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Diffstat (limited to 'docs/system/s390x/bootdevices.rst')
| -rw-r--r-- | docs/system/s390x/bootdevices.rst | 53 |
1 files changed, 36 insertions, 17 deletions
diff --git a/docs/system/s390x/bootdevices.rst b/docs/system/s390x/bootdevices.rst index 1a7a18b..97b3914 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:: @@ -76,29 +79,45 @@ 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. +Note that ``0`` can be used to boot the default entry. If the machine +``loadparm`` is not assigned a value, then the default entry is used. + +By default, the machine ``loadparm`` applies to all boot devices. If multiple +devices are assigned a ``bootindex`` and the ``loadparm`` is to be different +between them, an independent ``loadparm`` may be assigned on a per-device basis. + +An example guest using per-device ``loadparm``:: + + qemu-system-s390x -drive if=none,id=dr1,file=primary.qcow2 \ + -device virtio-blk,drive=dr1,bootindex=1 \ + -drive if=none,id=dr2,file=secondary.qcow2 \ + -device virtio-blk,drive=dr2,bootindex=2,loadparm=3 + +In this case, the primary boot device will attempt to IPL using the default +entry (because no ``loadparm`` is specified for this device or for the +machine). If that device fails to boot, the secondary device will attempt to +IPL using entry number 3. + +If a ``loadparm`` is specified on both the machine and a device, the per-device +value will superseded the machine value. Per-device ``loadparm`` values are +only used for devices with an assigned ``bootindex``. The machine ``loadparm`` +is used when attempting to boot without a ``bootindex``. Booting from a network device ----------------------------- -Beside the normal guest firmware (which is loaded from the file ``s390-ccw.img`` -in the data directory of QEMU, or via the ``-bios`` option), QEMU ships with -a small TFTP network bootloader firmware for virtio-net-ccw devices, too. This -firmware is loaded from a file called ``s390-netboot.img`` in the QEMU data -directory. In case you want to load it from a different filename instead, -you can specify it via the ``-global s390-ipl.netboot_fw=filename`` -command line option. - -The ``bootindex`` property is especially important for booting via the network. -If you don't specify the ``bootindex`` property here, the network bootloader -firmware code won't get loaded into the guest memory so that the network boot -will fail. For a successful network boot, try something like this:: +The firmware that ships with QEMU includes a small TFTP network bootloader +for virtio-net-ccw devices. The ``bootindex`` property is especially +important for booting via the network. If you don't specify the ``bootindex`` +property here, the network bootloader won't be taken into consideration and +the network boot will fail. For a successful network boot, try something +like this:: qemu-system-s390x -netdev user,id=n1,tftp=...,bootfile=... \ -device virtio-net-ccw,netdev=n1,bootindex=1 -The network bootloader firmware also has basic support for pxelinux.cfg-style +The network bootloader also has basic support for pxelinux.cfg-style configuration files. See the `PXELINUX Configuration page <https://wiki.syslinux.org/wiki/index.php?title=PXELINUX#Configuration>`__ for details how to set up the configuration file on your TFTP server. |