Booting from a DASD

Ubuntu 22.04 LTS z/VM guest

Boot Linux™ by issuing the IPL command with a DASD boot device. You can specify additional parameters with the IPL command.

Before you begin

You need a DASD boot device prepared with zipl.

Procedure

Perform these steps to start the boot process:

Establish a CMS or CP session with the z/VM® guest virtual machine where you want to boot Linux.
Ensure that the boot device is accessible to your z/VM guest virtual machine.
Issue a command of this form:
```
#cp i <devno> clear loadparm <n> parm <kernel_parameters>
```
where:

<devno>

specifies the device number of the boot device as seen by the guest.

loadparm <n>

is applicable to menu configurations only. Omit this parameter if you are not working with a menu configuration.
Configuration number 0 specifies the default configuration. Depending on the menu configuration, omitting this option might display the menu or select the default configuration. Specifying prompt instead of a configuration number forces the menu to be displayed.

When the menu is displayed, you can specify additional kernel parameters. These additional kernel parameters are appended to the parameters you might have provided in a parameter file. The combined parameter string must not exceed 895 bytes.

parm <kernel_parameters>

is an optional 64-byte string of kernel parameters to be concatenated to the end of the existing kernel parameters used by your boot configuration.

DASD menu configuration example for z/VM

Use the VI VMSG z/VM CP command to choose a boot configuration from a menu configuration.

This example illustrates how menu2 in the sample configuration file in Figure 1 is displayed on the z/VM guest virtual machine console:

00: zIPL interactive boot menu
00:
00:  0. default (boot1)
00:
00:  1. boot1
00:  2. boot3
00:
00: Note: VM users please use '#cp vi vmsg <input>'
00:
00: Please choose (default will boot in 30 seconds): #cp vi vmsg 2

You choose a configuration by specifying the configuration number. For example, to boot configuration boot3 specify

#cp vi vmsg 2

You can also specify additional kernel parameters by appending them to the configuration number. For example, you can specify:

#cp vi vmsg 2 maxcpus=1

These parameters are concatenated to the end of the existing kernel parameters that are used by your boot configuration when booting Linux.