Re: PATCH: serial patch for PPC

Paul Mackerras (paulus@linuxcare.com)
Wed, 29 Sep 1999 16:11:04 +1000


On Wed, 29 Sep 1999, tytso@mit.edu wrote:

> That shouldn't be causing a problem, though, as long as PPC systems are
> either/or as far as Z8530 or 16550 UARTs are concerned.

They are, mostly, but not entirely. This becomes an issue if you have an
apple laptop with a pcmcia modem card that looks like a 16550 (as I do) or
if you want to build a kernel which will work both on machines with 8530s
and on machines with 16550s. And there are in fact a few machines with
both 8530s and 16550s. I have one, and at the moment I just don't use the
8530s.

> The tty_register_driver code currently doesn't mind if there is overlap
> in the minor number space, actually. The most recently loaded driver
> wins. The only time when register_tty_driver() will fail is if the
> major number has already been grabbed by a non-tty driver. That's why I

I don't know what non-tty driver would be grabbing that major.

Paul.

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