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serial: turn serial console suspend a boot rather than compile time option

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Currently, there's a CONFIG_DISABLE_CONSOLE_SUSPEND that allows one to stop
the serial console from being suspended when the rest of the machine goes
to sleep.  This is incredibly useful for debugging power management-related
things; however, having it as a compile-time option has proved to be
incredibly inconvenient for us (OLPC).  There are plenty of times that we
want serial console to not suspend, but for the most part we'd like serial
console to be suspended.

This drops CONFIG_DISABLE_CONSOLE_SUSPEND, and replaces it with a kernel
boot parameter (no_console_suspend).  By default, the serial console will
be suspended along with the rest of the system; by passing
'no_console_suspend' to the kernel during boot, serial console will remain
alive during suspend.

For now, this is pretty serial console specific; further fixes could be
applied to make this work for things like netconsole.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andres Salomon
2007-10-18 03:04:50 -07:00
committed by Linus Torvalds
parent 438e2ce68d
commit 8f4ce8c32f
7 changed files with 32 additions and 27 deletions
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11
kernel/power/Kconfig
View File

@@ -44,17 +44,6 @@ config PM_VERBOSE
---help---
This option enables verbose messages from the Power Management code.
config DISABLE_CONSOLE_SUSPEND
bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
depends on PM_DEBUG && PM_SLEEP
default n
---help---
This option turns off the console suspend mechanism that prevents
debug messages from reaching the console during the suspend/resume
operations. This may be helpful when debugging device drivers'
suspend/resume routines, but may itself lead to problems, for example
if netconsole is used.
config PM_TRACE
bool "Suspend/resume event tracing"
depends on PM_DEBUG && X86 && PM_SLEEP && EXPERIMENTAL

16
kernel/printk.c
View File

@@ -862,7 +862,16 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
return -1;
}
#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
int console_suspend_enabled = 1;
EXPORT_SYMBOL(console_suspend_enabled);
static int __init console_suspend_disable(char *str)
{
console_suspend_enabled = 0;
return 1;
}
__setup("no_console_suspend", console_suspend_disable);
/**
* suspend_console - suspend the console subsystem
*
@@ -870,6 +879,8 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha
*/
void suspend_console(void)
{
if (!console_suspend_enabled)
return;
printk("Suspending console(s)\n");
acquire_console_sem();
console_suspended = 1;
@@ -877,10 +888,11 @@ void suspend_console(void)
void resume_console(void)
{
if (!console_suspend_enabled)
return;
console_suspended = 0;
release_console_sem();
}
#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */
/**
* acquire_console_sem - lock the console system for exclusive use.