From: Matthew Wilcox CON_BOOT is like early printk in that it allows for output really early on. It's better than early printk because it unregisters automatically when a real console is initialised. So if you don't get consoles registering in console_init, there isn't a huge delay between the boot console unregistering and the real console starting. This is the case on PA-RISC where we have serial ports that aren't discovered until the PCI bus has been walked. I think all the current early printk users could be converted to this scheme with a minimal amount of effort. Signed-off-by: Andrew Morton --- 25-akpm/include/linux/console.h | 1 + 25-akpm/kernel/printk.c | 5 +++++ 2 files changed, 6 insertions(+) diff -puN include/linux/console.h~new-console-flag-con_boot include/linux/console.h --- 25/include/linux/console.h~new-console-flag-con_boot 2005-03-15 22:47:16.000000000 -0800 +++ 25-akpm/include/linux/console.h 2005-03-15 22:47:16.000000000 -0800 @@ -84,6 +84,7 @@ void give_up_console(const struct consw #define CON_PRINTBUFFER (1) #define CON_CONSDEV (2) /* Last on the command line */ #define CON_ENABLED (4) +#define CON_BOOT (8) struct console { diff -puN kernel/printk.c~new-console-flag-con_boot kernel/printk.c --- 25/kernel/printk.c~new-console-flag-con_boot 2005-03-15 22:47:16.000000000 -0800 +++ 25-akpm/kernel/printk.c 2005-03-15 22:47:16.000000000 -0800 @@ -861,6 +861,11 @@ void register_console(struct console * c if (!(console->flags & CON_ENABLED)) return; + if (console_drivers && (console_drivers->flags & CON_BOOT)) { + unregister_console(console_drivers); + console->flags &= ~CON_PRINTBUFFER; + } + /* * Put this console in the list - keep the * preferred driver at the head of the list. _