SCSI IPL parameters

Load type

Without SCSI IPL there are the two load types, normal and clear. Both are used to IPL an operating system. The only difference is that the memory will be cleared before IPL in the second case. SCSI IPL introduces two new load types called SCSI and SCSI dump. The load type SCSI loads an operating system from a SCSI device and clears the memory every time. SCSI dump loads a dump program from a SCSI device. In this case the memory will not be cleared.

Load address

(Required.) The load address is a two-byte hexadecimal number. It is the device number of the FCP device and it is NOT associated with an I/O device, but with the FCP channel! This is one of the most important differences compared to CCW IPL. This is the only SCSI IPL parameter defined in the IODF.

Worldwide port name

(Required.) The worldwide port name (WWPN) is an eight-byte hexadecimal number and uniquely identifies the target port of the SCSI target device.

Logical unit number

(Required.) The logical unit number (LUN) is an eight-byte hexadecimal number that identifies the logical unit representing the IPL device.

Boot program selector

(Optional.) Selects a boot configuration, which can be a Linux kernel, a kernel parameter file, or optionally a ram disk. There could be up to 31 (decimal 0 – 30) different configurations on a single SCSI disk, independent of on which partition they are stored. The different configurations must be prepared with the Linux zipl tool. The default value is 0.

There are several possible uses for this parameter. For example, if you have one production and one development kernel, it allows you to always IPL the system even if the development kernel does not work. Another use would be a rescue system, or the same kernel with several different kernel parameters or ram disks. This parameter adds flexibility to SCSI IPL.

Boot record logical block address

(Optional.) The boot record logical block address specifies the entry or anchor point to find the operating system on a SCSI disk. A block number can be specified here. Usually, in Linux, this block is the master boot record and the first block on the IPL device. With this parameter it is possible to use a different block as entry point. For example, z/VM® does not have a master boot record. The default value is 0.

Operating system specific load parameters

(Optional.) Operating system specific load parameters are parameters for the loaded operating system. It is intended to hand over parameters to the operating system or dump program. This field is only passed through. The main difference to all other SCSI IPL parameters is that this field is not used to access the IPL device or the operating system on the IPL device. This field is currently restricted to 256 Bytes (SE) and 4096 Bytes (z/VM).

For booting Linux, use this field to specify kernel parameters. During the boot process, these parameters are concatenated to the end of the existing kernel parameters that are used by your boot configuration. The specifications must contain ASCII characters only. If characters other than ASCII are present, the content of the field is ignored during IPL.

If you specify the kernel parameters with a leading equal sign (=), the existing kernel parameters are ignored and replaced with the kernel parameters in this field. If you replace the existing kernel parameters, be sure not to omit any kernel parameters required by your boot configuration.

For dump tools, use this field to specify additional dump tool parameters. Other than with kernel parameters, you cannot replace the existing dump tool parameters.

Load parameter

This parameter is SCSI IPL independent and can be used as usual. The loaded operating system receives these IPL parameters at a later point in time. This parameter is not used to access the IPL device.

The following parameters are not needed for SCSI IPL, but are mentioned for completeness:

Store status and time-out value

These two parameters are not needed for SCSI IPL. For SCSI IPL, no store status is required and for SCSI dump a store status command is always performed.