Re: How do I choose an arbitrary minor number for my tty device?

From: Timur Tabi
Date: Mon Nov 22 2010 - 16:28:49 EST


Alan Cox wrote:
>> > Is there a way to do it in the driver itself? Getting the boot loader to
>> > identify the specific byte channel for stdout isn't trivial. It'd be nice if
>> > the driver could tell the tty layer, "BTW, this use this for the default console".

> You can - provide the required method in your console driver and it'll
> get used by /dev/console. Funnily enough a lot of other platform and
> consoles need that too.

Can you elaborate on that? What is the "required method"? My driver is mostly
working now, but I have to supply the command-line "console=ttyEHV73" in order
for the login prompt to show up. Unfortunately, there's no way for the boot
loader to know that the primary byte channel for stdout is #73, so I need a way
for the driver to tell the kernel this.

Also, if I have a /dev/ttyEHV76 entry for a byte channel that's not the primary
stdout tty, is the following supposed to work:

cat > /dev/ttyEHV76

That is, should I be able to use a TTY device as a normal character device,
where I can just write and read characters?

--
Timur Tabi
Linux kernel developer at Freescale

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