linux/drivers/base
Kay Sievers 2b2af54a5b Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev
Devtmpfs lets the kernel create a tmpfs instance called devtmpfs
very early at kernel initialization, before any driver-core device
is registered. Every device with a major/minor will provide a
device node in devtmpfs.

Devtmpfs can be changed and altered by userspace at any time,
and in any way needed - just like today's udev-mounted tmpfs.
Unmodified udev versions will run just fine on top of it, and will
recognize an already existing kernel-created device node and use it.
The default node permissions are root:root 0600. Proper permissions
and user/group ownership, meaningful symlinks, all other policy still
needs to be applied by userspace.

If a node is created by devtmps, devtmpfs will remove the device node
when the device goes away. If the device node was created by
userspace, or the devtmpfs created node was replaced by userspace, it
will no longer be removed by devtmpfs.

If it is requested to auto-mount it, it makes init=/bin/sh work
without any further userspace support. /dev will be fully populated
and dynamic, and always reflect the current device state of the kernel.
With the commonly used dynamic device numbers, it solves the problem
where static devices nodes may point to the wrong devices.

It is intended to make the initial bootup logic simpler and more robust,
by de-coupling the creation of the inital environment, to reliably run
userspace processes, from a complex userspace bootstrap logic to provide
a working /dev.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Tested-By: Harald Hoyer <harald@redhat.com>
Tested-By: Scott James Remnant <scott@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-15 09:50:49 -07:00
..
power PM: Reset transition_started at dpm_resume_noirq 2009-09-14 20:27:00 +02:00
attribute_container.c driver core: struct device - replace bus_id with dev_name(), dev_set_name() 2009-01-06 10:44:31 -08:00
base.h Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
bus.c Driver core: add new device to bus's list before probing 2009-09-15 09:50:46 -07:00
class.c Driver core: Add support for compatibility classes 2009-09-15 09:50:48 -07:00
core.c Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
cpu.c cpumask: use new cpumask_ functions in core code. 2009-03-30 22:05:16 +10:30
dd.c Driver core: move dev_get/set_drvdata to drivers/base/dd.c 2009-09-15 09:50:47 -07:00
devres.c devres: WARN() and return, don't crash on device_del() of uninitialized device 2009-07-12 13:02:09 -07:00
devtmpfs.c Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
dma-coherent.c driver-core: move dma-coherent.c from kernel to driver/base 2009-09-15 09:50:47 -07:00
dma-mapping.c devres: device resource management 2007-02-09 17:39:36 -05:00
driver.c driver model: constify attribute groups 2009-09-15 09:50:47 -07:00
firmware.c firmware: change firmware_kset to firmware_kobj 2008-01-24 20:40:23 -08:00
firmware_class.c driver core: firmware_class:fix memory leak of page pointers array 2009-07-28 13:45:22 -07:00
hypervisor.c kobject: convert /sys/hypervisor to use kobject_create 2008-01-24 20:40:15 -08:00
init.c Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
iommu.c drivers/base/iommu.c: add missing includes 2009-05-06 16:36:10 -07:00
isa.c dma-mapping: replace all DMA_24BIT_MASK macro with DMA_BIT_MASK(24) 2009-04-07 08:31:12 -07:00
Kconfig Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
Makefile Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
map.c
memory.c mm: show node to memory section relationship with symlinks in sysfs 2009-01-06 15:59:00 -08:00
module.c Driver core: move the static kobject out of struct driver 2008-01-24 20:40:35 -08:00
node.c mm: remove CONFIG_UNEVICTABLE_LRU config option 2009-06-16 19:47:42 -07:00
platform.c driver core: platform_device_add_data(): use kmemdup() 2009-09-15 09:50:48 -07:00
sys.c driver core: sysdev: do not send KOBJ_ADD uevent if kobject_init_and_add fails 2009-07-28 13:45:22 -07:00
topology.c cpumask: Use topology_core_cpumask()/topology_thread_cpumask() 2009-01-11 19:12:49 +01:00
transport_class.c SCSI: convert struct class_device to struct device 2008-04-19 19:10:33 -07:00