Hitchhiker's Guide to Openbsd

12.1 - General hardware notes
12.1.1 - PCI devices
●
PCI devices are mostly self-configuring -- the computer and OS will allocate resources to the 
cards as required. 
●
Interrupts can be shared on the PCI bus. Not only can they be, the system will often perform 
better when the IRQs are shared, especially on i386 systems. 
●
There are several different PCI bus standards. You will occasionally find a PCI2.2 specification 
card that will just not work in a PCI2.1 specification system. Also, many cards with on-board 
bridges (such as, multi-port network cards) will not work well in older systems. 
●
The PCI bus supports two levels of signaling, 3.3V and 5V. Cards that work with 3.3V signaling 
have a second notch cut in their PCI connector. Most PCI cards use 5V signaling, which is used 
by most computers. The Soekris single-board computers (Net45x1 and Net4801) are commonly-
encountered computers that only support 3.3V signaling. 
12.1.2 - ISA devices
●
ISA devices cannot share resources, and in general, must be manually configured to settings that 
don't conflict with other devices in the system. 
●
Some ISA devices are "Plug and Play" (
isapnp(4)
) -- if you have any problem with these devices, 
though, verify their configuration in your 
dmesg(8)
, ISAPnP doesn't always work as desired. 
●
In general, if you have a choice, most people are best advised to avoid ISA cards in favor of PCI. 
ISA cards are more difficult to configure and have a much greater negative impact on the 
http://www.openbsd.org/faq/faq12.html (2 of 12)9/4/2011 10:02:18 AM

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12 - Hardware and Platform-Specific Questions
system's performance. 
12.1.3 - My device is "recognized" but says "
not configured
" in dmesg
In short, it means your device is not supported by the kernel you are using, so you will not be able to use 
it. 
PCI and many other types of devices offer identifying information so that the OS can properly recognize 
and support devices. Adding recognition is easy, adding support is often not. Here is part of a dmesg 
with two examples of "not configured" devices: 
...
vendor "Intel", unknown product 0x5201 (class network 
subclass ethernet,
rev 0x03) at pci2 dev 9 function 1 not configured
...
"Intel EE Pro 100" rev 0x03 at pci2 dev 10 function 0 not 
configured
...
The first one (a network adapter) had its vendor code identified and the general type of card was 
determined, but not the precise model of the card. The second example was another network adapter, 
this one a developer had seen and had entered into the identification file that is used to identify the card. 
In both cases, however, the cards will be non-functional, as both are shown as "
not configured
", 
meaning no driver has attached to the card.