Re: UDEV from scratch for beginners - mtd device not shown in device

[Clemens Koller <clemens.koller@anagramm.de>]

Hello, Kai!

Thank you for filling the gaps. The problem was:

>>The error messge about failed exec of udev_run_devd doesn't appear anymore.
>>But I still cannot get my /dev/mtd/0 created...
> 
> 
> Mtd seems to lack proper driver-core integration, and therefore no udev
> support:
>   http://lists.infradead.org/pipermail/linux-mtd/2005-June/012821.html
> 

The latest 2.6.13-rc2 tree didn't use class_simple_device_xxx() to register
new devices. I've patched my tree with the patch in above link and I've also
applied no-sources-keep-class-symbol.diff for simple_class.c

Now everything seems to work fine, I get my mtd device added and removed
properly.

Thanks for your support!

Greets,

Clemens Koller
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Kay Sievers wrote:
> On Mon, Jul 11, 2005 at 03:19:32PM +0200, Clemens Koller wrote:
> 
>>After installing "udev from scratch" on an embedded system
>>(not being able to follow Decibels UDEV Primer directly as I don't use
>>any package management tools.) I still cannot get my mtd
>>(memory technology device) node created dynamically by udev when I
>>insert my module to the kernel.
>>
>>Basically, my installation was like this:
>>
>>- compiled Linux-2.6.13-rc2 w/ CONFIG_UNIX98_PTYS and CONFIG_DEVPTS_FS
>>and CONFIG_HOTPLUG and friends.
>>
>>- manually created /dev nodes on local filesystem to be able to boot
>>and login via ssh at least:
>>cd /dev
>>mknod -m 660 console c 5 1
>>mknod -m 666 null c 1 3
>>mknod -m 666 hda b 3 0
>>mknod -m 666 hda1 b 3 1
>>mknod -m 666 hda2 b 3 2
>>(I guess I will have to move those manually created devices to
>>/etc/udev/devices, right? Where is documentation for that and who
>>is copying that to /dev and when?)
> 
> 
> This is Fedora specific, udev does not do it by default.
> 
> 
>>(BTW: in which order are the files in /etc/udev/rules.d processed if
>>there are more than one?
> 
> 
> Lexical order.
> 
>>Are there any naming conventions which apply?
>>Where is the documentation for that?)
> 
> 
> The man page.
> 
> 
>>- I've checked /udev/uevent_listen which works pretty fine while
>>loading my mtd modules:
>>
>>$ ./uevent_listen
>>[1121084998] received 'remove' from '/module/mminfo'
>>ACTION=remove
>>DEVPATH=/module/mminfo
>>SUBSYSTEM=module
>>SEQNUM\x181
>>
>>[1121085000] received 'add' from '/module/mminfo'
>>ACTION­d
>>DEVPATH=/module/mminfo
>>SUBSYSTEM=module
>>SEQNUM\x182
>>
>>while doing
>>$ rmmod mminfo
>>$ insmod mminfo.ko
> 
> 
> These are module events and not events for class or block devices. udev
> will not create any node for such events.
> 
> 
>>Now I ran into the following problem while loading my module
>>which appeared as /dev/mtd/0 and/or /dev/mtd/0ro in devfs:
>>
>>Jul 11 13:33:29 ecam udevd[14647]: udevd.c: seq 177 forked, pid 14653, 2 
>>seconds old
>>Jul 11 13:33:29 ecam udev[14653]: udev_rules.c: reset run list
>>Jul 11 13:33:29 ecam udev[14654]: udev_utils.c: exec of program 
>>'/sbin/udev_run_devd' failed
>>Jul 11 13:33:29 ecam udevd[14647]: udevd.c: seq 177 exit, 2 seconds old
>>Jul 11 13:42:32 ecam udevd[14647]: udevd.c: seq 178 queued, devpath 
>>'/module/mminfo'
>>Jul 11 13:42:32 ecam udevd[14647]: udevd.c: seq 178 forked, pid 14662, 0 
>>seconds old
>>
>>I patched udev_utils.c (appended, whitespaces fixed, too) to get the clue
>>that the call to /sbin/udev_run_devd failed.
>>
>>Well, there is no valuable documentation about udev_run_devd neither in
>>writing_udev_rules nor in Decibels UDEV primer. So I decided to remove
>>that line from the 50-udev.rules:
>># emulate dev.d/
>>#RUN="/sbin/udev_run_devd"
>>without really knowing what that is...
>>(What is a directory multiplexer doing? Do I need that? For what?)
> 
> 
> Look at the archives, and RELEASE-NOTES. dev.d/ is a hotplug.d/ style
> directory, where you can place programs in, that run at device node
> creation/removal.
> 
> 
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