diff options
| author | Jared Rossi <jrossi@linux.ibm.com> | 2024-10-19 21:29:52 -0400 |
|---|---|---|
| committer | Thomas Huth <thuth@redhat.com> | 2024-10-23 06:53:44 +0200 |
| commit | 0bd107138ff0b171e3cd314dbc200950bcab2b05 (patch) | |
| tree | b603d660921e46a16c2eb679d7135a0d0ca30ca0 /docs | |
| parent | f697bed22f58eff9b2893ac2fe3d511847398400 (diff) | |
docs/system: Update documentation for s390x IPL
Update docs to show that s390x PC BIOS can support more than one boot device.
Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20241020012953.1380075-19-jrossi@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/system/bootindex.rst | 7 | ||||
| -rw-r--r-- | docs/system/s390x/bootdevices.rst | 9 |
2 files changed, 10 insertions, 6 deletions
diff --git a/docs/system/bootindex.rst b/docs/system/bootindex.rst index 8b057f812f..988f7b3beb 100644 --- a/docs/system/bootindex.rst +++ b/docs/system/bootindex.rst @@ -49,10 +49,11 @@ Limitations ----------- Some firmware has limitations on which devices can be considered for -booting. For instance, the PC BIOS boot specification allows only one -disk to be bootable. If boot from disk fails for some reason, the BIOS +booting. For instance, the x86 PC BIOS boot specification allows only one +disk to be bootable. If boot from disk fails for some reason, the x86 BIOS won't retry booting from other disk. It can still try to boot from -floppy or net, though. +floppy or net, though. In the case of s390x BIOS, the BIOS will try up to +8 total devices, any number of which may be disks. Sometimes, firmware cannot map the device path QEMU wants firmware to boot from to a boot method. It doesn't happen for devices the firmware diff --git a/docs/system/s390x/bootdevices.rst b/docs/system/s390x/bootdevices.rst index c97efb8fc0..1a1a764c1c 100644 --- a/docs/system/s390x/bootdevices.rst +++ b/docs/system/s390x/bootdevices.rst @@ -6,9 +6,7 @@ Booting with bootindex parameter For classical mainframe guests (i.e. LPAR or z/VM installations), you always have to explicitly specify the disk where you want to boot from (or "IPL" from, -in s390x-speak -- IPL means "Initial Program Load"). In particular, there can -also be only one boot device according to the architecture specification, thus -specifying multiple boot devices is not possible (yet). +in s390x-speak -- IPL means "Initial Program Load"). So for booting an s390x guest in QEMU, you should always mark the device where you want to boot from with the ``bootindex`` property, for @@ -17,6 +15,11 @@ example:: qemu-system-s390x -drive if=none,id=dr1,file=guest.qcow2 \ -device virtio-blk,drive=dr1,bootindex=1 +Multiple devices may have a bootindex. The lowest bootindex is assigned to the +device to IPL first. If the IPL fails for the first, the device with the second +lowest bootindex will be tried and so on until IPL is successful or there are no +remaining boot devices to try. + For booting from a CD-ROM ISO image (which needs to include El-Torito boot information in order to be bootable), it is recommended to specify a ``scsi-cd`` device, for example like this:: |