[PATCH] suspend-to-ram: allow video options to be set at runtime

Currently, acpi video options can only be set on kernel command line.  That's
little inflexible; I'd like userland s2ram application that just works, and
modifying kernel command line according to whitelist is not fun.  It is better
to just allow s2ram application to set video options just before suspend
(according to the whitelist).

This implements sysctl to allow setting suspend video options without reboot.

(akpm: Documentation updates for this new sysctl are pending..)
Signed-off-by: Pavel Machek <pavel@suse.cz>
Cc: "Brown, Len" <len.brown@intel.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/sysctl/kernel.txt

@@ -16,6 +16,7 @@ before actually making adjustments.
 
 Currently, these files might (depending on your configuration)
 show up in /proc/sys/kernel:
+- acpi_video_flags
 - acct
 - core_pattern
 - core_uses_pid
@@ -57,6 +58,15 @@ show up in /proc/sys/kernel:
 
 ==============================================================
 
+acpi_video_flags:
+
+flags
+
+See Doc*/kernel/power/video.txt, it allows mode of video boot to be
+set during run time.
+
+==============================================================
+
 acct:
 
 highwater lowwater frequency

include/linux/acpi.h

@@ -427,7 +427,8 @@ extern int acpi_mp_config;
 extern struct acpi_table_mcfg_config *pci_mmcfg_config;
 extern int pci_mmcfg_config_num;
 
-extern int sbf_port ;
+extern int sbf_port;
+extern unsigned long acpi_video_flags;
 
 #else	/* !CONFIG_ACPI */
 

include/linux/sysctl.h

@@ -146,6 +146,7 @@ enum
 	KERN_RANDOMIZE=68, /* int: randomize virtual address space */
 	KERN_SETUID_DUMPABLE=69, /* int: behaviour of dumps for setuid core */
 	KERN_SPIN_RETRY=70,	/* int: number of spinlock retries */
+	KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
 };
 
 

kernel/sysctl.c

@@ -44,14 +44,12 @@
 #include <linux/limits.h>
 #include <linux/dcache.h>
 #include <linux/syscalls.h>
+#include <linux/nfs_fs.h>
+#include <linux/acpi.h>
 
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 
-#ifdef CONFIG_ROOT_NFS
-#include <linux/nfs_fs.h>
-#endif
-
 #if defined(CONFIG_SYSCTL)
 
 /* External variables not in a header file. */
@@ -655,6 +653,16 @@ static ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#endif
+#ifdef CONFIG_ACPI_SLEEP
+	{
+		.ctl_name	= KERN_ACPI_VIDEO_FLAGS,
+		.procname	= "acpi_video_flags",
+		.data		= &acpi_video_flags,
+		.maxlen		= sizeof (unsigned long),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 #endif
 	{ .ctl_name = 0 }
 };