On Fri, May 02, 2003 at 11:34:23PM -0700, Gora Mohanty wrote:
> Is it really true that the speed difference is negligible?
Well, it's only really true for bulk transfers in a defined IEEE 1284
transfer mode like ECP, to be fair. For custom protocols it will be
much slower in user-space, but for IEEE 1284 modes: it depends. When
user-space write()s a large amount, the kernel is doing the transfer
protocol stuff anyway, so in that sense the difference should be
negligible for that situation.
Basically I imagine it depends how much of the logic is in user-space.
> Also, does anyone know if there is a limit to the number of parallel
> ports/PCI parallel port cards that can be supported by Linux on a x86 PC?
> A friend claims that only a max. of 4 can be supported, though he could
> not explain why. I also see that my PC has only /dev/parport0 through
There's a #define you can tweak in inlude/linux/parport.h (when
recompiling the parport modules). PARPORT_MAX is currently set at 16
in the kernel I'm using.
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