IBM Support

Break into a shell during installation of Red Hat Linux on Z

How To


Summary

If using a PARM file to install RHEL (Red Hat Enterprise Linux) on IBM Z, under z/VM, you can force it to break into a shell. This is useful if you have to format a disk, for example, before the installer runs.

Environment

Red Hat Enterprise Linux
IBM z/VM

Steps

You can access a shell by rescuing the system instead of installing. That will give you a live environment to run commands against the storage.
You can also use rd.break to drop into a shell at specific points during the boot process.
   rd.break
      drop to a shell at the end
   rd.break={cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup}
      drop to a shell on defined breakpoint
To do this, log on to your z/VM guest, start CMS and use XEDIT to edit your PARM file.
z/VM ONLINE   
                                            

                               / VV         VVV MM      MM                
                              / VV       VVV MMM    MMM                 
                  ZZZZZZ    /  VV     VVV  MMMM  MMMM                  
                     ZZ    /   VV   VVV   MM MM MM MM                   
                    ZZ    /    VV VVV    MM MMM MM                    
                   ZZ    /     VVVVV     MM  M  MM                     
                  ZZ    /      VVV      MM      MM                      
                 ZZZZZZ /       V       MM      MM   

                   built on IBM Virtualization Technology        

Fill in your USERID and PASSWORD and press ENTER         
(Your password will not appear when you type it)    

                      
USERID  ===> RHEL                                                 
PASSWORD ===> *****                                                          

COMMAND ===>


00: z/VM Version 6 Release 4.0, Service Level 1701 (64-bit),
00: built on IBM Virtualization Technology
00: There is no logmsg data
00: FILES: 0007 RDR,  NO PRT,  NO PUN
00: LOGON AT 15:00:00 EDT FRIDAY 07/12/19
z/VM V6.4.0   2018-08-28 17:25


IPL CMS

Ready; T=0.01/0.01 15:00:24
z/VM V6.4.0   2018-08-28 17:25
Edit the parm file and add rd.break
XEDIT REDHAT PARM A1
REDHAT PARM file
ro ramdisk_size=40000 cio_ignore=all,!condev
inst.repo=nfs:1.2.3.4:/iso/RHEL8
rd.dasd=0.0.3568
rd.znet=qeth,0.0.bdf0,0.0.bdf1,0.0.bdf2,layer2=0,portno=0,portname=DUMMY
ip=1.2.3.4::1.2.3.1:255.255.255.0:myrhel:encbdf0:none
nameserver=172.18.0.1 searchdomain ibm.com
Add rd.break to one of the kernel option lines:
ro ramdisk_size=40000 cio_ignore=all,!condev rd.break
inst.repo=nfs:1.2.3.4:/iso/RHEL8
rd.dasd=0.0.3568
rd.znet=qeth,0.0.bdf0,0.0.bdf1,0.0.bdf2,layer2=0,portno=0,portname=DUMMY
ip=1.2.3.4::1.2.3.1:255.255.255.0:myrhel:encbdf0:none
nameserver=172.18.0.1 searchdomain ibm.com
Save and quit the file, then install using your exec file. Before the installation a shell prompt will open up to allow you to format drives, etc.

Document Location

Worldwide

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Document Information

Modified date:
12 August 2021

UID

ibm10959225

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