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Fixes and cleanups for earlyprintk aka boot console

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The console subsystem already has an idea of a boot console, using the
CON_BOOT flag.  The implementation has some flaws though.  The major
problem is that presence of a boot console makes register_console() ignore
any other console devices (unless explicitly specified on the kernel
command line).

This patch fixes the console selection code to *not* consider a boot
console a full-featured one, so the first non-boot console registering will
become the default console instead.  This way the unregister call for the
boot console in the register_console() function actually triggers and the
handover from the boot console to the real console device works smoothly.
Added a printk for the handover, so you know which console device the
output goes to when the boot console stops printing messages.

The disable_early_printk() call is obsolete with that patch, explicitly
disabling the early console isn't needed any more as it works automagically
with that patch.

I've walked through the tree, dropped all disable_early_printk() instances
found below arch/ and tagged the consoles with CON_BOOT if needed.  The
code is tested on x86, sh (thanks to Paul) and mips (thanks to Ralf).

Changes to last version: Rediffed against -rc3, adapted to mips cleanups by
Ralf, fixed "udbg-immortal" cmd line arg on powerpc.

Signed-off-by: Gerd Hoffmann <kraxel@exsuse.de>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Gerd Hoffmann 2007-05-08 00:26:49 -07:00 committed by Linus Torvalds
parent 6ae9200f2c
commit 69331af79c
9 changed files with 35 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/alpha/kernel/setup.c
View File

@ -744,15 +744,6 @@ setup_arch(char **cmdline_p)
paging_init();
}
void __init
disable_early_printk(void)
{
if (alpha_using_srm && srmcons_output) {
unregister_srm_console();
srmcons_output = 0;
}
}
static char sys_unknown[] = "Unknown";
static char systype_names[][16] = {
"0",

2
arch/alpha/kernel/srmcons.c
View File

@ -300,7 +300,7 @@ static struct console srmcons = {
.write = srm_console_write,
.device = srm_console_device,
.setup = srm_console_setup,
.flags = CON_PRINTBUFFER,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};

5
arch/mips/kernel/early_printk.c
View File

@ -33,8 +33,3 @@ void __init setup_early_printk(void)
{
register_console(&early_console);
}
void __init disable_early_printk(void)
{
unregister_console(&early_console);
}

19
arch/powerpc/kernel/udbg.c
View File

@ -142,29 +142,22 @@ static void udbg_console_write(struct console *con, const char *s,
static struct console udbg_console = {
.name = "udbg",
.write = udbg_console_write,
.flags = CON_PRINTBUFFER | CON_ENABLED,
.flags = CON_PRINTBUFFER | CON_ENABLED | CON_BOOT,
.index = -1,
};
static int early_console_initialized;
void __init disable_early_printk(void)
{
if (!early_console_initialized)
return;
if (strstr(boot_command_line, "udbg-immortal")) {
printk(KERN_INFO "early console immortal !\n");
return;
}
unregister_console(&udbg_console);
early_console_initialized = 0;
}
/* called by setup_system */
void register_early_udbg_console(void)
{
if (early_console_initialized)
return;
if (strstr(boot_command_line, "udbg-immortal")) {
printk(KERN_INFO "early console immortal !\n");
udbg_console.flags &= ~CON_BOOT;
}
early_console_initialized = 1;
register_console(&udbg_console);
}

18
arch/sh/kernel/early_printk.c
View File

@ -192,20 +192,14 @@ int __init setup_early_printk(char *buf)
}
#endif
if (likely(early_console))
if (likely(early_console)) {
if (keep_early)
early_console->flags &= ~CON_BOOT;
else
early_console->flags |= CON_BOOT;
register_console(early_console);
}
return 0;
}
early_param("earlyprintk", setup_early_printk);
void __init disable_early_printk(void)
{
if (!early_console_initialized || !early_console)
return;
if (!keep_early) {
printk("disabling early console\n");
unregister_console(early_console);
} else
printk("keeping early console\n");
}

8
arch/sh64/kernel/early_printk.c
View File

@ -79,7 +79,7 @@ static struct console sh_console = {
.name = "scifcon",
.write = sh_console_write,
.setup = sh_console_setup,
.flags = CON_PRINTBUFFER,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};
@ -97,9 +97,3 @@ void __init enable_early_printk(void)
register_console(&sh_console);
}
void disable_early_printk(void)
{
unregister_console(&sh_console);
}

20
arch/x86_64/kernel/early_printk.c
View File

@ -243,22 +243,12 @@ static int __init setup_early_printk(char *buf)
early_console = &simnow_console;
keep_early = 1;
}
if (keep_early)
early_console->flags &= ~CON_BOOT;
else
early_console->flags |= CON_BOOT;
register_console(early_console);
return 0;
}
early_param("earlyprintk", setup_early_printk);
void __init disable_early_printk(void)
{
if (!early_console_initialized || !early_console)
return;
if (!keep_early) {
printk("disabling early console\n");
unregister_console(early_console);
early_console_initialized = 0;
} else {
printk("keeping early console\n");
}
}

5
drivers/char/tty_io.c
View File

@ -141,8 +141,6 @@ static DECLARE_MUTEX(allocated_ptys_lock);
static int ptmx_open(struct inode *, struct file *);
#endif
extern void disable_early_printk(void);
static void initialize_tty_struct(struct tty_struct *tty);
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
@ -3897,9 +3895,6 @@ void __init console_init(void)
* set up the console device so that later boot sequences can
* inform about problems etc..
*/
#ifdef CONFIG_EARLY_PRINTK
disable_early_printk();
#endif
call = __con_initcall_start;
while (call < __con_initcall_end) {
(*call)();

26
kernel/printk.c
View File

@ -931,8 +931,16 @@ void register_console(struct console *console)
{
int i;
unsigned long flags;
struct console *bootconsole = NULL;
if (preferred_console < 0)
if (console_drivers) {
if (console->flags & CON_BOOT)
return;
if (console_drivers->flags & CON_BOOT)
bootconsole = console_drivers;
}
if (preferred_console < 0 || bootconsole || !console_drivers)
preferred_console = selected_console;
/*
@ -978,8 +986,11 @@ void register_console(struct console *console)
if (!(console->flags & CON_ENABLED))
return;
if (console_drivers && (console_drivers->flags & CON_BOOT)) {
unregister_console(console_drivers);
if (bootconsole) {
printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n",
bootconsole->name, bootconsole->index,
console->name, console->index);
unregister_console(bootconsole);
console->flags &= ~CON_PRINTBUFFER;
}
@ -1030,16 +1041,11 @@ int unregister_console(struct console *console)
}
}
/* If last console is removed, we re-enable picking the first
* one that gets registered. Without that, pmac early boot console
* would prevent fbcon from taking over.
*
/*
* If this isn't the last console and it has CON_CONSDEV set, we
* need to set it on the next preferred console.
*/
if (console_drivers == NULL)
preferred_console = selected_console;
else if (console->flags & CON_CONSDEV)
if (console_drivers != NULL && console->flags & CON_CONSDEV)
console_drivers->flags |= CON_CONSDEV;
release_console_sem();