UdevRoadmap
Launchpad Entry: https://launchpad.net/distros/ubuntu/+spec/foo
Created: Date(2005-11-02T17:22:51Z) by JeffBailey
Contributors: JeffBailey
Packages affected:
Summary
Upgrading from udev 060 to 071 is a major change that affects initramfs, udev, hotplug, hal, and many other pieces. The 2.6.15 kernel will require udev 071. Because these changes are invasive, this spec is split out from HardwareDetection to make sure that it can be reviewed and implemented independantly.
Rationale
Many components of the Linux system will require a newer udev. These include ProbeForRootFilesystem, LinuxKernelRoadmap, and HardwareDetection.
Scope
Newer versions of udev affect the following packages:
- initramfs-tools
- hotplug
- klibc
- hal
- linux-image-*
Implementation
initramfs
Update the initramfs startup sequence to reflect the following:
* Create base device nodes * Touch /dev/.udev_scoreboard * Start udevd * Load modules from /etc/mkinitramfs/modules (and other force_load calls)
Note: without udevstart, something needs to correct permissions, or we need to provide the rules.
* Walk the sysfs tree for harddrive devices and tickle uevents for those * Walk the ide, scsi, and i2o busses * Attempt hibernate recovery * Walk the pci sysfs tree for usb controllers
udev
* Upgrade to at least udev-071. * Add scoreboard to udevd
full userspace init scripts
* Where udevstart and coldplugging routines are currently run, ensure that udevd is running (in case of custom kernels), and pass over entire sysfs tree to cause events to be rerun. This will ensure that device nodes are created with correct permissions and according to the rules of the running system.
Code
The scoreboading component will need to be written. initramfs-tools needs to be modified to handle event driven coldplugging.
Data preservation and migration
Custom written hotplug rules will need to be migrated to be udev rules. There is no way to do this in an automated fashion.