From 69331af79cf29e26d1231152a172a1a10c2df511 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 8 May 2007 00:26:49 -0700 Subject: 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 The disable_early_printk() call is obsolete with that patch, explicitly disabling the early console isn't needed any more as it works automagically with that patch.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 Acked-by: Paul Mundt Acked-by: Ralf Baechle Cc: Andi Kleen Cc: Alan Cox Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Jeremy Fitzhardinge Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/printk.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'kernel/printk.c') diff --git a/kernel/printk.c b/kernel/printk.c index 4b47e59248d..c4c5a29a7be 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -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(); -- cgit v1.2.3