# S/390 Limitations

In order to run the installation system a working network setup and ssh session is needed on S/390.

The booting process starts with a network setup that prompts you for several network parameters. If the setup is successful, you will login to the system by starting an ssh session which will launch the standard installation system.

## S/390 Boot Parameters

On S/390 you can append boot parameters in the parm file. This file can either be in ASCII or EBCDIC format. It needs to be fixed-width with 80 characters per line. A sample parm file `parmfile.debian` is provided with the installation images. If a parameter is too long to fit into the 80 characters limit it can simply be continued in the first column of the next line. All the lines are concatenated without spaces when being passed to the kernel.

If you boot the installer in a logical partition (LPAR) or virtual machine (VM) where a lot of devices are visible, you can instruct the kernel to restrict the list to a fixed set of devices. This is advised for the installer's boot process if a lot of disks are visible, most likely in LPAR mode. The cio_ignore option supports both a blacklist (to only disallow a few devices) and a whitelist (to only allow specific devices):

     # blacklist: just ignore the two devices 300 and 301
     cio_ignore=0.0.0300-0.0.0301
     # whitelist: ignore everything but 1150, FD00, FD01 and FD02
     cio_ignore=all,!0.0.1150,!0.0.fd00-0.0.fd02

Please note that all devices numbers' hex digits need to be specified in lower case. Furthermore if this boot parameter is used all devices need to be listed: this includes at least disks, network devices and the console. To be considered during the installer's boot process the above option needs to be added to `parmfile.debian`.