Notes |
(0004854)
vapier
02-14-08 17:47
|
please post the hotplug environment and the sysfs path for the device that you are seeing problems with |
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(0004864)
espakman
02-15-08 02:45
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I see the same behaviour with the watchdog device and softdog module
mdev used for hotplugging, echo /sbin/mdev > /proc/sys/kernel/hotplug
/sys/devices/virtual/misc/watchdog
insmod softdog:
/dev/watchdog is added because of hotplugging by mdev, as block device:
brw-rw---- 1 root root 10,130
rm /dev/watchdog, mdev -s:
/dev/watchdog is added as character device:
crw-rw---- 1 root root 10,130
Obviously /usr/sbin/watchdog fails to start in the hotplugging case. |
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(0004874)
joeyoravec
02-15-08 06:49
|
Here's are two of my problem devices, info captured with "env >> /tmp/mdevlogfile" on a hotplug event. These are devices for an ALSA sound chip/card over a SPI bitbang bus. There's a dev file under dev path, and in this situation mdev should create a character device. Without my proposed patch it would create a block device.
As I said in the original posting "mdev -s" would work fine because it uses a completely different algorithm (scanning class and bus) and would correctly create a character device. On hotplug events the situation is different; the documentation says to use the SUBSYSTEM variable, not to parse the path.
ACTION=add
HOME=/
SEQNUM=115
MAJOR=116
DEVPATH=/devices/platform/ermine_spi_bb_dac26/spi3.0/sound/card0/pcmC0D0p
SUBSYSTEM=sound
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MINOR=16
PWD=/
ACTION=add
HOME=/
SEQNUM=116
MAJOR=116
DEVPATH=/devices/platform/ermine_spi_bb_dac26/spi3.0/sound/card0/controlC0
SUBSYSTEM=sound
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MINOR=0
PWD=/ |
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(0004944)
vapier
02-15-08 20:13
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i cannot reproduce this ... if this were actually a problem for me, i would have fixed it long ago
on my systems, mdev creates all of the alsa devices correctly (which are loaded as modules, not built into the kernel) and has been since 2.6.19 (i'm currently testing 2.6.24).
for example, with busybox-1.9.1:
root:/> ls -l /dev/watchdog
ls: /dev/watchdog: No such file or directory
root:/> modprobe softdog
Software Watchdog Timer: 0.07 initialized. soft_noboot=0 soft_margin=60 sec (nowayout= 0)
root:/> ls -l /dev/watchdog
crw-rw---- 1 root root 10, 130 Jan 1 18:30 /dev/watchdog
it looks like your DEVPATH is wrong ... it should always start with /class/... or /block/... that is why the algorithm works
for example, the environment from first execution with the softdog loading is:
SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
HOME=/
SEQNUM=97
MINOR=130
MAJOR=10
SUBSYSTEM=misc
DEVPATH=/class/misc/watchdog
ACTION=remove |
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(0005054)
joeyoravec
02-18-08 07:19
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Loading softdog for the first time, but you pasted an environment with ACTION=remove? That seems fishy.
I haven't seen any document that promises the kernel will only give devpaths with those two folders. Further, sysfs-rules.txt says that recent kernels have symlinks under /class/ and /block/ that point to a unified tree under /devices/. Finally there were a few discussions on lkml including http://lkml.org/lkml/2007/7/17/527 [^] with info that may not yet appear in the documentation.
I'm just doing the right thing by filing a bug report to let you know. Patching mdev to follow my interpretation of the documentation solved my problem, and I don't plan to argue this any further. I suggest that you post on LKML if you have any questions. |
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(0005064)
vapier
02-18-08 07:57
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it's the same, only the action differs
SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
HOME=/
SEQNUM=80
MINOR=130
MAJOR=10
SUBSYSTEM=misc
DEVPATH=/class/misc/watchdog
ACTION=add |
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(0006204)
mmarretta
03-29-08 03:55
|
I have the same problem.
When i plug a usb touchscreen, mdev creates a block device instead of character device.
This happens because hotplug calls mdev with the following variables:
ACTION: add
DEVPATH: /devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0/usb/tkpanel0
FIRMAWARE:
SUBSYSTEM: usb
In /sys/class/usb there is tkpanel0 but it's a link to /devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0/usb/tkpanel0.
So hotplug uses the real path ( /devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0/usb/tkpanel0 ) and doesn't use the link.
This occures with kernel version 2.6.22.
According to the document http://kernel.org/doc/pending/hotplug.txt [^] I'd suggest to use the variable SUBSYSTEM.
I have uploaded the patch witch I use. |
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(0006214)
vda
03-29-08 09:08
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Fixed in rev. 21557. Thanks |
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busybox-1.7.2-mdevblock.patch [^] (1,957 bytes) 02-14-08 16:14
