Re: udev notes

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Alan J. Wylie wrote:
> 1) udevstart is no longer in udev 084
> 
>     <http://lwn.net/Articles/154268/>
>     <http://article.gmane.org/gmane.linux.hotplug.devel/9251>
> 
>    the recommended way of setting up the device nodes from kernel
>    2.6.15 on is now something like:
> 
>     --------------------------------------------------------------------------
>     for i in /sys/block/*/uevent; do echo 1 > $i; done
>     for i in /sys/block/*/*/uevent; do echo 1 > $i; done
>     for i in /sys/class/*/*/uevent; do echo 1 > $i; done
>     for i in /sys/class/*/*/*/uevent; do echo 1 > $i; done
>     for i in /sys/bus/*/devices/*/uevent; do echo 1 > $i; done
> 
>     # wait until udevd has finished before using devices, e.g. swap
>     loop=0
>     while test -d /dev/.udev/queue; do
> 	    sleep 0.1;
> 	    if test "$loop" -gt 300
> 	    then
> 		echo "udev queue timed out"
> 		status=1
> 		break
> 	    fi
> 
> 	    loop=$(($loop + 1))
>     done
>     --------------------------------------------------------------------------

What about creating a script called 'udevstart' that does exactly this? I would
need this because currently udev doesn't set users and group permissions from
within the initrd, no idea why. /etc/{passwd,group} are there.

> 2) If /etc/initscript is going to do all the setup, we no longer need
>    to mount /proc, /sys, /dev/shm and /dev/pts in /etc/init.d/system,
>    or for /etc/init.d/udev to exist

Should be done from the initrd.

> 3) It seems that you need to have a console char device in the /dev
>    directory on the root file system, otherwise the kernel gives an
>    error message "Warning: unable to open an initial console".
>    See linux/init/main.c before it tries to exec init.
>    Without this, adding "init=/bin/sh" to the grub line won't work.

Without it, _nothing_ will ever boot, because the moment the kernel gives
control to a userspace program it will die with:
PANIC: Can't open initial console.

> 4) "kill -USR1 1" in /etc/initscript after /dev is mounted will cause
>    init to close and reopen its control fifo /dev/initctl which will
>    otherwise be hidden.

Good, let's do that.

> 5) With udev, /dev/misc/microcode is instead at /dev/cpu/microcode.
> 
>    The patch file package/x86/microcode_ctl/devfs.patch is not
>    applicable to udev based systems.
> 
>    Create a compatibility symlink in a udev rule perhaps?

Do other programs but microcode_ctl depend on /dev/misc/microcode? Otherwise
change that package to use /dev/cpu/microcode and be done with it.



Greetings,
	Benjamin

- --
Today, memory either forgets things when you don't want it to,
or remembers things long after they're better forgotten.
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