GEOM weirdness with SD flash reader?

[M. Warner Losh]

In message: <46880400.70808 at root.org>
            Nate Lawson <nate at root.org> writes:
: Simply trying to mount a FAT filesystem in an external USB SD flash
: reader.  The reader works fine, no errors in dmesg.
: 
: deenlo# fdisk da2
: ******* Working on device /dev/da2 *******
: parameters extracted from in-core disklabel are:
: cylinders=982 heads=64 sectors/track=32 (2048 blks/cyl)
: 
: parameters to be used for BIOS calculations are:
: cylinders=982 heads=64 sectors/track=32 (2048 blks/cyl)
: 
: Media sector size is 512
: Warning: BIOS sector numbering starts with sector 1
: Information from DOS bootblock is:
: The data for partition 1 is:
: sysid 6 (0x06),(Primary 'big' DOS (>= 32MB))
:     start 243, size 2011917 (982 Meg), flag 0
:         beg: cyl 0/ head 3/ sector 55;
:         end: cyl 998/ head 3/ sector 3
: The data for partition 2 is:
: <UNUSED>
: The data for partition 3 is:
: <UNUSED>
: The data for partition 4 is:
: <UNUSED>
: deenlo# mount -t msdosfs /dev/da2s1 /mnt/dos
: mount_msdosfs: /dev/da2s1: No such file or directory
: deenlo# mount -t msdosfs /dev/da2 /mnt/dos
: mount_msdosfs: /dev/da2: Invalid argument
: deenlo# mount -t msdosfs /dev/da2s1 /mnt/dos
: [success]
: 
: So I'm guessing GEOM had to decide to create /dev/da2s1 after I tried to
: mount /dev/da2 directly?  Nothing else would create the da2s1 device.
: Once the device was created with make_dev(), repeated unmounts/mounts
: work fine.

The reading of the device is taking a while, no?  I've seen
significant lags between when the flash reader is inserted, and the
device is ready and the tasting process finishes.  Reseating
everything often fixes the problem.

Warner