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25.3.4. Configuring a System z Network Device for Network Root File System

To add a network device that is required to access the root file system, you only have to change the boot options. The boot options can be in a parameter file (refer to Chapter 26, Parameter and Configuration Files) or part of a zipl.conf on a DASD or FCP-attached SCSI LUN prepared with the zipl boot loader. There is no need to recreate the initramfs.
Dracut (the mkinitrd successor that provides the functionality in the initramfs that in turn replaces initrd) provides a boot parameter to activate network devices on System z early in the boot process: rd_ZNET=.
As input, this parameter takes a comma-separated list of the NETTYPE (qeth, lcs, ctc), two (lcs, ctc) or three (qeth) device bus IDs, and optional additional parameters consisting of key-value pairs corresponding to network device sysfs attributes. This parameter configures and activates the System z network hardware. The configuration of IP addresses and other network specifics works the same as for other platforms. Refer to the dracut documentation for more details.
cio_ignore for the network channels is handled transparently on boot.
Example boot options for a root file system accessed over the network through NFS:
root= cio_ignore=all,!0.0.0009 rd_ZNET=qeth,0.0.0a00,0.0.0a01,0.0.0a02,layer2=1,portno=0,portname=OSAPORT ip=‑server.subdomain.domain:eth0:none rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us