Adding kernel parameters to a boot configuration

LPAR mode z/VM guest

When booting a Linux® instance, you can specify kernel parameters that are used in addition to the parameters in the boot configuration.

By default, the kernel parameters you specify when booting are concatenated to the end of the kernel parameters in your boot configuration. In total, the combined kernel parameter string that is used for booting can be up to 4096 characters.

If kernel parameters are specified in a combination of methods, they are concatenated in the following order:
  1. Kernel parameters that have been included in the boot configuration with zipl
  2. DASD only: zipl kernel parameters that are specified with the interactive boot menu
  3. Depending on where you are booting Linux:
    • z/VM®: kernel parameters that are specified with the PARM parameter for CCW boot devices; kernel parameters that are specified as SCPDATA for SCSI boot devices
    • LPAR: kernel parameters that are specified on the HMC Load panel for SCSI boot devices

If the combined kernel parameter string contains conflicting settings, the last specification in the string overrides preceding ones. Thus, you can specify a kernel parameter when booting to override an unwanted setting in the boot configuration.

Examples

  • If the kernel parameters in your boot configuration include possible_cpus=8 but you specify possible_cpus=2 when booting, Linux uses possible_cpus=2.
  • If the kernel parameters in your boot configuration include resume=/dev/dasda2 to specify a disk from which to resume the Linux instance when it has been suspended, you can circumvent the resume process by specifying noresume when booting.