[linux-dvb] Re: More than 4 DVB cards - again

["Irek Defee" <irek.defee@ondems.com>]

I can only confirm that in version 2.4 there is no problem whatsoever,
I am running machines with 6 cards installed since I have that many PCI
slots available and all is fine and stable. Another issue though is how 
much stream juice one can squeeze out of the cards at the same time...

Irek

-----Original Message-----
From: linux-dvb-bounce@linuxtv.org [mailto:linux-dvb-bounce@linuxtv.org]
On Behalf Of Michael Hunold
Sent: 22. kesäkuuta 2004 13:01
To: Peter Maersk-Moller
Cc: Johannes Stezenbach; linux-dvb@linuxtv.org
Subject: [linux-dvb] Re: More than 4 DVB cards - again

Hello,

On 06/22/04 10:27, Peter Maersk-Moller wrote:
> Seriously, using "extended minor number". How do I do that ?
> Are you talking about changing something in a config file
> or are you talking about rewriting the device driver ?

This must be changed in the dvb-core device handling.

> What is the limitation regarding more DVB devices than 4 ?

There can be 9 different types of devices per adapter 
(video,audio,sec,frontend,demux,dvr,ca, net) and each device can be 
present up to 4 times (ie. demux0, demux1, demux2, demux3)

Because everything needs to be a power of two, one adapter consumes 
16*4=64 minor numbers. Because of the fact you only have 256 minor 
numbers you're stuck with 4 adapters.

For 2.4 alone, the devfs implementation wasn't tied to major/minor 
numbers, so if you used devfs alone it was possible to support more that

4 adapters.

In 2.6 this has changed -- devfs is now more tightly coupled and is 
limited to major/minor numbers again.

But: major/minor numbers have been extended from 8 to 16 bit types, so 
it should be possible to support more devices, but this also affects the

surrounding system (ie. glibc must support this)

Additionally, udev/sysfs should be support which also overcomes this 
limitation.

But AFAIK nobody has worked on these problems so far, so ideas and 
patches are welcome.

> Kind regards
> --PMM

CU
Michael.