Documentation/feature-removal-schedule.txt

   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.
   6
   7 ---------------------------
   8
   9 What:   dev->power.power_state
  10 When:   July 2007
  11 Why:    Broken design for runtime control over driver power states, confusing
  12         driver-internal runtime power management with:  mechanisms to support
  13         system-wide sleep state transitions; event codes that distinguish
  14         different phases of swsusp "sleep" transitions; and userspace policy
  15         inputs.  This framework was never widely used, and most attempts to
  16         use it were broken.  Drivers should instead be exposing domain-specific
  17         interfaces either to kernel or to userspace.
  18 Who:    Pavel Machek <pavel@suse.cz>
  19
  20 ---------------------------
  21
  22 What:   old NCR53C9x driver
  23 When:   October 2007
  24 Why:    Replaced by the much better esp_scsi driver.  Actual low-level
  25         driver can be ported over almost trivially.
  26 Who:    David Miller <davem@davemloft.net>
  27         Christoph Hellwig <hch@lst.de>
  28
  29 ---------------------------
  30
  31 What:   Video4Linux API 1 ioctls and video_decoder.h from Video devices.
  32 When:   December 2008
  33 Files:  include/linux/video_decoder.h include/linux/videodev.h
  34 Check:  include/linux/video_decoder.h include/linux/videodev.h
  35 Why:    V4L1 AP1 was replaced by V4L2 API during migration from 2.4 to 2.6
  36         series. The old API have lots of drawbacks and don't provide enough
  37         means to work with all video and audio standards. The newer API is
  38         already available on the main drivers and should be used instead.
  39         Newer drivers should use v4l_compat_translate_ioctl function to handle
  40         old calls, replacing to newer ones.
  41         Decoder iocts are using internally to allow video drivers to
  42         communicate with video decoders. This should also be improved to allow
  43         V4L2 calls being translated into compatible internal ioctls.
  44         Compatibility ioctls will be provided, for a while, via
  45         v4l1-compat module.
  46 Who:    Mauro Carvalho Chehab <mchehab@infradead.org>
  47
  48 ---------------------------
  49
  50 What:   PCMCIA control ioctl (needed for pcmcia-cs [cardmgr, cardctl])
  51 When:   November 2005
  52 Files:  drivers/pcmcia/: pcmcia_ioctl.c
  53 Why:    With the 16-bit PCMCIA subsystem now behaving (almost) like a
  54         normal hotpluggable bus, and with it using the default kernel
  55         infrastructure (hotplug, driver core, sysfs) keeping the PCMCIA
  56         control ioctl needed by cardmgr and cardctl from pcmcia-cs is
  57         unnecessary, and makes further cleanups and integration of the
  58         PCMCIA subsystem into the Linux kernel device driver model more
  59         difficult. The features provided by cardmgr and cardctl are either
  60         handled by the kernel itself now or are available in the new
  61         pcmciautils package available at
  62         http://kernel.org/pub/linux/utils/kernel/pcmcia/
  63 Who:    Dominik Brodowski <linux@brodo.de>
  64
  65 ---------------------------
  66
  67 What:   sys_sysctl
  68 When:   September 2010
  69 Option: CONFIG_SYSCTL_SYSCALL
  70 Why:    The same information is available in a more convenient from
  71         /proc/sys, and none of the sysctl variables appear to be
  72         important performance wise.
  73
  74         Binary sysctls are a long standing source of subtle kernel
  75         bugs and security issues.
  76
  77         When I looked several months ago all I could find after
  78         searching several distributions were 5 user space programs and
  79         glibc (which falls back to /proc/sys) using this syscall.
  80
  81         The man page for sysctl(2) documents it as unusable for user
  82         space programs.
  83
  84         sysctl(2) is not generally ABI compatible to a 32bit user
  85         space application on a 64bit and a 32bit kernel.
  86
  87         For the last several months the policy has been no new binary
  88         sysctls and no one has put forward an argument to use them.
  89
  90         Binary sysctls issues seem to keep happening appearing so
  91         properly deprecating them (with a warning to user space) and a
  92         2 year grace warning period will mean eventually we can kill
  93         them and end the pain.
  94
  95         In the mean time individual binary sysctls can be dealt with
  96         in a piecewise fashion.
  97
  98 Who:    Eric Biederman <ebiederm@xmission.com>
  99
 100 ---------------------------
 101
 102 What:   remove EXPORT_SYMBOL(kernel_thread)
 103 When:   August 2006
 104 Files:  arch/*/kernel/*_ksyms.c
 105 Check:  kernel_thread
 106 Why:    kernel_thread is a low-level implementation detail.  Drivers should
 107         use the <linux/kthread.h> API instead which shields them from
 108         implementation details and provides a higherlevel interface that
 109         prevents bugs and code duplication
 110 Who:    Christoph Hellwig <hch@lst.de>
 111
 112 ---------------------------
 113
 114 What:   eepro100 network driver
 115 When:   January 2007
 116 Why:    replaced by the e100 driver
 117 Who:    Adrian Bunk <bunk@stusta.de>
 118
 119 ---------------------------
 120
 121 What:   Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
 122         (temporary transition config option provided until then)
 123         The transition config option will also be removed at the same time.
 124 When:   before 2.6.19
 125 Why:    Unused symbols are both increasing the size of the kernel binary
 126         and are often a sign of "wrong API"
 127 Who:    Arjan van de Ven <arjan@linux.intel.com>
 128
 129 ---------------------------
 130
 131 What:   PHYSDEVPATH, PHYSDEVBUS, PHYSDEVDRIVER in the uevent environment
 132 When:   October 2008
 133 Why:    The stacking of class devices makes these values misleading and
 134         inconsistent.
 135         Class devices should not carry any of these properties, and bus
 136         devices have SUBSYTEM and DRIVER as a replacement.
 137 Who:    Kay Sievers <kay.sievers@suse.de>
 138
 139 ---------------------------
 140
 141 What:   find_task_by_pid
 142 When:   2.6.26
 143 Why:    With pid namespaces, calling this funciton will return the
 144         wrong task when called from inside a namespace.
 145
 146         The best way to save a task pid and find a task by this
 147         pid later, is to find this task's struct pid pointer (or get
 148         it directly from the task) and call pid_task() later.
 149
 150         If someone really needs to get a task by its pid_t, then
 151         he most likely needs the find_task_by_vpid() to get the
 152         task from the same namespace as the current task is in, but
 153         this may be not so in general.
 154
 155 Who:    Pavel Emelyanov <xemul@openvz.org>
 156
 157 ---------------------------
 158
 159 What:   ACPI procfs interface
 160 When:   July 2008
 161 Why:    ACPI sysfs conversion should be finished by January 2008.
 162         ACPI procfs interface will be removed in July 2008 so that
 163         there is enough time for the user space to catch up.
 164 Who:    Zhang Rui <rui.zhang@intel.com>
 165
 166 ---------------------------
 167
 168 What:   /proc/acpi/button
 169 When:   August 2007
 170 Why:    /proc/acpi/button has been replaced by events to the input layer
 171         since 2.6.20.
 172 Who:    Len Brown <len.brown@intel.com>
 173
 174 ---------------------------
 175
 176 What:   /proc/acpi/event
 177 When:   February 2008
 178 Why:    /proc/acpi/event has been replaced by events via the input layer
 179         and netlink since 2.6.23.
 180 Who:    Len Brown <len.brown@intel.com>
 181
 182 ---------------------------
 183
 184 What: libata spindown skipping and warning
 185 When: Dec 2008
 186 Why:  Some halt(8) implementations synchronize caches for and spin
 187       down libata disks because libata didn't use to spin down disk on
 188       system halt (only synchronized caches).
 189       Spin down on system halt is now implemented.  sysfs node
 190       /sys/class/scsi_disk/h:c:i:l/manage_start_stop is present if
 191       spin down support is available.
 192       Because issuing spin down command to an already spun down disk
 193       makes some disks spin up just to spin down again, libata tracks
 194       device spindown status to skip the extra spindown command and
 195       warn about it.
 196       This is to give userspace tools the time to get updated and will
 197       be removed after userspace is reasonably updated.
 198 Who:  Tejun Heo <htejun@gmail.com>
 199
 200 ---------------------------
 201
 202 What: The arch/ppc and include/asm-ppc directories
 203 When: Jun 2008
 204 Why:  The arch/powerpc tree is the merged architecture for ppc32 and ppc64
 205       platforms.  Currently there are efforts underway to port the remaining
 206       arch/ppc platforms to the merged tree.  New submissions to the arch/ppc
 207       tree have been frozen with the 2.6.22 kernel release and that tree will
 208       remain in bug-fix only mode until its scheduled removal.  Platforms
 209       that are not ported by June 2008 will be removed due to the lack of an
 210       interested maintainer.
 211 Who:  linuxppc-dev@ozlabs.org
 212
 213 ---------------------------
 214
 215 What:   i386/x86_64 bzImage symlinks
 216 When:   April 2010
 217
 218 Why:    The i386/x86_64 merge provides a symlink to the old bzImage
 219         location so not yet updated user space tools, e.g. package
 220         scripts, do not break.
 221 Who:    Thomas Gleixner <tglx@linutronix.de>
 222
 223 ---------------------------
 224
 225 What:   i2c-i810, i2c-prosavage and i2c-savage4
 226 When:   May 2008
 227 Why:    These drivers are superseded by i810fb, intelfb and savagefb.
 228 Who:    Jean Delvare <khali@linux-fr.org>
 229
 230 ---------------------------
 231
 232 What (Why):
 233         - include/linux/netfilter_ipv4/ipt_TOS.h ipt_tos.h header files
 234           (superseded by xt_TOS/xt_tos target & match)
 235
 236         - "forwarding" header files like ipt_mac.h in
 237           include/linux/netfilter_ipv4/ and include/linux/netfilter_ipv6/
 238
 239         - xt_CONNMARK match revision 0
 240           (superseded by xt_CONNMARK match revision 1)
 241
 242         - xt_MARK target revisions 0 and 1
 243           (superseded by xt_MARK match revision 2)
 244
 245         - xt_connmark match revision 0
 246           (superseded by xt_connmark match revision 1)
 247
 248         - xt_conntrack match revision 0
 249           (superseded by xt_conntrack match revision 1)
 250
 251         - xt_iprange match revision 0,
 252           include/linux/netfilter_ipv4/ipt_iprange.h
 253           (superseded by xt_iprange match revision 1)
 254
 255         - xt_mark match revision 0
 256           (superseded by xt_mark match revision 1)
 257
 258 When:   January 2009 or Linux 2.7.0, whichever comes first
 259 Why:    Superseded by newer revisions or modules
 260 Who:    Jan Engelhardt <jengelh@computergmbh.de>
 261
 262 ---------------------------
 263
 264 What:   b43 support for firmware revision < 410
 265 When:   July 2008
 266 Why:    The support code for the old firmware hurts code readability/maintainability
 267         and slightly hurts runtime performance. Bugfixes for the old firmware
 268         are not provided by Broadcom anymore.
 269 Who:    Michael Buesch <mb@bu3sch.de>
 270
 271 ---------------------------
 272
 273 What:   init_mm export
 274 When:   2.6.26
 275 Why:    Not used in-tree. The current out-of-tree users used it to
 276         work around problems in the CPA code which should be resolved
 277         by now. One usecase was described to provide verification code
 278         of the CPA operation. That's a good idea in general, but such
 279         code / infrastructure should be in the kernel and not in some
 280         out-of-tree driver.
 281 Who:    Thomas Gleixner <tglx@linutronix.de>
 282
 283 ----------------------------
 284
 285 What:   usedac i386 kernel parameter
 286 When:   2.6.27
 287 Why:    replaced by allowdac and no dac combination
 288 Who:    Glauber Costa <gcosta@redhat.com>
 289
 290 ---------------------------
 291
 292 What:   old style serial driver for ColdFire (CONFIG_SERIAL_COLDFIRE)
 293 When:   2.6.28
 294 Why:    This driver still uses the old interface and has been replaced
 295         by CONFIG_SERIAL_MCF.
 296 Who:    Sebastian Siewior <sebastian@breakpoint.cc>
 297
 298 ---------------------------
 299
 300 What:   /sys/o2cb symlink
 301 When:   January 2010
 302 Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
 303         exists as a symlink for backwards compatibility for old versions of
 304         ocfs2-tools. 2 years should be sufficient time to phase in new versions
 305         which know to look in /sys/fs/o2cb.
 306 Who:    ocfs2-devel@oss.oracle.com
 307
 308 ---------------------------
 309
 310 What:   asm/semaphore.h
 311 When:   2.6.26
 312 Why:    Implementation became generic; users should now include
 313         linux/semaphore.h instead.
 314 Who:    Matthew Wilcox <willy@linux.intel.com>