UdevRoadmap

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Revision 14 as of 2005-11-05 16:54:00
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''' Note: The Ubuntu kernel doesn't not reliably supporting resuming from hibernate with removable devices. '''
''' Note: The Ubuntu kernel doesn't reliably support resuming from hibernate with removable devices. '''
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 * Restart udevd, or at least instruct it to change its inotify watch on rules.
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 * Make sure hotplug is cleaned away in postinst, moving the init script to .dpkg-old, etc.
 * Move the existing isapnp maps from hotplug and put them in udev. Continue to update them as we discover more devices that need to go in.
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 * Move the existing isapnp maps from hotplug and put them in udev. Continue to update them as we discover more devices that need to go in.

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

Scope

This is an implementation for Dapper.

Newer versions of udev affect the following packages:

  • initramfs-tools
  • hotplug
  • klibc
  • hal
  • linux-image-*
  • modutils

Implementation

initramfs

Update the initramfs startup sequence to reflect the following:

  • Create base device nodes
  • 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 pci sysfs tree for harddrive devices and tickle uevents for those.
  • Walk the ide, scsi, and i2o busses
  • Attempt hibernate recovery

Note: The Ubuntu kernel doesn't reliably support resuming from hibernate with removable devices.

  • Walk the pci sysfs tree for usb and ieee1394 controllers
  • Walk the ide, scsi, and i2o busses again for root devices on removable busses.
  • Chain to full userspace.
  • Restart udevd, or at least instruct it to change its inotify watch on rules.

udev

  • Upgrade to udev-071 plus current git patches.

Git patches after 071 cause the rules to be cached. It's best to just accomodate this now. Current git patches also add more man pages, and some extra needed UUID support.

  • Implement scroreboard from HardwareActivation

  • Implement udevplug from HardwareActivation

  • Mark udev as Provides, Conflicts, Replaces for hotplug
  • Make sure hotplug is cleaned away in postinst, moving the init script to .dpkg-old, etc.
  • Move the existing isapnp maps from hotplug and put them in udev. Continue to update them as we discover more devices that need to go in.
  • Add udev rules to put USB Devices in /dev/bus/usb.

hotplug

  • Ask the ftpmasters to remove from the archive.

modutils

  • Upgrade modutils to recent version to get blacklisting support.

klibc

  • udev should be compiled against a recent version of klibc for tiny initramfs images

full userspace init scripts

  • As soon as full userspace has started, need to tell udev to reread all of the rulesets.
  • Where udevstart and coldplugging routines are currently started, 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.

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.

Outstanding issues

Rebooting the system shortly after the upgrade is critical. It is quite likely that hal will stop working, and the rules that are on the harddrive may then be completely incompatible. The cute little lightbulb "Please click on me for a message" in the corner is probably insufficiently invasive to make sure this happens. That notification applet should be refered to mpt for a case of the mean-and-ugly treatment. This is out of scope for this spec.

This spec has been created as https://launchpad.net/distros/ubuntu/+spec/urgent-reboot-notification

UdevRoadmap (last edited 2008-08-06 16:16:48 by localhost)