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volumetricsteve

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Registered: 2014-09-08

Posts: 50

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[SOLVED]devices only seem to work in certian pci slots

I'm trying to optimize airflow in a certain enclosure so I moved some pci cards (not pci express, old-school 32-bit pci) into different slots

On first reboot, everything flipped out and only the nic of the 3 cards worked (an intel nic, a 5-port usb card, and a sound blaster live)  both the sound card and the usb card threw tons of errors that showed up moments before, and spilling over into the login prompt.

Vaguely recalling something I had heard about soundcards suggested that they need to be handled specially, so I took out the other two cards, and rebooted again with only the SB live in it's new slot - this fixed the sound card relocation.

After that I tried to put the usb card and nic back in, but the usb card errors continued to show up...things like "over-current detected" plus some other more cryptic messages I don't recall - however, when I swapped it back to it's original slot, this all goes away.

The nic seems happy no matter where it's at.

Right now, the system is working, but I can't seem to get it to work if I put the usb card and nic in the slots I want them to go in.  It's not a show stopper but it's curious and I'm wondering if this behavior is an Arch thing, a Linux thing, a motherboard thing, or maybe even a card thing.  Any ideas?

Last edited by volumetricsteve (2015-06-09 13:56:40)

Lone_Wolf

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From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,167

Re: [SOLVED]devices only seem to work in certian pci slots

I do remember vaguely some motherboards where some pci slots shared interrupts, or where not all slots supported the same pci version.
With multiple cards often things only worked in a specific combination.

The user manual of the motherboard should have details about this, what brand & model is this Mobo ?

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

volumetricsteve

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Registered: 2014-09-08

Posts: 50

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Re: [SOLVED]devices only seem to work in certian pci slots

Thanks for your reply!

It's an ancient Intel D820LP...nearly 15 years old, but it'll make a decent enough arcade machine.

I'll check again in the manual because I wondered that same thing...

I realized what I could to to test is take out the other cards, put the usb card in the slots that makes it freak out and boot off the arch install media, see if it throws the same kernel spasms...I just ran out of time yesterday

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,167

Re: [SOLVED]devices only seem to work in certian pci slots

On https://downloadcenter.intel.com/download/17797  you can download technical data about that mobo.

Extraxt the zip somewhere, and open pdf/A1575101.pdf , it has technical specs.

chapter 2.7 & table 16 show details about the way PCI interrupts are routed and can help to determine where to put which card.

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

clean chroot building not flexible enough ?
Try clean chroot manager by graysky

volumetricsteve

Member

Registered: 2014-09-08

Posts: 50

Website

Re: [SOLVED]devices only seem to work in certian pci slots

Thanks for the link....that contained way more info than I was able to find previously....

and you were correct, it appears PCI slot 3 shares an IRQ with slot 5 in such a way that 5 does not ask for an IRQ but is just given whatever 3 has.

I suppose this must mean that the usb card cares a lot more about being able to ask for an IRQ than the SB Live does....odd