Thanks to David S for this
link.
“Must [hardware] vendors release source code with any Linux
add-on?”
“Hardware compatability isn’t as automatic under Linux as it is
under Windows. In particular, you have to make sure the SCSI
controller you want to use is supported under Linux. That is less
of a problem today than it was a year ago, but it still requires
some extra care.”
“The difficulty comes in the interaction between the GNU Open
Source license and the controller vendors’ desire to keep trade
secrets.”