86.org>
243 ---------------------------
245 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
246 (in net/core/net-sysfs.c)
247 When: 3.5
248 Why: Over 1K .text/.data size reduction, data is available in other
249 ways (ioctls)
250 Who: Johannes Berg <johannes@sipsolutions.net>
252 ---------------------------
254 What: sysfs ui for changing p4-clockmod parameters
255 When: September 2009
256 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
257 e088e4c9cdb618675874becb91b2fd581ee707e6.
258 Removal is subject to fixing any remaining bugs in ACPI which may
259 cause the thermal throttling not to happen at the right time.
260 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
262 -----------------------------
264 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
265 When: 2011
266 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
267 represent a machine's physical PCI slots. The change in semantics
268 had userspace implications, as the hotplug core no longer allowed
269 drivers to create multiple sysfs files per physical slot (required
270 for multi-function devices, e.g.). fakephp was seen as a developer's
271 tool only, and its interface changed. Too late, we learned that
272 there were some users of the fakephp interface.
274 In 2.6.30, the original fakephp interface was restored. At the same
275 time, the PCI core gained the ability that fakephp provided, namely
276 function-level hot-remove and hot-add.
278 Since the PCI core now provides the same functionality, exposed in:
280 /sys/bus/pci/rescan
281 /sys/bus/pci/devices/.../remove
282 /sys/bus/pci/devices/.../rescan
284 there is no functional reason to maintain fakephp as well.
286 We will keep the existing module so that 'modprobe fakephp' will
287 present the old /sys/bus/pci/slots/... interface for compatibility,
288 but users are urged to migrate their applications to the API above.
290 After a reasonable transition period, we will remove the legacy
291 fakephp interface.
292 Who: Alex Chiang <achiang@hp.com>
294 ---------------------------
296 What: CONFIG_RFKILL_INPUT
297 When: 2.6.33
298 Why: Should be implemented in userspace, policy daemon.
299 Who: Johannes Berg <johannes@sipsolutions.net>
301 ----------------------------
303 What: sound-slot/service-* module aliases and related clutters in
304 sound/sound_core.c
305 When: August 2010
306 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
307 (14) and requests modules using custom sound-slot/service-*
308 module aliases. The only benefit of doing this is allowing
309 use of custom module aliases which might as well be considered
310 a bug at this point. This preemptive claiming prevents
311 alternative OSS implementations.
313 Till the feature is removed, the kernel will be requesting
314 both sound-slot/service-* and the standard char-major-* module
315 aliases and allow turning off the pre-claiming selectively via
316 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
317 kernel parameter.
319 After the transition phase is complete, both the custom module
320 aliases and switches to disable it will go away. This removal
321 will also allow making ALSA OSS emulation independent of
322 sound_core. The dependency will be broken then too.
323 Who: Tejun Heo <tj@kernel.org>
325 ----------------------------
327 What: sysfs-class-rfkill state file
328 When: Feb 2014
329 Files: net/rfkill/core.c
330 Why: Documented as obsolete since Feb 2010. This file is limited to 3
331 states while the rfkill drivers can have 4 states.
332 Who: anybody or Florian Mickler <florian@mickler.org>
334 ----------------------------
336 What: sysfs-class-rfkill claim file
337 When: Feb 2012
338 Files: net/rfkill/core.c
339 Why: It is not possible to claim an rfkill driver since 2007. This is
340 Documented as obsolete since Feb 2010.
341 Who: anybody or Florian Mickler <florian@mickler.org>
343 ----------------------------
345 What: iwlwifi 50XX module parameters
346 When: 3.0
347 Why: The "..50" modules parameters were used to configure 5000 series and
348 up devices; different set of module parameters also available for 4965
349 with same functionalities. Consolidate both set into single place
350 in drivers/net/wireless/iwlwifi/iwl-agn.c
352 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
354 ----------------------------
356 What: iwl4965 alias support
357 When: 3.0
358 Why: Internal alias support has been present in module-init-tools for some
359 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
360 with no impact.
362 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
364 ---------------------------
366 What: xt_NOTRACK
367 Files: net/netfilter/xt_NOTRACK.c
368 When: April 2011
369 Why: Superseded by xt_CT
370 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
372 ----------------------------
374 What: IRQF_DISABLED
375 When: 2.6.36
376 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
377 Who: Thomas Gleixner <tglx@linutronix.de>
379 ----------------------------
381 What: PCI DMA unmap state API
382 When: August 2012
383 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
384 with DMA unmap state API (DMA unmap state API can be used for
385 any bus).
386 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
388 ----------------------------
390 What: iwlwifi disable_hw_scan module parameters
391 When: 3.0
392 Why: Hareware scan is the prefer method for iwlwifi devices for
393 scanning operation. Remove software scan support for all the
394 iwlwifi devices.
396 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
398 ----------------------------
400 What: Legacy, non-standard chassis intrusion detection interface.
401 When: June 2011
402 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
403 legacy interfaces for chassis intrusion detection. A standard
404 interface has been added to each driver, so the legacy interface
405 can be removed.
406 Who: Jean Delvare <khali@linux-fr.org>
408 ----------------------------
410 What: xt_connlimit rev 0
411 When: 2012
412 Who: Jan Engelhardt <jengelh@medozas.de>
413 Files: net/netfilter/xt_connlimit.c
415 ----------------------------
417 What: ipt_addrtype match include file
418 When: 2012
419 Why: superseded by xt_addrtype
420 Who: Florian Westphal <fw@strlen.de>
421 Files: include/linux/netfilter_ipv4/ipt_addrtype.h
423 ----------------------------
425 What: i2c_driver.attach_adapter
426 i2c_driver.detach_adapter
427 When: September 2011
428 Why: These legacy callbacks should no longer be used as i2c-core offers
429 a variety of preferable alternative ways to instantiate I2C devices.
430 Who: Jean Delvare <khali@linux-fr.org>
432 ----------------------------
434 What: Opening a radio device node will no longer automatically switch the
435 tuner mode from tv to radio.
436 When: 3.3
437 Why: Just opening a V4L device should not change the state of the hardware
438 like that. It's very unexpected and against the V4L spec. Instead, you
439 switch to radio mode by calling VIDIOC_S_FREQUENCY. This is the second
440 and last step of the move to consistent handling of tv and radio tuners.
441 Who: Hans Verkuil <hans.verkuil@cisco.com>
443 ----------------------------
445 What: g_file_storage driver
446 When: 3.8
447 Why: This driver has been superseded by g_mass_storage.
448 Who: Alan Stern <stern@rowland.harvard.edu>
450 ----------------------------
452 What: threeg and interface sysfs files in /sys/devices/platform/acer-wmi
453 When: 2012
454 Why: In 3.0, we can now autodetect internal 3G device and already have
455 the threeg rfkill device. So, we plan to remove threeg sysfs support
456 for it's no longer necessary.
458 We also plan to remove interface sysfs file that exposed which ACPI-WMI
459 interface that was used by acer-wmi driver. It will replaced by
460 information log when acer-wmi initial.
461 Who: Lee, Chun-Yi <jlee@novell.com>
463 ---------------------------
465 What: /sys/devices/platform/_UDC_/udc/_UDC_/is_dualspeed file and
466 is_dualspeed line in /sys/devices/platform/ci13xxx_*/udc/device file.
467 When: 3.8
468 Why: The is_dualspeed file is superseded by maximum_speed in the same
469 directory and is_dualspeed line in device file is superseded by
470 max_speed line in the same file.
472 The maximum_speed/max_speed specifies maximum speed supported by UDC.
473 To check if dualspeeed is supported, check if the value is >= 3.
474 Various possible speeds are defined in <linux/usb/ch9.h>.
475 Who: Michal Nazarewicz <mina86@mina86.com>
477 ----------------------------
479 What: The XFS nodelaylog mount option
480 When: 3.3
481 Why: The delaylog mode that has been the default since 2.6.39 has proven
482 stable, and the old code is in the way of additional improvements in
483 the log code.
484 Who: Christoph Hellwig <hch@lst.de>
486 ----------------------------
488 What: iwlagn alias support
489 When: 3.5
490 Why: The iwlagn module has been renamed iwlwifi. The alias will be around
491 for backward compatibility for several cycles and then dropped.
492 Who: Don Fry <donald.h.fry@intel.com>
494 ----------------------------
496 What: pci_scan_bus_parented()
497 When: 3.5
498 Why: The pci_scan_bus_parented() interface creates a new root bus. The
499 bus is created with default resources (ioport_resource and
500 iomem_resource) that are always wrong, so we rely on arch code to
501 correct them later. Callers of pci_scan_bus_parented() should
502 convert to using pci_scan_root_bus() so they can supply a list of
503 bus resources when the bus is created.
504 Who: Bjorn Helgaas <bhelgaas@google.com>
506 ----------------------------
508 What: Low Performance USB Block driver ("CONFIG_BLK_DEV_UB")
509 When: 3.6
510 Why: This driver provides support for USB storage devices like "USB
511 sticks". As of now, it is deactivated in Debian, Fedora and
512 Ubuntu. All current users can switch over to usb-storage
513 (CONFIG_USB_STORAGE) which only drawback is the additional SCSI
514 stack.
515 Who: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
517 ----------------------------
519 What: kmap_atomic(page, km_type)
520 When: 3.5
521 Why: The old kmap_atomic() with two arguments is deprecated, we only
522 keep it for backward compatibility for few cycles and then drop it.
523 Who: Cong Wang <amwang@redhat.com>
525 ----------------------------
527 What: get_robust_list syscall
528 When: 2013
529 Why: There appear to be no production users of the get_robust_list syscall,
530 and it runs the risk of leaking address locations, allowing the bypass
531 of ASLR. It was only ever intended for debugging, so it should be
532 removed.
533 Who: Kees Cook <keescook@chromium.org>