# \[RFC 5/8\] kmsg: device support in mem class

- From: Marcin Niesluchowski \<hidden\>
- Date: 2015-07-03 10:51:57 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2015/07/4527045
- Thread: https://ratatoskr.run/linux-api/2015/07/4527040/t.md

```text
Mem class is current class in which kmsg device is holded in.

Mem class is exteded by kmsg_sys devices handling.

Signed-off-by: Marcin Niesluchowski <redacted>
---
 drivers/char/mem.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index e518040..8d5ba0d 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -815,7 +815,11 @@ static int memory_open(struct inode *inode, struct file *filp)
 
 	minor = iminor(inode);
 	if (minor >= ARRAY_SIZE(devlist))
+#ifdef CONFIG_PRINTK
+		minor = KMSG_MINOR;
+#else
 		return -ENXIO;
+#endif
 
 	dev = &devlist[minor];
 	if (!dev->fops)
@@ -837,8 +841,20 @@ static const struct file_operations memory_fops = {
 
 static char *mem_devnode(struct device *dev, umode_t *mode)
 {
-	if (mode && devlist[MINOR(dev->devt)].mode)
-		*mode = devlist[MINOR(dev->devt)].mode;
+	int minor;
+
+	if (!mode)
+		return NULL;
+
+	minor = MINOR(dev->devt);
+
+#ifdef CONFIG_PRINTK
+	if (minor >= ARRAY_SIZE(devlist))
+		kmsg_sys_mode(minor, mode);
+	else
+#endif
+		if (devlist[minor].mode)
+			*mode = devlist[minor].mode;
 	return NULL;
 }
 
-- 
1.9.1

```