[Debian-eeepc-devel] Using a pre-populated /dev for faster boot

[Santi Béjar]

On Sat, Nov 1, 2008 at 1:12 PM, Phil Endecott
<phil_dlhbb_endecott at chezphil.org> wrote:
> Santi B?jar wrote:
>>> I do this by adding the option "--subsystem-match=usb" to the
>>> udevadm trigger call.  It's only the coldplugging for built-in devices
>>> that I've removed.
>>
>> Then udev only has info about the usb devices, in particular the
>> synaptics touchpad is not included, so hal does not list it, so
>> xserver 1.5 which takes input devices from hal does not configure the
>> synaptics. xserver 1.5 is only in experimental so it is not a problem
>> for now.
>
> Ah, "HAL".  I've seen that mentioned a few times and wondered what it
> is; I don't have it installed.  What does it do?

It abstract the hardware so programs does not need to know the details.

In the EeePC I used it for the NetworkManager and XFCE (it is only
recommended) to mount devices (and gnome-mount), and now for the
Xserver. (I'm not the only user of the eee).

>
> Can't xserver 1.5 be configured to work in a more traditional way?  Or
> can't HAL be configured to know about devices independent of what udev
> has done?

Yes, but I want the autodiscovery/autoconfigure.

>
>>> In order to pre-populate /dev with entries for the coldplugged devices,
>>> I have hacked /etc/init.d/udev to check for and untar a file called
>>> /etc/init-devs.tar.  If it doesn't find it, it falls back to the old
>>> behaviour.  If it does exist, after untarring it does coldplugging for
>>> only usb devices as described above.
>>
>> I've done it differently. I've copied the devices from /dev to
>> /lib/udev/devices, and they get copied to /dev at boot (without
>> modifying /etc/init.d/udev).
>
> I decided to keep it separate so that it can be disabled more easily.

To disable just "mv /lib/udev/devices /lib/udev/devices_disabled".

> And I would like to think that un-tarring is quicker than recursive
> copying - fewer system calls.

Maybe, but the main issue here is the trigger of coldplugging devices,
not the creation of the /dev files.

Santi