Problem with 16-in-1 card reader

[M. Warner Losh]

In message: <20060311124931.62eee647 at frankie.konav201.local>
            Robert Marella <rmarella at gmail.com> writes:
: On Sat, 11 Mar 2006 13:51:30 +0100
: Alex Dupre <ale at FreeBSD.org> wrote:
: 
: > My new PC has an internal 16-in-1 card reader connected via USB 2.0.
: > The device is the Techsolo TCR-1640
: > (http://www.techsolo.de/product/cardreader/tcr_1640/index.php).
: > I boot from a compact flash inserted in it and I can mount and unmount
: > the same CF once the system has booted and has mounted the root
: > partition from my graid3 array.
: > The problem arise when I replace the inserted CF with another one
: > (with different size and filesystem) and try to mount it. Fdisk can
: > correctly sees the new partition table, but devfs is not updated and
: > I cannot mount the new media. 
: 
: <snip>
: 
: Hello Alex
: 
: This problem has been discussed many times on the lists. In order to
: update devfs you can use:
: 
: cat /dev/null > /dev/daX
: 
: I seem to remember another method using dd.

dd if=/dev/null of=/dev/daX count=0