linux/kernel/printk.c, branch v2.6.32

printk: add printk_delay to make messages readable for some scenarios

2009-09-23T14:39:28Z

When syslog is not possible, at the same time there's no serial/net console available, it will be hard to read the printk messages. For example oops/panic/warning messages in shutdown phase. Add a printk delay feature, we can make each printk message delay some milliseconds. Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay The value range from 0 - 10000, default value is 0 [akpm@linux-foundation.org: fix a few things] Signed-off-by: Dave Young Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

printk boot_delay: rename printk_delay_msec to loops_per_msec

2009-09-23T14:39:28Z

Rename `printk_delay_msec' to `loops_per_msec', because the patch "printk: add printk_delay to make messages readable for some scenarios" wishes to more appropriately use the `printk_delay_msec' identifier. [akpm@linux-foundation.org: add a comment] Signed-off-by: Dave Young Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cleanup console_print()

2009-09-15T00:41:42Z

console_print() is an old legacy interface mostly unused in the entire kernel tree. It's best to clean up its existing use and let developers use their own implementation of it as they feel fit. Signed-off-by: Anirban Sinha Signed-off-by: Linus Torvalds

printk: Fix "printk: Enable the use of more than one CON_BOOT (early console)"

2009-08-08T16:27:37Z

Don't return when we find the first bootconsole - it can leave other bootconsoles still installed, and they can be used and cause problems later (if they are in the init section, and eventually released), and cause problems. Make sure we remove all of them. Signed-off-by: Sonic Zhang Signed-off-by: Robin Getz Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar

printk: Restore previous console_loglevel when re-enabling logging

2009-07-10T14:02:23Z

When logging to console is disabled from userspace using klogctl() and later re-enabled, console_loglevel gets set to the default log level instead to the previous value. This means that if the kernel was booted with 'quiet', the boot is suddenly no longer quiet after logging to console gets re-enabled. Save the current console_loglevel when logging is disabled and restore to that value. If the log level is set to a specific value while disabled, this is interpreted as an implicit re-enabling of the logging. The problem that prompted this patch is described in: http://lkml.org/lkml/2009/6/28/234 There are two variations possible on the patch below: 1) If klogctl(7) is called while logging is not disabled, then set level to default (partially preserving current functionality): case 7: /* Enable logging to console */ - console_loglevel = default_console_loglevel; + if (saved_console_loglevel == -1) + console_loglevel = default_console_loglevel; + else { + console_loglevel = saved_console_loglevel; + saved_console_loglevel = -1; + } 2) If klogctl(8) is called while logging is disabled, then don't enable logging, but remember the requested value for when logging does get enabled again: case 8: /* Set level of messages printed to console */ [...] - console_loglevel = len; + if (saved_console_loglevel == -1) + console_loglevel = len; + else + saved_console_loglevel = len; Yet another option would be to ignore the request. Signed-off-by: Frans Pop Cc: cryptsetup@packages.debian.org Cc: Andrew Morton Cc: Linus Torvalds LKML-Reference: <200907061331.49930.elendil@planet.nl> Signed-off-by: Ingo Molnar

printk: Ensure that "console enabled" messages are printed on the console

2009-07-10T10:24:47Z

Today, when a console is registered without CON_PRINTBUFFER, end users never see the announcement of it being added, and never know if they missed something, if the console is really at the start or not, and just leads to general confusion. This re-orders existing code, to make sure the console is added, before the "console [%s%d] enabled" is printed out - ensuring that this message is _always_ seen. This has the desired/intended side effect of making sure that "console enabled:" messages are printed on the bootconsole, and the real console. This does cause the same line is printed twice if the bootconsole and real console are the same device, but if they are on different devices, the message is printed to both consoles. Signed-off-by : Robin Getz Cc: "Andrew Morton" Cc: "Linus Torvalds" LKML-Reference: <200907091308.37370.rgetz@blackfin.uclinux.org> Signed-off-by: Ingo Molnar

printk: Enable the use of more than one CON_BOOT (early console)

2009-07-03T08:10:43Z

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

printk: Add KERN_DEFAULT printk log-level

2009-06-16T18:02:28Z

This adds a KERN_DEFAULT loglevel marker, for when you cannot decide which loglevel you want, and just want to keep an existing printk with the default loglevel. The difference between having KERN_DEFAULT and having no log-level marker at all is two-fold: - having the log-level marker will now force a new-line if the previous printout had not added one (perhaps because it forgot, but perhaps because it expected a continuation) - having a log-level marker is required if you are printing out a message that otherwise itself could perhaps otherwise be mistaken for a log-level. Signed-of-by: Linus Torvalds

printk: clean up handling of log-levels and newlines

2009-06-16T17:57:02Z

It used to be that we would only look at the log-level in a printk() after explicit newlines, which can cause annoying problems when the previous printk() did not end with a '\n'. In that case, the log-level marker would be just printed out in the middle of the line, and be seen as just noise rather than change the logging level. This changes things to always look at the log-level in the first bytes of the printout. If a log level marker is found, it is always used as the log-level. Additionally, if no newline existed, one is added (unless the log-level is the explicit KERN_CONT marker, to explicitly show that it's a continuation of a previous line). Acked-by: Arjan van de Ven Signed-off-by: Linus Torvalds

Merge branch 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-04-05T17:23:25Z

* 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: printk: correct the behavior of printk_timed_ratelimit() vsprintf: unify the format decoding layer for its 3 users, cleanup fix regression from "vsprintf: unify the format decoding layer for its 3 users" vsprintf: fix bug in negative value printing vsprintf: unify the format decoding layer for its 3 users vsprintf: add binary printf printk: introduce printk_once() Fix trivial conflicts (printk_once vs log_buf_kexec_setup() added near each other) in include/linux/kernel.h.