The following is a list of files and features that are going to be removed in the kernel source tree. Every entry should contain what exactly is going away, why it is happening, and who is going to be doing the work. When the feature is removed from the kernel, it should also be removed from this file. --------------------------- What: PRISM54 When: 2.6.34 Why: prism54 FullMAC PCI / Cardbus devices used to be supported only by the prism54 wireless driver. After Intersil stopped selling these devices in preference for the newer more flexible SoftMAC devices a SoftMAC device driver was required and prism54 did not support them. The p54pci driver now exists and has been present in the kernel for a while. This driver supports both SoftMAC devices and FullMAC devices. The main difference between these devices was the amount of memory which could be used for the firmware. The SoftMAC devices support a smaller amount of memory. Because of this the SoftMAC firmware fits into FullMAC devices's memory. p54pci supports not only PCI / Cardbus but also USB and SPI. Since p54pci supports all devices prism54 supports you will have a conflict. I'm not quite sure how distributions are handling this conflict right now. prism54 was kept around due to claims users may experience issues when using the SoftMAC driver. Time has passed users have not reported issues. If you use prism54 and for whatever reason you cannot use p54pci please let us know! E-mail us at: linux-wireless@vger.kernel.org For more information see the p54 wiki page: http://wireless.kernel.org/en/users/Drivers/p54 Who: Luis R. Rodriguez --------------------------- What: AR9170USB When: 2.6.40 Why: This driver is deprecated and the firmware is no longer maintained. The replacement driver "carl9170" has been around for a while, so the devices are still supported. Who: Christian Lamparter --------------------------- What: IRQF_SAMPLE_RANDOM Check: IRQF_SAMPLE_RANDOM When: July 2009 Why: Many of IRQF_SAMPLE_RANDOM users are technically bogus as entropy sources in the kernel's current entropy model. To resolve this, every input point to the kernel's entropy pool needs to better document the type of entropy source it actually is. This will be replaced with additional add_*_randomness functions in drivers/char/random.c Who: Robin Getz & Matt Mackall --------------------------- What: Deprecated snapshot ioctls When: 2.6.36 Why: The ioctls in kernel/power/user.c were marked as deprecated long time ago. Now they notify users about that so that they need to replace their userspace. After some more time, remove them completely. Who: Jiri Slaby --------------------------- What: The ieee80211_regdom module parameter When: March 2010 / desktop catchup Why: This was inherited by the CONFIG_WIRELESS_OLD_REGULATORY code, and currently serves as an option for users to define an ISO / IEC 3166 alpha2 code for the country they are currently present in. Although there are userspace API replacements for this through nl80211 distributions haven't yet caught up with implementing decent alternatives through standard GUIs. Although available as an option through iw or wpa_supplicant its just a matter of time before distributions pick up good GUI options for this. The ideal solution would actually consist of intelligent designs which would do this for the user automatically even when travelling through different countries. Until then we leave this module parameter as a compromise. When userspace improves with reasonable widely-available alternatives for this we will no longer need this module parameter. This entry hopes that by the super-futuristically looking date of "March 2010" we will have such replacements widely available. Who: Luis R. Rodriguez --------------------------- What: dev->power.power_state When: July 2007 Why: Broken design for runtime control over driver power states, confusing driver-internal runtime power management with: mechanisms to support system-wide sleep state transitions; event codes that distinguish different phases of swsusp "sleep" transitions; and userspace policy inputs. This framework was never widely used, and most attempts to use it were broken. Drivers should instead be exposing domain-specific interfaces either to kernel or to userspace. Who: Pavel Machek --------------------------- What: sys_sysctl When: September 2010 Option: CONFIG_SYSCTL_SYSCALL Why: The same information is available in a more convenient from /proc/sys, and none of the sysctl variables appear to be important performance wise. Binary sysctls are a long standing source of subtle kernel bugs and security issues. When I looked several months ago all I could find after searching several distributions were 5 user space programs and glibc (which falls back to /proc/sys) using this syscall. The man page for sysctl(2) documents it as unusable for user space programs. sysctl(2) is not generally ABI compatible to a 32bit user space application on a 64bit and a 32bit kernel. For the last several months the policy has been no new binary sysctls and no one has put forward an argument to use them. Binary sysctls issues seem to keep happening appearing so properly deprecating them (with a warning to user space) and a 2 year grace warning period will mean eventually we can kill them and end the pain. In the mean time individual binary sysctls can be dealt with in a piecewise fashion. Who: Eric Biederman --------------------------- What: /proc//oom_adj When: August 2012 Why: /proc//oom_adj allows userspace to influence the oom killer's badness heuristic used to determine which task to kill when the kernel is out of memory. The badness heuristic has since been rewritten since the introduction of this tunable such that its meaning is deprecated. The value was implemented as a bitshift on a score generated by the badness() function that did not have any precise units of measure. With the rewrite, the score is given as a proportion of available memory to the task allocating pages, so using a bitshift which grows the score exponentially is, thus, impossible to tune with fine granularity. A much more powerful interface, /proc//oom_score_adj, was introduced with the oom killer rewrite that allows users to increase or decrease the badness() score linearly. This interface will replace /proc//oom_adj. A warning will be emitted to the kernel log if an application uses this deprecated interface. After it is printed once, future warnings will be suppressed until the kernel is rebooted. --------------------------- What: CS5535/CS5536 obsolete GPIO driver When: June 2011 Files: drivers/staging/cs5535_gpio/* Check: drivers/staging/cs5535_gpio/cs5535_gpio.c Why: A newer driver replaces this; it is drivers/gpio/cs5535-gpio.c, and integrates with the Linux GPIO subsystem. The old driver has been moved to staging, and will be removed altogether around 2.6.40. Please test the new driver, and ensure that the functionality you need and any bugfixes from the old driver are available in the new one. Who: Andres Salomon -------------------------- What: remove EXPORT_SYMBOL(kernel_thread) When: August 2006 Files: arch/*/kernel/*_ksyms.c Check: kernel_thread Why: kernel_thread is a low-level implementation detail. Drivers should use the API instead which shields them from implementation details and provides a higherlevel interface that prevents bugs and code duplication Who: Christoph Hellwig --------------------------- What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports (temporary transition config option provided until then) The transition config option will also be removed at the same time. When: before 2.6.19 Why: Unused symbols are both increasing the size of the kernel binary and are often a sign of "wrong API" Who: Arjan van de Ven --------------------------- What: PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment When: October 2008 Why: The stacking of class devices makes these values misleading and inconsistent. Class devices should not carry any of these properties, and bus devices have SUBSYTEM and DRIVER as a replacement. Who: Kay Sievers --------------------------- What: ACPI procfs interface When: July 2008 Why: ACPI sysfs conversion should be finished by January 2008. ACPI procfs interface will be removed in July 2008 so that there is enough time for the user space to catch up. Who: Zhang Rui --------------------------- What: CONFIG_ACPI_PROCFS_POWER When: 2.6.39 Why: sysfs I/F for ACPI power devices, including AC and Battery, has been working in upstream kenrel since 2.6.24, Sep 2007. In 2.6.37, we make the sysfs I/F always built in and this option disabled by default. Remove this option and the ACPI power procfs interface in 2.6.39. Who: Zhang Rui --------------------------- What: /proc/acpi/event When: February 2008 Why: /proc/acpi/event has been replaced by events via the input layer and netlink since 2.6.23. Who: Len Brown --------------------------- What: i386/x86_64 bzImage symlinks When: April 2010 Why: The i386/x86_64 merge provides a symlink to the old bzImage location so not yet updated user space tools, e.g. package scripts, do not break. Who: Thomas Gleixner --------------------------- What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib When: February 2010 Why: All callers should use explicit gpio_request()/gpio_free(). The autorequest mechanism in gpiolib was provided mostly as a migration aid for legacy GPIO interfaces (for SOC based GPIOs). Those users have now largely migrated. Platforms implementing the GPIO interfaces without using gpiolib will see no changes. Who: David Brownell --------------------------- What: b43 support for firmware revision < 410 When: The schedule was July 2008, but it was decided that we are going to keep the code as long as there are no major maintanance headaches. So it _could_ be removed _any_ time now, if it conflicts with something new. Why: The support code for the old firmware hurts code readability/maintainability and slightly hurts runtime performance. Bugfixes for the old firmware are not provided by Broadcom anymore. Who: Michael Buesch --------------------------- What: /sys/o2cb symlink When: January 2010 Why: /sys/fs/o2cb is the proper location for this information - /sys/o2cb exists as a symlink for backwards compatibility for old versions of ocfs2-tools. 2 years should be sufficient time to phase in new versions which know to look in /sys/fs/o2cb. Who: ocfs2-devel@oss.oracle.com --------------------------- What: Ability for non root users to shm_get hugetlb pages based on mlock resource limits When: 2.6.31 Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or have CAP_IPC_LOCK to be able to allocate shm segments backed by huge pages. The mlock based rlimit check to allow shm hugetlb is inconsistent with mmap based allocations. Hence it is being deprecated. Who: Ravikiran Thirumalai --------------------------- What: CONFIG_THERMAL_HWMON When: January 2009 Why: This option was introduced just to allow older lm-sensors userspace to keep working over the upgrade to 2.6.26. At the scheduled time of removal fixed lm-sensors (2.x or 3.x) should be readily available. Who: Rene Herman --------------------------- What: Code that is now under CONFIG_WIRELESS_EXT_SYSFS (in net/core/net-sysfs.c) When: After the only user (hal) has seen a release with the patches for enough time, probably some time in 2010. Why: Over 1K .text/.data size reduction, data is available in other ways (ioctls) Who: Johannes Berg --------------------------- What: sysfs ui for changing p4-clockmod parameters When: September 2009 Why: See commits 129f8ae9b1b5be94517da76009ea956e89104ce8 and e088e4c9cdb618675874becb91b2fd581ee707e6. Removal is subject to fixing any remaining bugs in ACPI which may cause the thermal throttling not to happen at the right time. Who: Dave Jones , Matthew Garrett ----------------------------- What: fakephp and associated sysfs files in /sys/bus/pci/slots/ When: 2011 Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to represent a machine's physical PCI slots. The change in semantics had userspace implications, as the hotplug core no longer allowed drivers to create multiple sysfs files per physical slot (required for multi-function devices, e.g.). fakephp was seen as a developer's tool only, and its interface changed. Too late, we learned that there were some users of the fakephp interface. In 2.6.30, the original fakephp interface was restored. At the same time, the PCI core gained the ability that fakephp provided, namely function-level hot-remove and hot-add. Since the PCI core now provides the same functionality, exposed in: /sys/bus/pci/rescan /sys/bus/pci/devices/.../remove /sys/bus/pci/devices/.../rescan there is no functional reason to maintain fakephp as well. We will keep the existing module so that 'modprobe fakephp' will present the old /sys/bus/pci/slots/... interface for compatibility, but users are urged to migrate their applications to the API above. After a reasonable transition period, we will remove the legacy fakephp interface. Who: Alex Chiang --------------------------- What: CONFIG_RFKILL_INPUT When: 2.6.33 Why: Should be implemented in userspace, policy daemon. Who: Johannes Berg ---------------------------- What: sound-slot/service-* module aliases and related clutters in sound/sound_core.c When: August 2010 Why: OSS sound_core grabs all legacy minors (0-255) of SOUND_MAJOR (14) and requests modules using custom sound-slot/service-* module aliases. The only benefit of doing this is allowing use of custom module aliases which might as well be considered a bug at this point. This preemptive claiming prevents alternative OSS implementations. Till the feature is removed, the kernel will be requesting both sound-slot/service-* and the standard char-major-* module aliases and allow turning off the pre-claiming selectively via CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel parameter. After the transition phase is complete, both the custom module aliases and switches to disable it will go away. This removal will also allow making ALSA OSS emulation independent of sound_core. The dependency will be broken then too. Who: Tejun Heo ---------------------------- What: Support for lcd_switch and display_get in asus-laptop driver When: March 2010 Why: These two features use non-standard interfaces. There are the only features that really need multiple path to guess what's the right method name on a specific laptop. Removing them will allow to remove a lot of code an significantly clean the drivers. This will affect the backlight code which won't be able to know if the backlight is on or off. The platform display file will also be write only (like the one in eeepc-laptop). This should'nt affect a lot of user because they usually know when their display is on or off. Who: Corentin Chary ---------------------------- What: sysfs-class-rfkill state file When: Feb 2014 Files: net/rfkill/core.c Why: Documented as obsolete since Feb 2010. This file is limited to 3 states while the rfkill drivers can have 4 states. Who: anybody or Florian Mickler ---------------------------- What: sysfs-class-rfkill claim file When: Feb 2012 Files: net/rfkill/core.c Why: It is not possible to claim an rfkill driver since 2007. This is Documented as obsolete since Feb 2010. Who: anybody or Florian Mickler ---------------------------- What: KVM paravirt mmu host support When: January 2011 Why: The paravirt mmu host support is slower than non-paravirt mmu, both on newer and older hardware. It is already not exposed to the guest, and kept only for live migration purposes. Who: Avi Kivity ---------------------------- What: iwlwifi 50XX module parameters When: 2.6.40 Why: The "..50" modules parameters were used to configure 5000 series and up devices; different set of module parameters also available for 4965 with same functionalities. Consolidate both set into single place in drivers/net/wireless/iwlwifi/iwl-agn.c Who: Wey-Yi Guy ---------------------------- What: iwl4965 alias support When: 2.6.40 Why: Internal alias support has been present in module-init-tools for some time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed with no impact. Who: Wey-Yi Guy --------------------------- What: xt_NOTRACK Files: net/netfilter/xt_NOTRACK.c When: April 2011 Why: Superseded by xt_CT Who: Netfilter developer team ---------------------------- What: IRQF_DISABLED When: 2.6.36 Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled Who: Thomas Gleixner ---------------------------- What: The acpi_sleep=s4_nonvs command line option When: 2.6.37 Files: arch/x86/kernel/acpi/sleep.c Why: superseded by acpi_sleep=nonvs Who: Rafael J. Wysocki ---------------------------- What: PCI DMA unmap state API When: August 2012 Why: PCI DMA unmap state API (include/linux/pci-dma.h) was replaced with DMA unmap state API (DMA unmap state API can be used for any bus). Who: FUJITA Tomonori ---------------------------- What: DMA_xxBIT_MASK macros When: Jun 2011 Why: DMA_xxBIT_MASK macros were replaced with DMA_BIT_MASK() macros. Who: FUJITA Tomonori ---------------------------- What: namespace cgroup (ns_cgroup) When: 2.6.38 Why: The ns_cgroup leads to some problems: * cgroup creation is out-of-control * cgroup name can conflict when pids are looping * it is not possible to have a single process handling a lot of namespaces without falling in a exponential creation time * we may want to create a namespace without creating a cgroup The ns_cgroup is replaced by a compatibility flag 'clone_children', where a newly created cgroup will copy the parent cgroup values. The userspace has to manually create a cgroup and add a task to the 'tasks' file. Who: Daniel Lezcano ---------------------------- What: iwlwifi disable_hw_scan module parameters When: 2.6.40 Why: Hareware scan is the prefer method for iwlwifi devices for scanning operation. Remove software scan support for all the iwlwifi devices. Who: Wey-Yi Guy ---------------------------- What: access to nfsd auth cache through sys_nfsservctl or '.' files in the 'nfsd' filesystem. When: 2.6.40 Why: This is a legacy interface which have been replaced by a more dynamic cache. Continuing to maintain this interface is an unnecessary burden. Who: NeilBrown ---------------------------- What: cancel_rearming_delayed_work[queue]() When: 2.6.39 Why: The functions have been superceded by cancel_delayed_work_sync() quite some time ago. The conversion is trivial and there is no in-kernel user left. Who: Tejun Heo ---------------------------- What: Legacy, non-standard chassis intrusion detection interface. When: June 2011 Why: The adm9240, w83792d and w83793 hardware monitoring drivers have legacy interfaces for chassis intrusion detection. A standard interface has been added to each driver, so the legacy interface can be removed. Who: Jean Delvare ---------------------------- What: xt_connlimit rev 0 When: 2012 Who: Jan Engelhardt Files: net/netfilter/xt_connlimit.c ---------------------------- What: noswapaccount kernel command line parameter When: 2.6.40 Why: The original implementation of memsw feature enabled by CONFIG_CGROUP_MEM_RES_CTLR_SWAP could be disabled by the noswapaccount kernel parameter (introduced in 2.6.29-rc1). Later on, this decision turned out to be not ideal because we cannot have the feature compiled in and disabled by default and let only interested to enable it (e.g. general distribution kernels might need it). Therefore we have added swapaccount[=0|1] parameter (introduced in 2.6.37) which provides the both possibilities. If we remove noswapaccount we will have less command line parameters with the same functionality and we can also cleanup the parameter handling a bit (). Who: Michal Hocko ---------------------------- What: ipt_addrtype match include file When: 2012 Why: superseded by xt_addrtype Who: Florian Westphal Files: include/linux/netfilter_ipv4/ipt_addrtype.h ---------------------------- What: i2c_driver.attach_adapter i2c_driver.detach_adapter When: September 2011 Why: These legacy callbacks should no longer be used as i2c-core offers a variety of preferable alternative ways to instantiate I2C devices. Who: Jean Delvare ----------------------------