Re: [PATCH] VT driver/char/console.c, kernel 2.4.22

[Baptiste Malguy]

Willy Tarreau a écrit :

> On Sat, Nov 29, 2003 at 12:49:50AM +0100, Baptiste Malguy wrote:
>
>  
>
> > In relation to this patch, I want to say that many many websites, FAQs, 
> > ... say that you must
> > have something like console="/dev/ttyX CONSOLE=/dev/ttyN" to redirect 
> > the kernel and init
> > messages.
> >
> > About 'CONSOLE=', that's true because this is a environment variable 
> > that /sbin/init obtains.
> > About 'console=', it's completly wrong ! 'console=' expects a driver 
> > name (example: "tty",
> > "tty1", "ttyS0"), not device file name. Only the Linux source code 
> > reading and a few websites
> > says the right usage of 'console='.
> >    
>
> If there really are FAQ reporting this, it might be simpler to make the
> kernel accept /dev/XXX than to try to fix all FAQs, and it would be more
> intuitive to people who type on lilo command line.
>  
I guess you are right. However, all I've done (and again, essentially, 
using someone else
code) is to fix of bug. Changing the way the 'console=' argument works 
is more a
design stuff.

If all the console drivers' names are based on the device file name 
(that is "tty" for "/dev/tty1",
ort "/dev/tty2", ...) it can be easily done by dropping "/dev/" from the 
'console=' argument value, in
one C file. However, a device file name can be anything you want. So the 
"/dev/" wouldn't work.

I don't know if that's the good way to do it. Maybe a more complete 
work, like looking at the device file,
its major and minor and the corresponding driver, would be a better idea.

> You'd better send an "unified diff" (diff -u) which includes one level of
> kernel directory. You diff then starts like this :
> --- linux-2.4.22/drivers/char/console
> +++ linux-2.4.22-bm1/drivers/char/console
>  
Yes, sure, I read that before and did not even do that .... I'd better 
sleep more at night :)
Here it comes now.

I have tested with 'vga=normal' and 'vga=792'. That's fine for me. 
However, I may have not taken in
consideration some locks required. I let interested people test for a 
few days before sending to Marcello.

Thank you for your comments.

--
Baptiste Malguy - http://baptiste.malguy.net
Ingénieur en informatique libre

--- linux-2.4.22/drivers/char/console.c	2002-11-29 00:53:12.000000000 +0100
+++ work/linux-2.4.22-bm1/drivers/char/console.c	2003-11-28 17:12:47.000000000 +0100
@@ -144,6 +144,7 @@
 static int con_open(struct tty_struct *, struct file *);
 static void vc_init(unsigned int console, unsigned int rows,
 		    unsigned int cols, int do_clear);
+static void con_setup_vt(unsigned int currcons);
 static void blank_screen(unsigned long dummy);
 static void gotoxy(int currcons, int new_x, int new_y);
 static void save_cur(int currcons);
@@ -2178,10 +2179,25 @@
 	return MKDEV(TTY_MAJOR, c->index ? c->index : fg_console + 1);
 }
 
+int vt_console_setup(struct console *co, char *options)
+{
+	if (co == NULL)
+		return -1;
+	
+	if (co->index > 0 &&
+	    co->index < MAX_NR_CONSOLES) {
+		con_setup_vt(co->index - 1);
+		kmsg_redirect = co->index;
+	}
+
+	return 0;
+}
+
 struct console vt_console_driver = {
 	name:		"tty",
 	write:		vt_console_print,
 	device:		vt_console_device,
+	setup:		vt_console_setup,
 	unblank:	unblank_screen,
 	flags:		CON_PRINTBUFFER,
 	index:		-1,
@@ -2432,6 +2448,24 @@
 }
 
 /*
+ * Setup a new VT
+ */
+static void __init con_setup_vt(unsigned int currcons)
+{
+	if (vc_cons[currcons].d) return;
+	
+	vc_cons[currcons].d = (struct vc_data *)
+		alloc_bootmem(sizeof(struct vc_data));
+	vt_cons[currcons] = (struct vt_struct *)
+		alloc_bootmem(sizeof(struct vt_struct));
+	visual_init(currcons, 1);
+	screenbuf = (unsigned short *) alloc_bootmem(screenbuf_size);
+	kmalloced = 0;
+	vc_init(currcons, video_num_lines, video_num_columns, 
+		currcons || !sw->con_save_screen);
+}
+
+/*
  * This routine initializes console interrupts, and does nothing
  * else. If you want the screen to clear, call tty_write with
  * the appropriate escape-sequence.
@@ -2498,15 +2532,7 @@
 	 * kmalloc is not running yet - we use the bootmem allocator.
 	 */
 	for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
-		vc_cons[currcons].d = (struct vc_data *)
-				alloc_bootmem(sizeof(struct vc_data));
-		vt_cons[currcons] = (struct vt_struct *)
-				alloc_bootmem(sizeof(struct vt_struct));
-		visual_init(currcons, 1);
-		screenbuf = (unsigned short *) alloc_bootmem(screenbuf_size);
-		kmalloced = 0;
-		vc_init(currcons, video_num_lines, video_num_columns, 
-			currcons || !sw->con_save_screen);
+		con_setup_vt(currcons); 
 	}
 	currcons = fg_console = 0;
 	master_display_fg = vc_cons[currcons].d;