Problem with built-in USB memory card reader

Micah micahjon at
Wed Jan 3 14:23:21 PST 2007

Alexander Pohoyda wrote:
> Lowell Gilbert writes:
>> Alexander Pohoyda <alexander.pohoyda at> writes:
>>> Everything works perfect if the system is started with a memory card
>>> inserted into the reader.
>>> The problem arises when the system is started without the memory card
>>> inserted.  Since the reader is built-in (permanently attached to the
>>> motherboard), it is detected by the system at startup and no umass
>>> device is created.  Inserting a memory card at some later time has no
>>> visible effect whatsoever.
>>> I'm using the 5.4 release.  Is there a solution for this?
>> USB handling would be better in a more recent release of FreeBSD, but
>> I think you should be getting the basic da(4) device, just not the
>> slices (which aren't there yet) if the medium isn't available at
>> boot.  Is that the case?  [I haven't done this in a while, and don't
>> have access to a card reader at the moment.]
> Yes, exactly.  If no memory cards were inserted at the boot, only
> da(4) devices are created and inserting/removing memory cards
> afterwards has no visible effect.  This behavior is well known also
> for external USB card readers, but those are easily
> detached/re-attached which triggers their re-scanning.
> I'm asking because Ms Windows somehow gets the insertion event and
> mounts the memory card automatically.  So that is be possible.
> Does anybody know how that is done?

There is a hack, but I can't quite remember it. I think it was "true > 
/dev/da0" to get devfs to reread the partitions and create the dev 
entires. I haven't been able to get to a reader to test it though. Test 
on a junk media card just in case I'm totally off base.

- Micah

More information about the freebsd-questions mailing list