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linux/Documentation/feature-removal-schedule.txt
Eric W. Biederman 13bb7e37e5 [PATCH] sysctl: Undeprecate sys_sysctl 
The basic issue is that despite have been deprecated and warned about as a
very bad thing in the man pages since its inception there are a few real
users of sys_sysctl.  It was my assumption that because sysctl had been
deprecated for all of 2.6 there would be no user space users by this point,
so I initially gave sys_sysctl a very short deprecation period.

Now that I know there are a few real users the only sane way to proceed
with deprecation is to push the time limit out to a year or two work and
work with distributions that have big testing pools like fedora core to
find these last remaining users.

Which means that the sys_sysctl interface needs to be maintained in the
meantime.

Since I have provided a technical measure that allows us to add new sysctl
entries without reserving more binary numbers I believe that is enough to
fix the sys_sysctl binary interface maintenance problems, because there is
no longer a need to change the binary interface at all.

Since the sys_sysctl implementation needs to stay around for a while and
the worst of the maintenance issues that caused us to occasionally break
the ABI have been addressed I don't see any advantage in continuing with
the removal of sys_sysctl.

So instead of merely increasing the deprecation period this patch removes
the deprecation of sys_sysctl and modifies the kernel to compile the code
in by default.

With committing to maintain sys_sysctl we get all of the advantages of a
fast interface for anything that needs it.  Currently sys_sysctl is about
5x faster than /proc/sys, for the same string data.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-08 18:29:24 -08:00

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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: /sys/devices/.../power/state
dev->power.power_state
dpm_runtime_{suspend,resume)()
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 <pavel@suse.cz>
---------------------------
What: RAW driver (CONFIG_RAW_DRIVER)
When: December 2005
Why: declared obsolete since kernel 2.6.3
O_DIRECT can be used instead
Who: Adrian Bunk <bunk@stusta.de>
---------------------------
What: raw1394: requests of type RAW1394_REQ_ISO_SEND, RAW1394_REQ_ISO_LISTEN
When: November 2006
Why: Deprecated in favour of the new ioctl-based rawiso interface, which is
more efficient. You should really be using libraw1394 for raw1394
access anyway.
Who: Jody McIntyre <scjody@modernduck.com>
---------------------------
What: Video4Linux API 1 ioctls and video_decoder.h from Video devices.
When: December 2006
Why: V4L1 AP1 was replaced by V4L2 API. during migration from 2.4 to 2.6
series. The old API have lots of drawbacks and don't provide enough
means to work with all video and audio standards. The newer API is
already available on the main drivers and should be used instead.
Newer drivers should use v4l_compat_translate_ioctl function to handle
old calls, replacing to newer ones.
Decoder iocts are using internally to allow video drivers to
communicate with video decoders. This should also be improved to allow
V4L2 calls being translated into compatible internal ioctls.
Who: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
---------------------------
What: PCMCIA control ioctl (needed for pcmcia-cs [cardmgr, cardctl])
When: November 2005
Files: drivers/pcmcia/: pcmcia_ioctl.c
Why: With the 16-bit PCMCIA subsystem now behaving (almost) like a
normal hotpluggable bus, and with it using the default kernel
infrastructure (hotplug, driver core, sysfs) keeping the PCMCIA
control ioctl needed by cardmgr and cardctl from pcmcia-cs is
unnecessary, and makes further cleanups and integration of the
PCMCIA subsystem into the Linux kernel device driver model more
difficult. The features provided by cardmgr and cardctl are either
handled by the kernel itself now or are available in the new
pcmciautils package available at
http://kernel.org/pub/linux/utils/kernel/pcmcia/
Who: Dominik Brodowski <linux@brodo.de>
---------------------------
What: ip_queue and ip6_queue (old ipv4-only and ipv6-only netfilter queue)
When: December 2005
Why: This interface has been obsoleted by the new layer3-independent
"nfnetlink_queue". The Kernel interface is compatible, so the old
ip[6]tables "QUEUE" targets still work and will transparently handle
all packets into nfnetlink queue number 0. Userspace users will have
to link against API-compatible library on top of libnfnetlink_queue
instead of the current 'libipq'.
Who: Harald Welte <laforge@netfilter.org>
---------------------------
What: remove EXPORT_SYMBOL(kernel_thread)
When: August 2006
Files: arch/*/kernel/*_ksyms.c
Why: kernel_thread is a low-level implementation detail. Drivers should
use the <linux/kthread.h> API instead which shields them from
implementation details and provides a higherlevel interface that
prevents bugs and code duplication
Who: Christoph Hellwig <hch@lst.de>
---------------------------
What: CONFIG_FORCED_INLINING
When: June 2006
Why: Config option is there to see if gcc is good enough. (in january
2006). If it is, the behavior should just be the default. If it's not,
the option should just go away entirely.
Who: Arjan van de Ven
---------------------------
What: eepro100 network driver
When: January 2007
Why: replaced by the e100 driver
Who: Adrian Bunk <bunk@stusta.de>
---------------------------
What: drivers depending on OSS_OBSOLETE_DRIVER
When: options in 2.6.20, code in 2.6.22
Why: OSS drivers with ALSA replacements
Who: Adrian Bunk <bunk@stusta.de>
---------------------------
What: pci_module_init(driver)
When: January 2007
Why: Is replaced by pci_register_driver(pci_driver).
Who: Richard Knutsson <ricknu-0@student.ltu.se> and Greg Kroah-Hartman <gregkh@suse.de>
---------------------------
What: Usage of invalid timevals in setitimer
When: March 2007
Why: POSIX requires to validate timevals in the setitimer call. This
was never done by Linux. The invalid (e.g. negative timevals) were
silently converted to more or less random timeouts and intervals.
Until the removal a per boot limited number of warnings is printed
and the timevals are sanitized.
Who: Thomas Gleixner <tglx@linutronix.de>
---------------------------
What: I2C interface of the it87 driver
When: January 2007
Why: The ISA interface is faster and should be always available. The I2C
probing is also known to cause trouble in at least one case (see
bug #5889.)
Who: Jean Delvare <khali@linux-fr.org>
---------------------------
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 <arjan@linux.intel.com>
---------------------------
What: mount/umount uevents
When: February 2007
Why: These events are not correct, and do not properly let userspace know
when a file system has been mounted or unmounted. Userspace should
poll the /proc/mounts file instead to detect this properly.
Who: Greg Kroah-Hartman <gregkh@suse.de>
---------------------------
What: USB driver API moves to EXPORT_SYMBOL_GPL
When: February 2008
Files: include/linux/usb.h, drivers/usb/core/driver.c
Why: The USB subsystem has changed a lot over time, and it has been
possible to create userspace USB drivers using usbfs/libusb/gadgetfs
that operate as fast as the USB bus allows. Because of this, the USB
subsystem will not be allowing closed source kernel drivers to
register with it, after this grace period is over. If anyone needs
any help in converting their closed source drivers over to use the
userspace filesystems, please contact the
linux-usb-devel@lists.sourceforge.net mailing list, and the developers
there will be glad to help you out.
Who: Greg Kroah-Hartman <gregkh@suse.de>
---------------------------
What: find_trylock_page
When: January 2007
Why: The interface no longer has any callers left in the kernel. It
is an odd interface (compared with other find_*_page functions), in
that it does not take a refcount to the page, only the page lock.
It should be replaced with find_get_page or find_lock_page if possible.
This feature removal can be reevaluated if users of the interface
cannot cleanly use something else.
Who: Nick Piggin <npiggin@suse.de>
---------------------------
What: Interrupt only SA_* flags
When: Januar 2007
Why: The interrupt related SA_* flags are replaced by IRQF_* to move them
out of the signal namespace.
Who: Thomas Gleixner <tglx@linutronix.de>
---------------------------
What: i2c-ite and i2c-algo-ite drivers
When: September 2006
Why: These drivers never compiled since they were added to the kernel
tree 5 years ago. This feature removal can be reevaluated if
someone shows interest in the drivers, fixes them and takes over
maintenance.
http://marc.theaimsgroup.com/?l=linux-mips&m=115040510817448
Who: Jean Delvare <khali@linux-fr.org>
---------------------------
What: Bridge netfilter deferred IPv4/IPv6 output hook calling
When: January 2007
Why: The deferred output hooks are a layering violation causing unusual
and broken behaviour on bridge devices. Examples of things they
break include QoS classifation using the MARK or CLASSIFY targets,
the IPsec policy match and connection tracking with VLANs on a
bridge. Their only use is to enable bridge output port filtering
within iptables with the physdev match, which can also be done by
combining iptables and ebtables using netfilter marks. Until it
will get removed the hook deferral is disabled by default and is
only enabled when needed.
Who: Patrick McHardy <kaber@trash.net>
---------------------------
What: frame diverter
When: November 2006
Why: The frame diverter is included in most distribution kernels, but is
broken. It does not correctly handle many things:
- IPV6
- non-linear skb's
- network device RCU on removal
- input frames not correctly checked for protocol errors
It also adds allocation overhead even if not enabled.
It is not clear if anyone is still using it.
Who: Stephen Hemminger <shemminger@osdl.org>
---------------------------
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 <kay.sievers@suse.de>
---------------------------
What: i2c-isa
When: December 2006
Why: i2c-isa is a non-sense and doesn't fit in the device driver
model. Drivers relying on it are better implemented as platform
drivers.
Who: Jean Delvare <khali@linux-fr.org>
---------------------------
What: ftape
When: 2.6.20
Why: Orphaned for ages. SMP bugs long unfixed. Few users left
in the world.
Who: Jeff Garzik <jeff@garzik.org>
---------------------------
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