Assuring that a device node exists for extended error reporting

6.10 LPAR mode z/VM guest KVM guest

Applications that use the extended error reporting facility require a character device to access the extended error data.

Before you begin

You need the device node only if you want to support applications that use the extended error reporting for ECKD type DASD.
You need a DASD device driver that has been built with support for extended error reporting
Your distribution might create the required device node for you, for example, with udev.
To check if there is already a node issue:
```
# find / -name dasd_eer
```
Typically, the node is called /dev/dasd_eer.

If there is no device node, perform the following steps to create one:

Find out the major and minor number for your monitor device by reading the dev attribute of the device representation in sysfs:
```
# cat /sys/class/misc/dasd_eer/dev
```
The value of the dev attribute is of the form <major>:<minor>.
Create the device node by issuing a command of the form:
```
# mknod <node> c <major> <minor>
```
where <node> is your device node.

To create a device node /dev/dasd_eer:

# cat /sys/class/misc/dasd_eer/dev
10:61
# mknod /dev/dasd_eer c 10 61

In the example, the major number was 10 and the minor 61.