[mythtv-users] OT? /proc/pci

[Joel Anderson]

Marc-David Meijer wrote:
> 
>>-----Oorspronkelijk bericht-----
>>Van: mythtv-users-bounces at mythtv.org [mailto:mythtv-users-
>>bounces at mythtv.org] Namens Sean Covel
>>Verzonden: maandag 12 juli 2004 16:12
>>Aan: Discussion about mythtv
>>Onderwerp: Re: [mythtv-users] OT? /proc/pci
>>
>>Stephen Tait wrote:
>>
>>>At 08:13 12/07/2004 -0400, you wrote:
>>>
>>>
>>>>Stephen,
>>>>
>>>>Thanks for your response.  That's what I suspected, but I wanted to be
>>>>sure before I got drastic.
>>>>
>>>>The box that the PVRs are in is a bit overloaded, IRQ-wise.  I had to
>>>>add an IDE controller, video, sound, and LAN, just to get started.
>>>>Despite disabling the on-board IDE (udma33), I suspect its taking up
>>>>IRQs.  I was already thinking about moving MythTv to another, more
>>>>modern box.  Guess I'll just have to do it!
>>>>
>>>>Sean
>>>
>>>
>>>You have to watch those PCI-IDE controllers, if they're anything like
>>>the Promise TX2 I've got, they take up a whole IRQ as well. More modern
>>>boxes don't necessarily help either... just try disabling all the gumpf
>>>in the BIOS (onboard sound, parallel, serial, yadda yadda) before you
>>>splurge on new HW.
>>>
>>>Depending on the BIOS you've got, it should give you a less-than-helpful
>>>rundown of what  hardwares are using which IRQ's (my crummy old mATX P3
>>>board that I'm trying to bludgeon back to life tends to lump everything
>>>that isn't USB or NIC as a "multimedia controller"). Hope this is of
>>>some use; someone more knowledgeable might have a better idea of what's
>>>going on.
> 
> 
> On the other hand, I have three devices on irq 10 (onboard sound, nic and
> tv-card), and they all work, so it doesn't have to be the problem.
> 
> Best regards,
> Marc-David
> 

As I understand it, PCI devices don't depend on IRQs anyway.  They use 
interrupt "channels", and IRQs are just kept around to keep legacy stuff 
happy.  You will often see many devices appear to "share" the same IRQ, 
but it is not really true since IRQ's can't really _be_ shared.

Someone please comment if I haven't explained this correctly.  It's a 
simplification, but it basically means that IRQ issues shouldn't come 
into play unless you have some legacy hardware in the system also.

Joel