Device probe issue with an em(4) compatible device

M. Warner Losh imp at
Wed Sep 29 17:04:07 PDT 2004

In message: <1096485467.2670.1127.camel at localhost.localdomain>
            Brenden Grace <bcg at> writes:
: On Wed, 2004-09-29 at 13:37, Peter Buckingham wrote:
: > why compile the em driver in at all? it won't probe the device if it 
: > doesn't exist ;-)
: because I need it ...

As opposed to just hacking the em driver?

: > otherwise, just add some code to the em's probe routine to check for 
: > your subvendor, subdevice pair and exit without attaching.
: Well sure (though ugly), but I think having it just return a negative
: number would be a better fix than that. I was more interested in why the
: em driver (and others) returns 0 and ends the probing of a device that
: it could possibly only partially support (based on its matching of
: PCI_ANY_ID). If I understand DEVICE_PROBE(9) correctly it seems that the
: whole reason for the negative return scale is to avoid this very issue.

That's correct.  PCI_ANY_ID has nothing to do with it.  If em_probe
returns 0, it trumps all other drivers for that device that haven't
had a chance to bid (as well as the potential drivers that bid a
negative number).


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