Udev changes

Duncan Webb duncan at linuxowl.com
Thu Oct 27 02:32:14 PDT 2005

Alexander E. Patrakov wrote:

> Duncan Webb wrote:
>> Matthew Burgess wrote:
>>> Forwarding from blfs-dev, where an ALSA related thread went just a 
>>> little off-topic for BLFS :)
>>> 2) Add these two rules to LFS default rules file:
>>> ENV{UDEVD_EVENT}=="1", RUN+="/sbin/udev_run_hotplugd"
>>> RUN+="/sbin/udev_run_devd"
>> Don't think that RUN+="/sbin/udev_run_devd" is requires for LFS as it 
>> doesn't use devfs any more.
> This is not for devfs! This is for compatibility with obsolete 
> packages that still install scriptlets into /etc/dev.d. I.e., after 
> /dev/lp0 is created, this rule executes the following scripts if they 
> exist:
>         /etc/dev.d/lp0/*.dev
>         /etc/dev.d/printer/*.dev
>         /etc/dev.d/default/*.dev
> This may be used in order to download firmware into certain printers 
> (/etc/dev.d/lp0/firmware.dev contains "#!/bin/sh cat firmware 
> >/dev/lp0" then). More modern approach is to use RUN+=... rules 
> instead of dev.d scriptlets. BTW BLFS 6.1 uses a dev.d scriptlet for 
> ALSA volume restoration (BLFS SVN converted this to the RUN rule).
> So you are right that LFS and BLFS SVN contain no such obsolete 
> packages that need /etc/dev.d.
>> I think that you can also add:
>> Add the rules to /etc/udev/rules.d/60-hotplug.rules
>> #
>> # usbfs-like device nodes
>> SUBSYSTEM="usb_device", PROGRAM="/bin/sh -c 'X=%k X=$${X#usbdev} 
>> B=$${X%%%%.*} D=$${X#*.}; echo bus/usb/$$B/$$D'", SYMLINK+="%c"
> Only after linux-2.6.14 please, and synchronously with patching libusb 
> in BLFS and removing the /proc/bus/usb mount. But those rules will of 
> course do no harm with earlier kernel.
>> # be backward compatible for a while with the /etc/dev.d and 
>> /etc/hotplug.d/ systems
>> # run /etc/hotplug.d/ stuff only if we came from a hotplug event, not 
>> for udevstart
>> ENV{UDEVD_EVENT}=="1", RUN+="/sbin/udev_run_hotplugd"
> Correct. But that alone doesn't run /etc/dev.d stuff, you need 
> RUN+="/sbin/udev_run_devd" for that.
>> I'm not 100% sure but I think that pciutils (plus 
>> pcimodules-pciutils-2.1.11.diff patch) and usbutils are also needed.
> They are needed with 2.4 kernels only (i.e.: not needed at all in LFS) 
> for hotplug to work correctly. All the needed information is gathered 
> from sysfs with 2.6 kernels.
>> To log hotplug events you could also add:
> What's wrong with the current way to log events into 
> /var/log/hotplug/events?

Nothing at all.

I was trying to figure out why nothing was being logged in 
/var/log/hotplug/events, so I enabled the hotplug debug option then 
there was quite a lot of output so I figured that it was better to keep 
the log separate.

Thanks for the info, it's cleared up a few uncertainties that I had.


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