From: Robin Getz Date: Thu, 2 Jul 2009 01:08:37 +0000 (-0400) Subject: printk: Enable the use of more than one CON_BOOT (early console) X-Git-Tag: v2.6.32-rc1~725^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4d09161196c9a836eacea4b36e2f217bc34894cf;p=pandora-kernel.git printk: Enable the use of more than one CON_BOOT (early console) Today, register_console() assumes the following usage: - The first console to register with a flag set to CON_BOOT is the one and only bootconsole. - If another register_console() is called with an additional CON_BOOT, it is silently rejected. - As soon as a console without the CON_BOOT set calls registers the bootconsole is automatically unregistered. - Once there is a "real" console - register_console() will silently reject any consoles with it's CON_BOOT flag set. In many systems (alpha, blackfin, microblaze, mips, powerpc, sh, & x86), there are early_printk implementations, which use the CON_BOOT which come out serial ports, vga, usb, & memory buffers. In many embedded systems, it would be nice to have two bootconsoles - in case the primary fails, you always have access to a backup memory buffer - but this requires at least two CON_BOOT consoles... This patch enables that functionality. With the change applied, on boot you get (if you try to re-enable a boot console after the "real" console has been registered): root:/> dmesg | grep console bootconsole [early_shadow0] enabled bootconsole [early_BFuart0] enabled Kernel command line: root=/dev/mtdblock0 rw earlyprintk=serial,uart0,57600 console=ttyBF0,57600 nmi_debug=regs console handover:boot [early_BFuart0] boot [early_shadow0] -> real [ttyBF0] Too late to register bootconsole early_shadow0 or: root:/> dmesg | grep console Kernel command line: root=/dev/mtdblock0 rw console=ttyBF0,57600 console [ttyBF0] enabled Signed-off-by: Robin Getz Cc: "Linus Torvalds" Cc: "Andrew Morton" Cc: "Mike Frysinger" Cc: "Paul Mundt" LKML-Reference: <200907012108.38030.rgetz@blackfin.uclinux.org> Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed