2003-02-11 14:34:23

by Andries E. Brouwer

Subject: struct tty_driver

Ted, I wondered:

Looking at 2.5.60 I see

struct tty_struct {
int magic;
struct tty_driver driver;
...

and it looks like this struct tty_driver is never modified.
Since it is rather large, why not replace it by
struct tty_driver *driver;
?

As it is now, the initialization in init_dev() does
tty->driver = *driver;
just duplicating constant data.

Is this a historical relict, or does this duplication have a function?

Andries

2003-02-12 18:43:14

by Theodore Ts'o

Subject: Re: struct tty_driver

On Tue, Feb 11, 2003 at 03:44:07PM +0100, [email protected] wrote:
> Ted, I wondered:
>
> Looking at 2.5.60 I see
>
> struct tty_struct {
> int magic;
> struct tty_driver driver;
> ...
>
> and it looks like this struct tty_driver is never modified.
> Since it is rather large, why not replace it by
> struct tty_driver *driver;
> ?
>
> As it is now, the initialization in init_dev() does
> tty->driver = *driver;
> just duplicating constant data.
>
> Is this a historical relict, or does this duplication have a function?

Nope. The tty->ldisc should also be made into a pointer as well.
It's a historic relict; it's been a very, very long time since there's
been any variable data in the driver or ldisc structures.

- Ted