On Tue, May 27, 2003 at 12:29:09PM +0200, Peter Asemann wrote:
> 1. If "disallow method ppdev" is set - will there be any difference
> regarding functionality, superuser rights requirements, speed?
I think there are still some protocols that are not implemented inside
libieee1284 but are implemented in ppdev: so those protocols won't be
available when 'disallow method ppdev' is set. (I might be wrong;
they might all be implemented now.)
One feature of the ppdev method is that you only need to have
read/write access to /dev/parport0 to communicate on that port. One
other access method which has this nice non-root feature is /dev/port,
which libieee1284 will try. So if you are not root, and don't want to
use ppdev, better make sure you have access to /dev/port. (Of course,
that gives access to all I/O ports on the machine.)
But /dev/port is quite a lot slower than the ioperm method (needs
root).
Regarding speed: it depends what method will be used in its place, and
what type of protocol you are using. If you were using hardware
accelerated ECP, then yes it will be quite a lot slower to avoid
ppdev.
> 2. If libieee detects a "software (epp, ecp...) mode, which "software" is
> meant then? Is that software some driver libieee makes use of (ppdev?), or
> does libieee itself implement some protocols?
libieee1284 itself implements some protocols, and so does ppdev. When
CAP1284_{ECP,EPP}SWE is set it means that libieee1284 has a full
implementation of that mode, or knows that the method it will use
does. (For EPP at the moment libieee1284 itself only does data
transfers and not addresses.)
There isn't a way for the library to ask ppdev what modes it
implements in software, so it doesn't say anything about it.
Tim.
*/
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