Re: Is it useful to support user level drivers

[David S. Miller]

Mike Mackovitch writes:
 > On Thu, Jun 21, 2001 at 04:22:32PM -0700, David S. Miller wrote:
 > > What the heck is ULI then?  I've actually read the assembly code for
 > > this back when I did my SGI internship.
 > 
 > If my memory serves me correctly, I believe ULI was some
 > hacked up "user-level interrupt" feature.  I have no idea
 > who (if anyone) used it, but it definitely wasn't used by
 > SGI's graphics drivers.

Strange, because taking veritcal retrace interrupts directly in
userspace was the first thing that came to my mind when I saw
what ULI was doing.

When IRIX optimizes something to the extreme, it is either for
big-iron or graphics performance, very few exceptions exist :-)

Later,
David S. Miller
[e-mail]