Booting from the z/VM reader

Red Hat Enterprise Linux 9.2 z/VM guest

Boot Linux® by issuing the IPL command with the z/VM reader as the IPL device. You first must transfer the boot data to the reader.

Before you begin

You need the following files, all in record format fixed 80:

Linux kernel image with built-in z/VM reader boot loader code. This is the case for the default Red Hat® Enterprise Linux 9.2 kernel.
Kernel parameters (optional)
Initial RAM disk image (optional)

About this task

This information is a summary of how to boot Linux from a z/VM reader. For more details, refer to Redpaper Building Linux Systems under IBM® VM, REDP-0120.

Procedure

Proceed like this to boot Linux from a z/VM reader:

Establish a CMS session with the guest where you want to boot Linux.
Transfer the kernel image, kernel parameters, and the initial RAM disk image to your guest.
You can obtain the files from a shared minidisk or use:
- The z/VM sendfile facility.
- An FTP file transfer in binary mode.
Files that are sent to your reader contain a file header that you must remove before you can use them for booting. Receive files that you obtain through your z/VM reader to a minidisk.
Set up the reader as a boot device.
1. Ensure that your reader is empty.
2. Direct the output of the punch device to the reader. Issue:
```
spool pun * rdr
```
3. Use the CMS PUNCH command to transfer each of the required files to the reader.
  Be sure to use the no header option to omit the file headers.
  - First transfer the kernel image.
  - Second transfer the kernel parameters.
  - Third transfer the initial RAM disk image, if present.
  For each file, issue a command of this form:
```
pun <file_name> <file_type> <file_mode> (noh
```
4. Optional: Ensure that the contents of the reader remain fixed.
```
change rdr all keep nohold
```
  If you omit this step, all files are deleted from the reader during the IPL that follows.
Issue the IPL command:
```
ipl 000c clear parm <kernel_parameters>
```
where:

0x000c

is the device number of the reader.

parm <kernel_parameters>

is an optional 64-byte string of kernel parameters to be concatenated to the end of the existing kernel parameters that are used by your boot configuration.