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
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
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
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
40 Why: simplify x86 idle code
41 Who: Len Brown <len.brown@intel.com>
43 ----------------------------
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
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
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
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: Video4Linux obsolete drivers using V4L1 API
138 Files: drivers/staging/se401/* drivers/staging/usbvideo/*
139 Check: drivers/staging/se401/se401.c drivers/staging/usbvideo/usbvideo.c
140 Why: There are some drivers still using V4L1 API, despite all efforts we've done
141 to migrate. Those drivers are for obsolete hardware that the old maintainer
142 didn't care (or not have the hardware anymore), and that no other developer
143 could find any hardware to buy. They probably have no practical usage today,
144 and people with such old hardware could probably keep using an older version
145 of the kernel. Those drivers will be moved to staging on 2.6.38 and, if nobody
146 cares enough to port and test them with V4L2 API, they'll be removed on 2.6.39.
147 Who: Mauro Carvalho Chehab <mchehab@infradead.org>
149 ---------------------------
151 What: Video4Linux: Remove obsolete ioctl's
153 Files: include/media/videodev2.h
154 Why: Some ioctl's were defined wrong on 2.6.2 and 2.6.6, using the wrong
155 type of R/W arguments. They were fixed, but the old ioctl names are
156 still there, maintained to avoid breaking binary compatibility:
157 #define VIDIOC_OVERLAY_OLD _IOWR('V', 14, int)
158 #define VIDIOC_S_PARM_OLD _IOW('V', 22, struct v4l2_streamparm)
159 #define VIDIOC_S_CTRL_OLD _IOW('V', 28, struct v4l2_control)
160 #define VIDIOC_G_AUDIO_OLD _IOWR('V', 33, struct v4l2_audio)
161 #define VIDIOC_G_AUDOUT_OLD _IOWR('V', 49, struct v4l2_audioout)
162 #define VIDIOC_CROPCAP_OLD _IOR('V', 58, struct v4l2_cropcap)
163 There's no sense on preserving those forever, as it is very doubtful
164 that someone would try to use a such old binary with a modern kernel.
165 Removing them will allow us to remove some magic done at the V4L ioctl
168 Who: Mauro Carvalho Chehab <mchehab@infradead.org>
170 ---------------------------
174 Option: CONFIG_SYSCTL_SYSCALL
175 Why: The same information is available in a more convenient from
176 /proc/sys, and none of the sysctl variables appear to be
177 important performance wise.
179 Binary sysctls are a long standing source of subtle kernel
180 bugs and security issues.
182 When I looked several months ago all I could find after
183 searching several distributions were 5 user space programs and
184 glibc (which falls back to /proc/sys) using this syscall.
186 The man page for sysctl(2) documents it as unusable for user
189 sysctl(2) is not generally ABI compatible to a 32bit user
190 space application on a 64bit and a 32bit kernel.
192 For the last several months the policy has been no new binary
193 sysctls and no one has put forward an argument to use them.
195 Binary sysctls issues seem to keep happening appearing so
196 properly deprecating them (with a warning to user space) and a
197 2 year grace warning period will mean eventually we can kill
198 them and end the pain.
200 In the mean time individual binary sysctls can be dealt with
201 in a piecewise fashion.
203 Who: Eric Biederman <ebiederm@xmission.com>
205 ---------------------------
207 What: /proc/<pid>/oom_adj
209 Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
210 badness heuristic used to determine which task to kill when the kernel
213 The badness heuristic has since been rewritten since the introduction of
214 this tunable such that its meaning is deprecated. The value was
215 implemented as a bitshift on a score generated by the badness()
216 function that did not have any precise units of measure. With the
217 rewrite, the score is given as a proportion of available memory to the
218 task allocating pages, so using a bitshift which grows the score
219 exponentially is, thus, impossible to tune with fine granularity.
221 A much more powerful interface, /proc/<pid>/oom_score_adj, was
222 introduced with the oom killer rewrite that allows users to increase or
223 decrease the badness() score linearly. This interface will replace
226 A warning will be emitted to the kernel log if an application uses this
227 deprecated interface. After it is printed once, future warnings will be
228 suppressed until the kernel is rebooted.
230 ---------------------------
232 What: CS5535/CS5536 obsolete GPIO driver
234 Files: drivers/staging/cs5535_gpio/*
235 Check: drivers/staging/cs5535_gpio/cs5535_gpio.c
236 Why: A newer driver replaces this; it is drivers/gpio/cs5535-gpio.c, and
237 integrates with the Linux GPIO subsystem. The old driver has been
238 moved to staging, and will be removed altogether around 2.6.40.
239 Please test the new driver, and ensure that the functionality you
240 need and any bugfixes from the old driver are available in the new
242 Who: Andres Salomon <dilinger@queued.net>
244 --------------------------
246 What: remove EXPORT_SYMBOL(kernel_thread)
248 Files: arch/*/kernel/*_ksyms.c
250 Why: kernel_thread is a low-level implementation detail. Drivers should
251 use the <linux/kthread.h> API instead which shields them from
252 implementation details and provides a higherlevel interface that
253 prevents bugs and code duplication
254 Who: Christoph Hellwig <hch@lst.de>
256 ---------------------------
258 What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
259 (temporary transition config option provided until then)
260 The transition config option will also be removed at the same time.
262 Why: Unused symbols are both increasing the size of the kernel binary
263 and are often a sign of "wrong API"
264 Who: Arjan van de Ven <arjan@linux.intel.com>
266 ---------------------------
268 What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
270 Why: The stacking of class devices makes these values misleading and
272 Class devices should not carry any of these properties, and bus
273 devices have SUBSYTEM and DRIVER as a replacement.
274 Who: Kay Sievers <kay.sievers@suse.de>
276 ---------------------------
278 What: ACPI procfs interface
280 Why: ACPI sysfs conversion should be finished by January 2008.
281 ACPI procfs interface will be removed in July 2008 so that
282 there is enough time for the user space to catch up.
283 Who: Zhang Rui <rui.zhang@intel.com>
285 ---------------------------
287 What: CONFIG_ACPI_PROCFS_POWER
289 Why: sysfs I/F for ACPI power devices, including AC and Battery,
290 has been working in upstream kenrel since 2.6.24, Sep 2007.
291 In 2.6.37, we make the sysfs I/F always built in and this option
293 Remove this option and the ACPI power procfs interface in 2.6.39.
294 Who: Zhang Rui <rui.zhang@intel.com>
296 ---------------------------
298 What: /proc/acpi/button
300 Why: /proc/acpi/button has been replaced by events to the input layer
302 Who: Len Brown <len.brown@intel.com>
304 ---------------------------
306 What: /proc/acpi/event
308 Why: /proc/acpi/event has been replaced by events via the input layer
309 and netlink since 2.6.23.
310 Who: Len Brown <len.brown@intel.com>
312 ---------------------------
314 What: i386/x86_64 bzImage symlinks
317 Why: The i386/x86_64 merge provides a symlink to the old bzImage
318 location so not yet updated user space tools, e.g. package
319 scripts, do not break.
320 Who: Thomas Gleixner <tglx@linutronix.de>
322 ---------------------------
324 What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
326 Why: All callers should use explicit gpio_request()/gpio_free().
327 The autorequest mechanism in gpiolib was provided mostly as a
328 migration aid for legacy GPIO interfaces (for SOC based GPIOs).
329 Those users have now largely migrated. Platforms implementing
330 the GPIO interfaces without using gpiolib will see no changes.
331 Who: David Brownell <dbrownell@users.sourceforge.net>
332 ---------------------------
334 What: b43 support for firmware revision < 410
335 When: The schedule was July 2008, but it was decided that we are going to keep the
336 code as long as there are no major maintanance headaches.
337 So it _could_ be removed _any_ time now, if it conflicts with something new.
338 Why: The support code for the old firmware hurts code readability/maintainability
339 and slightly hurts runtime performance. Bugfixes for the old firmware
340 are not provided by Broadcom anymore.
341 Who: Michael Buesch <mb@bu3sch.de>
343 ---------------------------
345 What: /sys/o2cb symlink
347 Why: /sys/fs/o2cb is the proper location for this information - /sys/o2cb
348 exists as a symlink for backwards compatibility for old versions of
349 ocfs2-tools. 2 years should be sufficient time to phase in new versions
350 which know to look in /sys/fs/o2cb.
351 Who: ocfs2-devel@oss.oracle.com
353 ---------------------------
355 What: Ability for non root users to shm_get hugetlb pages based on mlock
358 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
359 have CAP_IPC_LOCK to be able to allocate shm segments backed by
360 huge pages. The mlock based rlimit check to allow shm hugetlb is
361 inconsistent with mmap based allocations. Hence it is being
363 Who: Ravikiran Thirumalai <kiran@scalex86.org>
365 ---------------------------
367 What: CONFIG_THERMAL_HWMON
369 Why: This option was introduced just to allow older lm-sensors userspace
370 to keep working over the upgrade to 2.6.26. At the scheduled time of
371 removal fixed lm-sensors (2.x or 3.x) should be readily available.
372 Who: Rene Herman <rene.herman@gmail.com>
374 ---------------------------
376 What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS
377 (in net/core/net-sysfs.c)
378 When: After the only user (hal) has seen a release with the patches
379 for enough time, probably some time in 2010.
380 Why: Over 1K .text/.data size reduction, data is available in other
382 Who: Johannes Berg <johannes@sipsolutions.net>
384 ---------------------------
386 What: sysfs ui for changing p4-clockmod parameters
388 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and
389 e088e4c9cdb618675874becb91b2fd581ee707e6.
390 Removal is subject to fixing any remaining bugs in ACPI which may
391 cause the thermal throttling not to happen at the right time.
392 Who: Dave Jones <davej@redhat.com>, Matthew Garrett <mjg@redhat.com>
394 -----------------------------
396 What: fakephp and associated sysfs files in /sys/bus/pci/slots/
398 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
399 represent a machine's physical PCI slots. The change in semantics
400 had userspace implications, as the hotplug core no longer allowed
401 drivers to create multiple sysfs files per physical slot (required
402 for multi-function devices, e.g.). fakephp was seen as a developer's
403 tool only, and its interface changed. Too late, we learned that
404 there were some users of the fakephp interface.
406 In 2.6.30, the original fakephp interface was restored. At the same
407 time, the PCI core gained the ability that fakephp provided, namely
408 function-level hot-remove and hot-add.
410 Since the PCI core now provides the same functionality, exposed in:
413 /sys/bus/pci/devices/.../remove
414 /sys/bus/pci/devices/.../rescan
416 there is no functional reason to maintain fakephp as well.
418 We will keep the existing module so that 'modprobe fakephp' will
419 present the old /sys/bus/pci/slots/... interface for compatibility,
420 but users are urged to migrate their applications to the API above.
422 After a reasonable transition period, we will remove the legacy
424 Who: Alex Chiang <achiang@hp.com>
426 ---------------------------
428 What: CONFIG_RFKILL_INPUT
430 Why: Should be implemented in userspace, policy daemon.
431 Who: Johannes Berg <johannes@sipsolutions.net>
433 ----------------------------
435 What: sound-slot/service-* module aliases and related clutters in
438 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR
439 (14) and requests modules using custom sound-slot/service-*
440 module aliases. The only benefit of doing this is allowing
441 use of custom module aliases which might as well be considered
442 a bug at this point. This preemptive claiming prevents
443 alternative OSS implementations.
445 Till the feature is removed, the kernel will be requesting
446 both sound-slot/service-* and the standard char-major-* module
447 aliases and allow turning off the pre-claiming selectively via
448 CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss
451 After the transition phase is complete, both the custom module
452 aliases and switches to disable it will go away. This removal
453 will also allow making ALSA OSS emulation independent of
454 sound_core. The dependency will be broken then too.
455 Who: Tejun Heo <tj@kernel.org>
457 ----------------------------
459 What: Support for lcd_switch and display_get in asus-laptop driver
461 Why: These two features use non-standard interfaces. There are the
462 only features that really need multiple path to guess what's
463 the right method name on a specific laptop.
465 Removing them will allow to remove a lot of code an significantly
468 This will affect the backlight code which won't be able to know
469 if the backlight is on or off. The platform display file will also be
470 write only (like the one in eeepc-laptop).
472 This should'nt affect a lot of user because they usually know
473 when their display is on or off.
475 Who: Corentin Chary <corentin.chary@gmail.com>
477 ----------------------------
479 What: sysfs-class-rfkill state file
481 Files: net/rfkill/core.c
482 Why: Documented as obsolete since Feb 2010. This file is limited to 3
483 states while the rfkill drivers can have 4 states.
484 Who: anybody or Florian Mickler <florian@mickler.org>
486 ----------------------------
488 What: sysfs-class-rfkill claim file
490 Files: net/rfkill/core.c
491 Why: It is not possible to claim an rfkill driver since 2007. This is
492 Documented as obsolete since Feb 2010.
493 Who: anybody or Florian Mickler <florian@mickler.org>
495 ----------------------------
499 Files: drivers/isdn/capi/capifs.*
500 Why: udev fully replaces this special file system that only contains CAPI
501 NCCI TTY device nodes. User space (pppdcapiplugin) works without
502 noticing the difference.
503 Who: Jan Kiszka <jan.kiszka@web.de>
505 ----------------------------
507 What: KVM paravirt mmu host support
509 Why: The paravirt mmu host support is slower than non-paravirt mmu, both
510 on newer and older hardware. It is already not exposed to the guest,
511 and kept only for live migration purposes.
512 Who: Avi Kivity <avi@redhat.com>
514 ----------------------------
516 What: iwlwifi 50XX module parameters
518 Why: The "..50" modules parameters were used to configure 5000 series and
519 up devices; different set of module parameters also available for 4965
520 with same functionalities. Consolidate both set into single place
521 in drivers/net/wireless/iwlwifi/iwl-agn.c
523 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
525 ----------------------------
527 What: iwl4965 alias support
529 Why: Internal alias support has been present in module-init-tools for some
530 time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
533 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
535 ---------------------------
538 Files: net/netfilter/xt_NOTRACK.c
540 Why: Superseded by xt_CT
541 Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
543 ----------------------------
547 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
548 Who: Thomas Gleixner <tglx@linutronix.de>
550 ----------------------------
552 What: The acpi_sleep=s4_nonvs command line option
554 Files: arch/x86/kernel/acpi/sleep.c
555 Why: superseded by acpi_sleep=nonvs
556 Who: Rafael J. Wysocki <rjw@sisk.pl>
558 ----------------------------
560 What: PCI DMA unmap state API
562 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced
563 with DMA unmap state API (DMA unmap state API can be used for
565 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
567 ----------------------------
569 What: DMA_xxBIT_MASK macros
571 Why: DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros.
572 Who: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
574 ----------------------------
576 What: namespace cgroup (ns_cgroup)
578 Why: The ns_cgroup leads to some problems:
579 * cgroup creation is out-of-control
580 * cgroup name can conflict when pids are looping
581 * it is not possible to have a single process handling
582 a lot of namespaces without falling in a exponential creation time
583 * we may want to create a namespace without creating a cgroup
585 The ns_cgroup is replaced by a compatibility flag 'clone_children',
586 where a newly created cgroup will copy the parent cgroup values.
587 The userspace has to manually create a cgroup and add a task to
589 Who: Daniel Lezcano <daniel.lezcano@free.fr>
591 ----------------------------
593 What: iwlwifi disable_hw_scan module parameters
595 Why: Hareware scan is the prefer method for iwlwifi devices for
596 scanning operation. Remove software scan support for all the
599 Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
601 ----------------------------
603 What: access to nfsd auth cache through sys_nfsservctl or '.' files
604 in the 'nfsd' filesystem.
606 Why: This is a legacy interface which have been replaced by a more
607 dynamic cache. Continuing to maintain this interface is an
609 Who: NeilBrown <neilb@suse.de>
611 ----------------------------
615 Why: This field is deprecated. I2C device drivers shouldn't change their
616 behavior based on the underlying I2C adapter. Instead, the I2C
617 adapter driver should instantiate the I2C devices and provide the
618 needed platform-specific information.
619 Who: Jean Delvare <khali@linux-fr.org>
621 ----------------------------
623 What: cancel_rearming_delayed_work[queue]()
626 Why: The functions have been superceded by cancel_delayed_work_sync()
627 quite some time ago. The conversion is trivial and there is no
629 Who: Tejun Heo <tj@kernel.org>
631 ----------------------------
633 What: Legacy, non-standard chassis intrusion detection interface.
635 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have
636 legacy interfaces for chassis intrusion detection. A standard
637 interface has been added to each driver, so the legacy interface
639 Who: Jean Delvare <khali@linux-fr.org>
641 ----------------------------
643 What: noswapaccount kernel command line parameter
645 Why: The original implementation of memsw feature enabled by
646 CONFIG_CGROUP_MEM_RES_CTLR_SWAP could be disabled by the noswapaccount
647 kernel parameter (introduced in 2.6.29-rc1). Later on, this decision
648 turned out to be not ideal because we cannot have the feature compiled
649 in and disabled by default and let only interested to enable it
650 (e.g. general distribution kernels might need it). Therefore we have
651 added swapaccount[=0|1] parameter (introduced in 2.6.37) which provides
652 the both possibilities. If we remove noswapaccount we will have
653 less command line parameters with the same functionality and we
654 can also cleanup the parameter handling a bit ().
655 Who: Michal Hocko <mhocko@suse.cz>
657 ----------------------------