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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/s390x/bootdevices.rst | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/docs/system/s390x/bootdevices.rst b/docs/system/s390x/bootdevices.rst index b5950133e8..1a7a18b43b 100644 --- a/docs/system/s390x/bootdevices.rst +++ b/docs/system/s390x/bootdevices.rst @@ -53,6 +53,32 @@ recommended to specify a CD-ROM device via ``-device scsi-cd`` (as mentioned above) instead. +Selecting kernels with the ``loadparm`` property +------------------------------------------------ + +The ``s390-ccw-virtio`` machine supports the so-called ``loadparm`` parameter +which can be used to select the kernel on the disk of the guest that the +s390-ccw bios should boot. When starting QEMU, it can be specified like this:: + + qemu-system-s390x -machine s390-ccw-virtio,loadparm=<string> + +The first way to use this parameter is to use the word ``PROMPT`` as the +``<string>`` here. In that case the s390-ccw bios will show a list of +installed kernels on the disk of the guest and ask the user to enter a number +to chose which kernel should be booted -- similar to what can be achieved by +specifying the ``-boot menu=on`` option when starting QEMU. Note that the menu +list will only show the names of the installed kernels when using a DASD-like +disk image with 4k byte sectors. On normal SCSI-style disks with 512-byte +sectors, there is not enough space for the zipl loader on the disk to store +the kernel names, so you only get a list without names here. + +The second way to use this parameter is to use a number in the range from 0 +to 31. The numbers that can be used here correspond to the numbers that are +shown when using the ``PROMPT`` option, and the s390-ccw bios will then try +to automatically boot the kernel that is associated with the given number. +Note that ``0`` can be used to boot the default entry. + + Booting from a network device ----------------------------- |