Re: [RFC PATCH 29/35] Add the Xen virtual console driver.

Andi Kleen
2006-03-22T15:03:57Z

On Wednesday 22 March 2006 07:31, Chris Wright wrote:

Basically it's the same thing as the buffer in printk.c except
that it does input too.

You could safe a lot of code by just teaching the Hypervisor
about that one. Not sure it is fully practical though,

> --- xen-subarch-2.6.orig/drivers/char/tty_io.c
> +++ xen-subarch-2.6/drivers/char/tty_io.c
> @@ -132,6 +132,8 @@ LIST_HEAD(tty_drivers); /* linked list
> vt.c for deeply disgusting hack reasons */
> DECLARE_MUTEX(tty_sem);
>
> +int console_use_vt = 1;

This doesn't have anything to do with early console.

Why is it needed? Looks like a ugly hack.

> +#define __RETCODE 0

What is that?

> +/*** Useful function for console debugging -- goes straight to Xen. ***/
> +asmlinkage int xprintk(const char *fmt, ...)

In normal Linux this is called early_printk()

> +{
> + va_list args;
> + int printk_len;
> + static char printk_buf[1024];

Who does the locking here?

-Andi