Messages in this thread | | | Date | Sat, 10 Jun 2006 19:44:56 -0400 | From | "Jon Smirl" <> | Subject | Re: [PATCH 5/5] VT binding: Add new doc file describing the feature |
| |
On 6/10/06, Antonino A. Daplas <adaplas@gmail.com> wrote: > > I may be looking at the problem a little differently. I see the > > drivers like fb, vga, etc as registering with the console and saying > > they are capable of providing console services. I then see the console > > system as opening one of the registered devices. A driver is free to > > register/unregister whenever it wants to as long as it isn't open by > > the console system. Console can only open one driver at a time. > > No, this isn't true. You can have multiple console drivers active, > that's why you have a first and last parameter in take_over_console(). > Thus at boot time, the system driver will take consoles 0 - 63. > Later on when a driver loads, it can take over consoles 0 - 7, leaving > consoles 8 - 63 to the system driver. > > To put it another way, console drivers can register for consoles 0 - 63, > but the user may choose to use it only for consoles 0 - 7. > > This is another reason for the system driver, it makes the unbinding > behavior predictable. Without a system driver, guessing which driver > replaces the just unbound one may become just a tad bit confusing for > the typical user.
I find the whole console/tty layer to be quite confusing to talk about. I am mixing up console as in where printk goes and console the video card login device. The part about making everything equal was directed towards the printk output device.
I see now that you can have tty0-7 assigned to a different console driver than tty8-63. Why do I want to do this? Why do we need 64 predefined tty devices?
Googling around the only example I could find was someone with a VGA card and a Hercules card. They setup 8 consoles on each card.
> > Over time it would nice if these all merged to a single > > interchangeable interface. I would really like to be able to > > dynamically switch to serial/net while debugging a video driver. Is > > there some fundamental reason why these can't be merged? > > It's already possible to redirect the system messages to two different > console classes, ie with the boot parameter: > > console=tty0,ttyS0 /* direct output to VT and serial console */ > > And you can already choose the console you want by adjusting /etc/inittab.
How can I change where printk are going at run-time? I didn't know you could do that.
-- Jon Smirl jonsmirl@gmail.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |