Re: Christmas list for the kernel

From: Russell King
Date: Wed Nov 23 2005 - 11:05:04 EST

On Wed, Nov 23, 2005 at 04:56:50PM +0100, Marc Koschewski wrote:
> * Jon Smirl <jonsmirl@xxxxxxxxx> [2005-11-23 10:12:58 -0500]:
> > On 11/23/05, Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> 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 -
maintainer of: 2.6 Serial core
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