fblog is mainly useful during boot, reboot, panics and maintenance. In all
cases you often want to control which monitors are used for console
output. Moreover, in multi-seat environments it is desireable to reduce
system-overhead by not drawing the console to all framebuffers. Two
mechanisms to select framebuffers for fblog are added:
1) "active" module parameter: This parameter selects whether new
framebuffers are opened automatically. By default this is on, that is, all
framebuffers are automatically used by fblog during boot. By passing
fblog.active=0 you can deactivate this.
The init process can set this to 0 via
/sys/modules/fblog/parameters/active, too. However, this does not affect
already available and used framebuffers in any way.
2) "active" sysfs attribute for each fblog object. Reading this value
returns whether a framebuffer is currently active. Writing it opens/closes
the framebuffer. This allows runtime control which fbs are used. For
instance, init can set these to 0 after bootup.
Signed-off-by: David Herrmann <dh.herrm...@googlemail.com>
---
drivers/video/console/fblog.c | 50 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/drivers/video/console/fblog.c b/drivers/video/console/fblog.c
index 113be36..b490dba 100644
--- a/drivers/video/console/fblog.c
+++ b/drivers/video/console/fblog.c
@@ -42,6 +42,7 @@ struct fblog_fb {
static DEFINE_MUTEX(fblog_registration_lock);
static struct fblog_fb *fblog_fbs[FB_MAX];
+static bool active = 1;
#define to_fblog_dev(_d) container_of(_d, struct fblog_fb, dev)
@@ -116,6 +117,37 @@ static void fblog_close(struct fblog_fb *fb, bool
kill_dev, bool locked)
mutex_unlock(&fb->lock);
}
+static ssize_t fblog_dev_active_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct fblog_fb *fb = to_fblog_dev(dev);
+
+ return snprintf(buf, PAGE_SIZE, "%d\n",
+ !!test_bit(FBLOG_OPEN, &fb->flags));
+}
+
+static ssize_t fblog_dev_active_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf,
+ size_t count)
+{
+ struct fblog_fb *fb = to_fblog_dev(dev);
+ unsigned long num;
+ int ret = 0;
+
+ num = simple_strtoul(buf, NULL, 10);
+ if (num)
+ ret = fblog_open(fb, false);
+ else
+ fblog_close(fb, false, false);
+
+ return ret ? ret : count;
+}
+
+static DEVICE_ATTR(active, S_IRUGO | S_IWUSR | S_IWGRP, fblog_dev_active_show,
+ fblog_dev_active_store);
+
/*
* fblog framebuffer list
* The fblog_fbs[] array contains all currently registered framebuffers. If a
@@ -149,6 +181,7 @@ static void fblog_do_unregister(struct fb_info *info)
fblog_fbs[info->node] = NULL;
fblog_close(fb, true, false);
+ device_remove_file(&fb->dev, &dev_attr_active);
device_del(&fb->dev);
put_device(&fb->dev);
}
@@ -157,6 +190,7 @@ static void fblog_do_register(struct fb_info *info, bool
force)
{
struct fblog_fb *fb;
int ret;
+ bool do_open = true;
fb = fblog_fbs[info->node];
if (fb && fb->info != info) {
@@ -187,7 +221,18 @@ static void fblog_do_register(struct fb_info *info, bool
force)
return;
}
- fblog_open(fb, true);
+ ret = device_create_file(&fb->dev, &dev_attr_active);
+ if (ret) {
+ pr_err("fblog: cannot create sysfs entry");
+ /* do not open fb if we cannot create control file */
+ do_open = false;
+ }
+
+ if (!active)
+ do_open = false;
+
+ if (do_open)
+ fblog_open(fb, true);
}
static void fblog_register(struct fb_info *info, bool force)
@@ -314,6 +359,9 @@ static void __exit fblog_exit(void)
}
}
+module_param(active, bool, S_IRUGO);
+MODULE_PARM_DESC(active, "Activate fblog by default");
+
module_init(fblog_init);
module_exit(fblog_exit);
MODULE_LICENSE("GPL");
--
1.7.11.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
