Re: no ioctls for serial ports? [was Re: LANANA: To Pending DeviceNum

Alexander Viro
2001-05-20T15:18:52Z

On Sun, 20 May 2001, Abramo Bagnara wrote:

> > Face it, we _already_ have more than one side band.
>
> This does not imply it's necessarily a good idea.
> We are comparing
>
> echo "9600" > /proc/self/fd/0/speed (or /dev/ttyS0/speed)
> echo "8" > /proc/self/fd/0/bits (or /dev/ttyS0/bits)
>
> with
>
> echo -e "speed 9600\nbits 8" > /proc/self/fd/0/ioctl (or
> /dev/ttyS0/ioctl).

How about reading from them? You are forcing restriction that may make
sense in some cases, but doesn't look good for everything.

> > Moreover, we have channels that are not tied to a particular device -
> > they are for a group of them. Example: setting timings for IDE controller.
> > Sure, we can just say "open /dev/hda instead of /dev/hda5", but then we
> > are back to the "find related file" problem you tried to avoid.
>
> It does not seems appropriate to permit to change IDE timings using an
> handle to a partition... nor it seems very safe under a permissions
> point of view.

However, we _do_ allow that. Right now. And yes, I agree that we should
go to separate file for that. And we are right back to finding a related
file.

It's not a function of descriptor. Sorry. Just as with /dev/tty1 -> /dev/vcs1
and its ilk.