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The disable_early_printk() call is obsolete with that patch, explicitly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>

1 files changed, 5 insertions, 15 deletions

diff --git a/arch/x86_64/kernel/early_printk.c b/arch/x86_64/kernel/early_printk.c
index 92213d2b7c11..56eaa259782b 100644
--- a/arch/x86_64/kernel/early_printk.c
+++ b/arch/x86_64/kernel/early_printk.c
@@ -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");
-        }
-}
-