Re: Christmas list for the kernel

Russell King
2005-11-23T16:05:30Z

On Wed, Nov 23, 2005 at 04:56:50PM +0100, Marc Koschewski wrote:
> * Jon Smirl <jonsmirl@gmail.com> [2005-11-23 10:12:58 -0500]:
>
> > On 11/23/05, Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> > > > Plus I have 64 tty devices. Couldn't the tty devices be created
> > > > dynamically as they are consumed? Same for the loop and ram devices?
> > >
> > > You do realise that the dynamic device creation for those 64 console
> > > devices is done via the console device being _opened_ by userspace?
> > >
> > > Hence, if the device doesn't exist in userspace, it can't be created
> > > for userspace to open it to create the device via udev. Have you
> > > noticed a catch-22 with that statement?
> >
> > Couldn't we create tty0-3 and then when one of those gets opened,
> > create tty4, and so on? Then there would always be two or three more
> > tty devices than there are open tty devices.
> >
>
> How does that work when you ie. have tty0, tty1, tty2, tty3 per default,
> open tty4, tty5, tty6 and the close tty4? And what if you then open
> another? Will it be tty4 oder tty7? If so, what if the maximum numer is
> reached even if only 3 ttys are left open?

And what if you want consoles on 1-6 and syslog messages on tty12?

Also, remember that when init starts the gettys on tty1-N, they're
started in parallel, so you will end up with the gettys opening those
in a random order.

Therefore, you can not infer that if tty1 has been opened, tty2 will
be next, followed by tty3 and then tty4, etc.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core