This is the mail archive of the
ecos-discuss@sources.redhat.com
mailing list for the eCos project.
RE: PCI Ethernet card (DHCP issue)
- From: "Andy Dyer" <adyer at righthandtech dot com>
- To: <ecos-discuss at sources dot redhat dot com>
- Date: Wed, 17 Sep 2003 22:54:48 -0500
- Subject: RE: [ECOS] PCI Ethernet card (DHCP issue)
> From: ecos-discuss-owner@sources.redhat.com on behalf of Eric Doenges
> Sent: Wed 9/17/2003 8:26 AM
> To: Michael Anburaj
> Cc: ecos-discuss@sources.redhat.com
> Subject: Re: [ECOS] PCI Ethernet card (DHCP issue)
> Michael Anburaj wrote:
>
>
> > 2. The PCI interrupts seems to be mapped in the following manner <My
> > assumption>:
> >
> > PCI device number Interrupt controller PIN
> > 0,4,8... INTC
> > 1,5,9... INTD
> > 2,6,10... INTA
> > 3,7,11... INTB
> >
> > Is this right? Let me know how to know this & is there any material
> > regarding this?
>
> AFAIK, the PCI specs do not make any assumptions on how PCI interrupts
> are mapped to 'real' interrupts; this is left to the vendor's
> discretion (and should be documented by the vendor).
How the PCI interrupts are mapped depends on how the physical slots
are hooked up - both how the IDSEL pins are connected and how the
INT[A-D] signals go.
Since almost all cards only support the INTA signal, IIRC it is
recommended (not required) in the PCI spec that the interrupts be
done like this:
slot # slot signal motherboard
signal
1 INTA INTA
1 INTB INTB
1 INTC INTC
1 INTD INTD
2 INTA INTB
2 INTB INTC
2 INTC INTD
2 INTD INTA
3 INTA INTC
3 INTB INTD
3 INTC INTA
3 INTD INTB
4 INTA INTD
4 INTB INTA
4 INTC INTB
4 INTD INTC
and this repeats for more slots or other on-board
devices using that same PCI bus segment. This makes
for the minimum amount of interrupt sharing by
spreading the add-in card INTA signals across all
the PCI INT signals.
--
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss