Hi,
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 "normal" console registering
will become the default boot console instead. This way the unregister
call for the boot console in register_console() actually triggers and
the handover from the boot console to the real console device works
smoothly.
The patch also changes the x86 early_printk code to use this. The early
console is simply tagged as boot console, the disable_early_printk()
call is gone as it isn't needed any more.
cheers,
Gerd
--
Gerd Hoffmann <[email protected]>
---
arch/x86_64/kernel/early_printk.c | 20 +++++---------------
drivers/char/tty_io.c | 5 -----
kernel/printk.c | 26 ++++++++++++++++----------
3 files changed, 21 insertions(+), 30 deletions(-)
Index: paravirt-2.6.20-hg770/arch/x86_64/kernel/early_printk.c
===================================================================
--- paravirt-2.6.20-hg770.orig/arch/x86_64/kernel/early_printk.c
+++ paravirt-2.6.20-hg770/arch/x86_64/kernel/early_printk.c
@@ -244,22 +244,12 @@ static int __init setup_early_printk(cha
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");
- }
-}
-
Index: paravirt-2.6.20-hg770/kernel/printk.c
===================================================================
--- paravirt-2.6.20-hg770.orig/kernel/printk.c
+++ paravirt-2.6.20-hg770/kernel/printk.c
@@ -931,8 +931,16 @@ void register_console(struct console *co
{
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 *co
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 *c
}
}
- /* 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();
Index: paravirt-2.6.20-hg770/drivers/char/tty_io.c
===================================================================
--- paravirt-2.6.20-hg770.orig/drivers/char/tty_io.c
+++ paravirt-2.6.20-hg770/drivers/char/tty_io.c
@@ -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 *);
@@ -3881,9 +3879,6 @@ 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)();
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