[linux-dvb] Re: MORE THAN 4 DVB DEVICES

[Holger Waechtler <holger@convergence.de>]

Daniel Sáez Domingo wrote:
> But I don't use devfs. I have created the /dev/dvb directory with
> makedev.napi and this is the result:
>
> [ DVB]# ll /dev/dvb/
> total 24
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter0
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter1
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter2
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter3
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter4
> drwxr-xr-x    2 root     root         4096 may 20 10:57 adapter5
>
> [ DVB]# ll /dev/dvb/adapter0
> total 0
> crw-rw----    1 root     video    250,   1 may 20 10:57 audio0
> crw-rw----    1 root     video    250,   6 may 20 10:57 ca0
> crw-rw----    1 root     video    250,   4 may 20 10:57 demux0
> crw-rw----    1 root     video    250,   5 may 20 10:57 dvr0
> crw-rw----    1 root     video    250,   3 may 20 10:57 frontend0
> crw-rw----    1 root     video    250,   7 may 20 10:57 net0
> crw-rw----    1 root     video    250,   8 may 20 10:57 osd0
> crw-rw----    1 root     video    250,   0 may 20 10:57 video0
>
> [ DVB]# ll /dev/dvb/adapter1
> total 0
> crw-rw----    1 root     video    250,  65 may 20 10:57 audio0
> crw-rw----    1 root     video    250,  70 may 20 10:57 ca0
> crw-rw----    1 root     video    250,  68 may 20 10:57 demux0
> crw-rw----    1 root     video    250,  69 may 20 10:57 dvr0
> crw-rw----    1 root     video    250,  67 may 20 10:57 frontend0
> crw-rw----    1 root     video    250,  71 may 20 10:57 net0
> crw-rw----    1 root     video    250,  72 may 20 10:57 osd0
> crw-rw----    1 root     video    250,  64 may 20 10:57 video0
>
> [ DVB]# ll /dev/dvb/adapter2
> total 0
> crw-rw----    1 root     video    250, 129 may 20 10:57 audio0
> crw-rw----    1 root     video    250, 134 may 20 10:57 ca0
> crw-rw----    1 root     video    250, 132 may 20 10:57 demux0
> crw-rw----    1 root     video    250, 133 may 20 10:57 dvr0
> crw-rw----    1 root     video    250, 131 may 20 10:57 frontend0
> crw-rw----    1 root     video    250, 135 may 20 10:57 net0
> crw-rw----    1 root     video    250, 136 may 20 10:57 osd0
> crw-rw----    1 root     video    250, 128 may 20 10:57 video0
>
> [ DVB]# ll /dev/dvb/adapter3
> total 0
> crw-rw----    1 root     video    250, 193 may 20 10:57 audio0
> crw-rw----    1 root     video    250, 198 may 20 10:57 ca0
> crw-rw----    1 root     video    250, 196 may 20 10:57 demux0
> crw-rw----    1 root     video    250, 197 may 20 10:57 dvr0
> crw-rw----    1 root     video    250, 195 may 20 10:57 frontend0
> crw-rw----    1 root     video    250, 199 may 20 10:57 net0
> crw-rw----    1 root     video    250, 200 may 20 10:57 osd0
> crw-rw----    1 root     video    250, 192 may 20 10:57 video0
>
> [ DVB]# ll /dev/dvb/adapter4
> total 0
> crw-rw----    1 root     video    251,   1 may 20 10:57 audio0
> crw-rw----    1 root     video    251,   6 may 20 10:57 ca0
> crw-rw----    1 root     video    251,   4 may 20 10:57 demux0
> crw-rw----    1 root     video    251,   5 may 20 10:57 dvr0
> crw-rw----    1 root     video    251,   3 may 20 10:57 frontend0
> crw-rw----    1 root     video    251,   7 may 20 10:57 net0
> crw-rw----    1 root     video    251,   8 may 20 10:57 osd0
> crw-rw----    1 root     video    251,   0 may 20 10:57 video0
>
> [ DVB]# ll /dev/dvb/adapter5
> total 0
> crw-rw----    1 root     video    251,  65 may 20 10:57 audio0
> crw-rw----    1 root     video    251,  70 may 20 10:57 ca0
> crw-rw----    1 root     video    251,  68 may 20 10:57 demux0
> crw-rw----    1 root     video    251,  69 may 20 10:57 dvr0
> crw-rw----    1 root     video    251,  67 may 20 10:57 frontend0
> crw-rw----    1 root     video    251,  71 may 20 10:57 net0
> crw-rw----    1 root     video    251,  72 may 20 10:57 osd0
> crw-rw----    1 root     video    251,  64 may 20 10:57 video0
>
> But when I try to access some file in adapter4 or adapter5, the error No
> such device appears.
>
> How can I solve this problem without devfs
It's not possible without problems. See dvbdev.c, line 68, macro 
nums2minor(). The adapter number is encoded using 2 bits, this means 
that you can adress only 4 DVB cards.

You could hack this macro to encode the adapter number with more bits, 
but it's a pretty ugly hack.

Better enable devfs in your kernel, install the devfsd deamon to provide 
all compatiblity devices, start it as one of the first init scripts, and 
then mount devfs at boottime or in your fstab over the /dev directory.

Holger



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