Kernel parameters

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6.18 z/VM guest

If the DCSS block device support has been compiled into the kernel, you configure the device driver by adding parameters to the kernel parameter line.

Use the dcssblk.segments kernel parameter to load one or more DCSSs during the boot process (for example, for use as swap devices).

Figure 1. DCSS kernel parameter syntax

1 dcssblk.segments= + , + : <dcss>? (local)
<dcss>
specifies the name of a DCSS as defined on the z/VM® hypervisor. The specification for <dcss> is converted from ASCII to uppercase EBCDIC.
:
the colon (:) separates DCSSs within a set of DCSSs to be mapped to a single DCSS device. You can map a set of DCSSs to a single DCSS device if the DCSSs in the set form a contiguous memory space.

You can specify the DCSSs in any order. The name of the first DCSS you specify is used to represent the device under /sys/devices/dcssblk.

(local)
sets the access mode to exclusive-writable after the DCSS or set of DCSSs are loaded.
,
the comma (,) separates DCSS devices.

Examples

The following parameter in the kernel parameter line loads three DCSSs during the boot process: DCSS1, DCSS2, and DCSS3. DCSS2 is accessed in exclusive-writable mode and can be included in /etc/fstab and used as a swap device. 
dcssblk.segments="dcss1,dcss2(local),dcss3"
The following parameter in the kernel parameter line loads four DCSSs during the boot process: DCSS4, DCSS5, DCSS6, and DCSS7. The device driver creates two DCSS devices. One device maps to DCSS4. The other device maps to the combined storage space of DCSS5, DCSS6, and DCSS7 as a single device. 
dcssblk.segments="dcss4,dcss5:dcss6:dcss7"