Fixes and cleanups for earlyprintk aka boot console
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The disable_early_printk() call is obsolete with that patch, explicitly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>
diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index d352c2b..915f263 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -744,15 +744,6 @@
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",
diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
index 85a821a..930cedc 100644
--- a/arch/alpha/kernel/srmcons.c
+++ b/arch/alpha/kernel/srmcons.c
@@ -300,7 +300,7 @@
.write = srm_console_write,
.device = srm_console_device,
.setup = srm_console_setup,
- .flags = CON_PRINTBUFFER,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};
diff --git a/arch/mips/kernel/early_printk.c b/arch/mips/kernel/early_printk.c
index 304efdc..4fa54b2 100644
--- a/arch/mips/kernel/early_printk.c
+++ b/arch/mips/kernel/early_printk.c
@@ -33,8 +33,3 @@
{
register_console(&early_console);
}
-
-void __init disable_early_printk(void)
-{
- unregister_console(&early_console);
-}
diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index 7e09718..147a2d8 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -142,29 +142,22 @@
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);
}
diff --git a/arch/sh/kernel/early_printk.c b/arch/sh/kernel/early_printk.c
index 9048c03..9833493 100644
--- a/arch/sh/kernel/early_printk.c
+++ b/arch/sh/kernel/early_printk.c
@@ -192,20 +192,14 @@
}
#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");
-}
diff --git a/arch/sh64/kernel/early_printk.c b/arch/sh64/kernel/early_printk.c
index 8c8a76e..4f91311 100644
--- a/arch/sh64/kernel/early_printk.c
+++ b/arch/sh64/kernel/early_printk.c
@@ -79,7 +79,7 @@
.name = "scifcon",
.write = sh_console_write,
.setup = sh_console_setup,
- .flags = CON_PRINTBUFFER,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};
@@ -97,9 +97,3 @@
register_console(&sh_console);
}
-
-void disable_early_printk(void)
-{
- unregister_console(&sh_console);
-}
-
diff --git a/arch/x86_64/kernel/early_printk.c b/arch/x86_64/kernel/early_printk.c
index 92213d2..56eaa25 100644
--- a/arch/x86_64/kernel/early_printk.c
+++ b/arch/x86_64/kernel/early_printk.c
@@ -243,22 +243,12 @@
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");
- }
-}
-
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 389da36..730cbd2 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -141,8 +141,6 @@
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 @@
* 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)();
diff --git a/kernel/printk.c b/kernel/printk.c
index 4b47e59..c4c5a29 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -931,8 +931,16 @@
{
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 @@
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 @@
}
}
- /* 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();