virmidi, hotplug and udev

virmidi, hotplug and udev

[Carlos Pita]

Hi!

I'm using kernel 2.6.8 with hotplug enabled and udev
(distro: debian sarge).

I need to use the snd-virmidi to create a virtual sound card
with its raw midi devices.

I do:
  modprobe snd-virmidi

Does this generate a hotplug event? Or at least an udev event?

I ask it because here the order is somewhat inverted. Normally
a device is cold/hot plugged and modprobe is run in
response to a subsequent hotplug event. But here the device is
added as the effect of a previous modprobe. One thing I see
is that modprobe would be retried as part of the event processing,
that's innocuous but ugly.

Finally, do you know how to write the udev rules to generate
the OSS raw midi devices. Currently, the only rules related
to ALSA in my /etc/udev/rules.d/udev.rules are:

# ALSA devices
KERNEL="controlC[0-9]*", NAME="snd/%k"
KERNEL="hw[CD0-9]*",    NAME="snd/%k"
KERNEL="pcm[CD0-9cp]*", NAME="snd/%k"
KERNEL="midi[CD0-9]*",  NAME="snd/%k"
KERNEL="timer",         NAME="snd/%k"
KERNEL="seq",           NAME="snd/%k"

Most of the OSS devices are generated at boot time by
udevstart. But /dev/midi10.../dev/midi13 are missing after
modprobing snd-virmidi.

Thank you in advance.
Regards,
Carlos


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Re: virmidi, hotplug and udev

[Takashi Iwai]

At Sun, 28 Nov 2004 18:51:29 -0300,
Carlos Pita wrote:
> 
> Hi!
> 
> I'm using kernel 2.6.8 with hotplug enabled and udev
> (distro: debian sarge).
> 
> I need to use the snd-virmidi to create a virtual sound card
> with its raw midi devices.
> 
> I do:
>   modprobe snd-virmidi
> 
> Does this generate a hotplug event? Or at least an udev event?
> 
> I ask it because here the order is somewhat inverted. Normally
> a device is cold/hot plugged and modprobe is run in
> response to a subsequent hotplug event. But here the device is
> added as the effect of a previous modprobe. One thing I see
> is that modprobe would be retried as part of the event processing,
> that's innocuous but ugly.
> 
> Finally, do you know how to write the udev rules to generate
> the OSS raw midi devices. Currently, the only rules related
> to ALSA in my /etc/udev/rules.d/udev.rules are:
> 
> # ALSA devices
> KERNEL="controlC[0-9]*", NAME="snd/%k"
> KERNEL="hw[CD0-9]*",    NAME="snd/%k"
> KERNEL="pcm[CD0-9cp]*", NAME="snd/%k"
> KERNEL="midi[CD0-9]*",  NAME="snd/%k"
> KERNEL="timer",         NAME="snd/%k"
> KERNEL="seq",           NAME="snd/%k"
> 
> Most of the OSS devices are generated at boot time by
> udevstart. But /dev/midi10.../dev/midi13 are missing after
> modprobing snd-virmidi.

There are no /dev/midi1x devices on OSS.
As written in my last post, the OSS device has no concept of "card".
It just accepts the device in a serial order.

Nevertheless, OSS supports only up to 4 devices for /dev/midi0?.
(You can use more 4 devices with /dev/amidi?, too, though.)


Takashi


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