Messages in this thread | | | Date | Wed, 29 Sep 1999 07:17:23 +1000 | From | Paul Mackerras <> | Subject | Re: PATCH: serial patch for PPC |
| |
Ted T'so wrote:
> This patch doesn't look right to me. Even if there are no serial > ports, tty_register_driver() shouldn't be returning an error. If it's > returning an error, it means that something non-tty driver is grabbing > the tty major number. Simply papering over the error isn't the right > thing to do; the big question is why tty_register_driver is failing, > which translates into the question of who is grabbing TTY_MAJOR or > TTY_AUX_MAJOR on the "common" PowerPC kernels, which is the bug that > needs to be addressed.....
Well, it's more a question of who is grabbing minor numbers 64 and up on the TTY_MAJOR/TTY_AUX_MAJOR major numbers, and the answer is that is the driver for the Z8530-based serial ports, macserial.c. It does that because I based it on the zs.c serial driver for the Sparc, which also does that.
One approach would be to have a range of minor numbers for Z8530-based serial ports with names like /dev/ttyZn. That would be the easiest from a kernel developer's point of view, but I can foresee endless confusion with new users who don't realize that just because a powermac uses a different hardware chip for its serial ports from a PC, you have to use different names for the serial ports.
The other thing that the serial driver does is go probing I/O ports looking for serial devices. Perfectly reasonable on PCs, causes a machine check (and crash) on powermacs, unfortunately.
Maybe ultimately there could be a scheme for allocating serial minor numbers to serial device drivers at runtime, as the devices are found.
Paul.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |