| blob | c4a6e148732ae549be7e25b8863912a2f924d254 |
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: remove EXPORT_SYMBOL(kernel_thread)
197 When: August 2006
198 Files: arch/*/kernel/*_ksyms.c
199 Check: kernel_thread
200 Why: kernel_thread is a low-level implementation detail. Drivers should
201 use the <linux/kthread.h> API instead which shields them from
202 implementation details and provides a higherlevel interface that
203 prevents bugs and code duplication
204 Who: Christoph Hellwig <hch@lst.de>
206 ---------------------------
208 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
209 (temporary transition config option provided until then)
210 The transition config option will also be removed at the same time.
211 When: before 2.6.19
212 Why: Unused symbols are both increasing the size of the kernel binary
213 and are often a sign of "wrong API"
214 Who: Arjan van de Ven <arjan@linux.intel.com>
216 ---------------------------
218 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
219 When: October 2008
220 Why: The stacking of class devices makes these values misleading and
221 inconsistent.
222 Class devices should not carry any of these properties, and bus
223 devices have SUBSYTEM and DRIVER as a replacement.
224 Who: Kay Sievers <kay.sievers@suse.de>
226 ---------------------------
228 What: ACPI procfs interface
229 When: July 2008
230 Why: ACPI sysfs conversion should be finished by January 2008.
231 ACPI procfs interface will be removed in July 2008 so that
232 there is enough time for the user space to catch up.
233 Who: Zhang Rui <rui.zhang@intel.com>
235 ---------------------------
237 What: CONFIG_ACPI_PROCFS_POWER
238 When: 2.6.39
239 Why: sysfs I/F for ACPI power devices, including AC and Battery,
240 has been working in upstream kernel since 2.6.24, Sep 2007.
241 In 2.6.37, we make the sysfs I/F always built in and this option
242 disabled by default.
243 Remove this option and the ACPI power procfs interface in 2.6.39.
244 Who: Zhang Rui <rui.zhang@intel.com>
246 ---------------------------
248 What: /proc/acpi/event
249 When: February 2008
250 Why: /proc/acpi/event has been replaced by events via the input layer
251 and netlink since 2.6.23.
252 Who: Len Brown <len.brown@intel.com>
254 ---------------------------
256 What: i386/x86_64 bzImage symlinks
257 When: April 2010
259 Why: The i386/x86_64 merge provides a symlink to the old bzImage
260 location so not yet updated user space tools, e.g. package
261 scripts, do not break.
262 Who: Thomas Gleixner <tglx@linutronix.de>
264 ---------------------------
266 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
267 When: February 2010
268 Why: All callers should use explicit gpio_request()/gpio_free().
269 The autorequest mechanism in gpiolib was provided mostly as a
270 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
271 Those users have now largely migrated. Platforms implementing
272 the GPIO interfaces without using gpiolib will see no changes.
273 Who: David Brownell <dbrownell@users.sourceforge.net>
274 ---------------------------
276 What: b43 support for firmware revision < 410
277 When: The schedule was July 2008, but it was decided that we are going to keep the
278 code as long as there are no major maintanance headaches.
279 So it _could_ be removed _any_ time now, if it conflicts with something new.
280 Why: The support code for the old firmware hurts code readability/maintainability
281 and slightly hurts runtime performance. Bugfixes for the old firmware
282 are not provided by Broadcom anymore.
283 Who: Michael Buesch <m@bues.ch>
285 ---------------------------
287 What: Ability for non root users to shm_get hugetlb pages based on mlock
288 resource limits
289 When: 2.6.31
290 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
291 have CAP_IPC_LOCK to be able to allocate shm segments backed by
292 huge pages. The mlock based rlimit check to allow shm hugetlb is
293 inconsistent with mmap based allocations. Hence it is being
294 deprecated.
295 Who: Ravikiran Thirumalai <kiran@scalex86.org>
297 ---------------------------
299 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
300 (in net/core/net-sysfs.c)
301 When: After the only user (hal) has seen a release with the patches
302 for enough time, probably some time in 2010.
303 Why: Over 1K .text/.data size reduction, data is available in other
304 ways (ioctls)
305 Who: Johannes Berg <johannes@sipsolutions.net>
307 ---------------------------
309 What: sysfs ui for changing p4-clockmod parameters
310 When: September 2009
311 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
312 e088e4c9cdb618675874becb91b2fd581ee707e6.
313 Removal is subject to fixing any remaining bugs in ACPI which may
314 cause the thermal throttling not to happen at the right time.
315 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
317 -----------------------------
319 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
320 When: 2011
321 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
322 represent a machine's physical PCI slots. The change in semantics
323 had userspace implications, as the hotplug core no longer allowed
324 drivers to create multiple sysfs files per physical slot (required
325 for multi-function devices, e.g.). fakephp was seen as a developer's
326 tool only, and its interface changed. Too late, we learned that
327 there were some users of the fakephp interface.
329 In 2.6.30, the original fakephp interface was restored. At the same
330 time, the PCI core gained the ability that fakephp provided, namely
331 function-level hot-remove and hot-add.
333 Since the PCI core now provides the same functionality, exposed in:
335 /sys/bus/pci/rescan
336 /sys/bus/pci/devices/.../remove
337 /sys/bus/pci/devices/.../rescan
339 there is no functional reason to maintain fakephp as well.
341 We will keep the existing module so that 'modprobe fakephp' will
342 present the old /sys/bus/pci/slots/... interface for compatibility,
343 but users are urged to migrate their applications to the API above.
345 After a reasonable transition period, we will remove the legacy
346 fakephp interface.
347 Who: Alex Chiang <achiang@hp.com>
349 ---------------------------
351 What: CONFIG_RFKILL_INPUT
352 When: 2.6.33
353 Why: Should be implemented in userspace, policy daemon.
354 Who: Johannes Berg <johannes@sipsolutions.net>
356 ----------------------------
358 What: sound-slot/service-* module aliases and related clutters in
359 sound/sound_core.c
360 When: August 2010
361 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
362 (14) and requests modules using custom sound-slot/service-*
363 module aliases. The only benefit of doing this is allowing
364 use of custom module aliases which might as well be considered
365 a bug at this point. This preemptive claiming prevents
366 alternative OSS implementations.
368 Till the feature is removed, the kernel will be requesting
369 both sound-slot/service-* and the standard char-major-* module
370 aliases and allow turning off the pre-claiming selectively via
371 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
372 kernel parameter.
374 After the transition phase is complete, both the custom module
375 aliases and switches to disable it will go away. This removal
376 will also allow making ALSA OSS emulation independent of
377 sound_core. The dependency will be broken then too.
378 Who: Tejun Heo <tj@kernel.org>
380 ----------------------------
382 What: sysfs-class-rfkill state file
383 When: Feb 2014
384 Files: net/rfkill/core.c
385 Why: Documented as obsolete since Feb 2010. This file is limited to 3
386 states while the rfkill drivers can have 4 states.
387 Who: anybody or Florian Mickler <florian@mickler.org>
389 ----------------------------
391 What: sysfs-class-rfkill claim file
392 When: Feb 2012
393 Files: net/rfkill/core.c
394 Why: It is not possible to claim an rfkill driver since 2007. This is
395 Documented as obsolete since Feb 2010.
396 Who: anybody or Florian Mickler <florian@mickler.org>
398 ----------------------------
400 What: KVM paravirt mmu host support
401 When: January 2011
402 Why: The paravirt mmu host support is slower than non-paravirt mmu, both
403 on newer and older hardware. It is already not exposed to the guest,
404 and kept only for live migration purposes.
405 Who: Avi Kivity <avi@redhat.com>
407 ----------------------------
409 What: iwlwifi 50XX module parameters
410 When: 3.0
411 Why: The "..50" modules parameters were used to configure 5000 series and
412 up devices; different set of module parameters also available for 4965
413 with same functionalities. Consolidate both set into single place
414 in drivers/net/wireless/iwlwifi/iwl-agn.c
416 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
418 ----------------------------
420 What: iwl4965 alias support
421 When: 3.0
422 Why: Internal alias support has been present in module-init-tools for some
423 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
424 with no impact.
426 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
428 ---------------------------
430 What: xt_NOTRACK
431 Files: net/netfilter/xt_NOTRACK.c
432 When: April 2011
433 Why: Superseded by xt_CT
434 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
436 ----------------------------
438 What: IRQF_DISABLED
439 When: 2.6.36
440 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
441 Who: Thomas Gleixner <tglx@linutronix.de>
443 ----------------------------
445 What: PCI DMA unmap state API
446 When: August 2012
447 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
448 with DMA unmap state API (DMA unmap state API can be used for
449 any bus).
450 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
452 ----------------------------
454 What: iwlwifi disable_hw_scan module parameters
455 When: 3.0
456 Why: Hareware scan is the prefer method for iwlwifi devices for
457 scanning operation. Remove software scan support for all the
458 iwlwifi devices.
460 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
462 ----------------------------
464 What: Legacy, non-standard chassis intrusion detection interface.
465 When: June 2011
466 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
467 legacy interfaces for chassis intrusion detection. A standard
468 interface has been added to each driver, so the legacy interface
469 can be removed.
470 Who: Jean Delvare <khali@linux-fr.org>
472 ----------------------------
474 What: xt_connlimit rev 0
475 When: 2012
476 Who: Jan Engelhardt <jengelh@medozas.de>
477 Files: net/netfilter/xt_connlimit.c
479 ----------------------------
481 What: ipt_addrtype match include file
482 When: 2012
483 Why: superseded by xt_addrtype
484 Who: Florian Westphal <fw@strlen.de>
485 Files: include/linux/netfilter_ipv4/ipt_addrtype.h
487 ----------------------------
489 What: i2c_driver.attach_adapter
490 i2c_driver.detach_adapter
491 When: September 2011
492 Why: These legacy callbacks should no longer be used as i2c-core offers
493 a variety of preferable alternative ways to instantiate I2C devices.
494 Who: Jean Delvare <khali@linux-fr.org>
496 ----------------------------
498 What: Support for UVCIOC_CTRL_ADD in the uvcvideo driver
499 When: 3.2
500 Why: The information passed to the driver by this ioctl is now queried
501 dynamically from the device.
502 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
504 ----------------------------
506 What: Support for UVCIOC_CTRL_MAP_OLD in the uvcvideo driver
507 When: 3.2
508 Why: Used only by applications compiled against older driver versions.
509 Superseded by UVCIOC_CTRL_MAP which supports V4L2 menu controls.
510 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
512 ----------------------------
514 What: Support for UVCIOC_CTRL_GET and UVCIOC_CTRL_SET in the uvcvideo driver
515 When: 3.2
516 Why: Superseded by the UVCIOC_CTRL_QUERY ioctl.
517 Who: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
519 ----------------------------
521 What: Support for driver specific ioctls in the pwc driver (everything
522 defined in media/pwc-ioctl.h)
523 When: 3.3
524 Why: This stems from the v4l1 era, with v4l2 everything can be done with
525 standardized v4l2 API calls
526 Who: Hans de Goede <hdegoede@redhat.com>
528 ----------------------------
530 What: Driver specific sysfs API in the pwc driver
531 When: 3.3
532 Why: Setting pan/tilt should be done with v4l2 controls, like with other
533 cams. The button is available as a standard input device
534 Who: Hans de Goede <hdegoede@redhat.com>
536 ----------------------------
538 What: Driver specific use of pixfmt.priv in the pwc driver
539 When: 3.3
540 Why: The .priv field never was intended for this, setting a framerate is
541 support using the standardized S_PARM ioctl
542 Who: Hans de Goede <hdegoede@redhat.com>
544 ----------------------------
546 What: Software emulation of arbritary resolutions in the pwc driver
547 When: 3.3
548 Why: The pwc driver claims to support any resolution between 160x120
549 and 640x480, but emulates this by simply drawing a black border
550 around the image. Userspace can draw its own black border if it
551 really wants one.
552 Who: Hans de Goede <hdegoede@redhat.com>
554 ----------------------------
556 What: For VIDIOC_S_FREQUENCY the type field must match the device node's type.
557 If not, return -EINVAL.
558 When: 3.2
559 Why: It makes no sense to switch the tuner to radio mode by calling
560 VIDIOC_S_FREQUENCY on a video node, or to switch the tuner to tv mode by
561 calling VIDIOC_S_FREQUENCY on a radio node. This is the first step of a
562 move to more consistent handling of tv and radio tuners.
563 Who: Hans Verkuil <hans.verkuil@cisco.com>
565 ----------------------------
567 What: Opening a radio device node will no longer automatically switch the
568 tuner mode from tv to radio.
569 When: 3.3
570 Why: Just opening a V4L device should not change the state of the hardware
571 like that. It's very unexpected and against the V4L spec. Instead, you
572 switch to radio mode by calling VIDIOC_S_FREQUENCY. This is the second
573 and last step of the move to consistent handling of tv and radio tuners.
574 Who: Hans Verkuil <hans.verkuil@cisco.com>
576 ----------------------------
578 What: g_file_storage driver
579 When: 3.8
580 Why: This driver has been superseded by g_mass_storage.
581 Who: Alan Stern <stern@rowland.harvard.edu>
583 ----------------------------
585 What: threeg and interface sysfs files in /sys/devices/platform/acer-wmi
586 When: 2012
587 Why: In 3.0, we can now autodetect internal 3G device and already have
588 the threeg rfkill device. So, we plan to remove threeg sysfs support
589 for it's no longer necessary.
591 We also plan to remove interface sysfs file that exposed which ACPI-WMI
592 interface that was used by acer-wmi driver. It will replaced by
593 information log when acer-wmi initial.
594 Who: Lee, Chun-Yi <jlee@novell.com>