mirror of
https://github.com/xemu-project/xemu.git
synced 2024-11-24 03:59:52 +00:00
7a21bee2aa
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20220707163720.1421716-5-berrange@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Thomas Huth <thuth@redhat.com>
83 lines
3.9 KiB
ReStructuredText
83 lines
3.9 KiB
ReStructuredText
Boot devices on s390x
|
|
=====================
|
|
|
|
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).
|
|
|
|
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
|
|
example::
|
|
|
|
qemu-system-s390x -drive if=none,id=dr1,file=guest.qcow2 \
|
|
-device virtio-blk,drive=dr1,bootindex=1
|
|
|
|
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::
|
|
|
|
qemu-system-s390x -blockdev file,node-name=c1,filename=... \
|
|
-device virtio-scsi \
|
|
-device scsi-cd,drive=c1,bootindex=1
|
|
|
|
Note that you really have to use the ``bootindex`` property to select the
|
|
boot device. The old-fashioned ``-boot order=...`` command of QEMU (and
|
|
also ``-boot once=...``) is not supported on s390x.
|
|
|
|
|
|
Booting without bootindex parameter
|
|
-----------------------------------
|
|
|
|
The QEMU guest firmware (the so-called s390-ccw bios) has also some rudimentary
|
|
support for scanning through the available block devices. So in case you did
|
|
not specify a boot device with the ``bootindex`` property, there is still a
|
|
chance that it finds a bootable device on its own and starts a guest operating
|
|
system from it. However, this scanning algorithm is still very rough and may
|
|
be incomplete, so that it might fail to detect a bootable device in many cases.
|
|
It is really recommended to always specify the boot device with the
|
|
``bootindex`` property instead.
|
|
|
|
This also means that you should avoid the classical short-cut commands like
|
|
``-hda``, ``-cdrom`` or ``-drive if=virtio``, since it is not possible to
|
|
specify the ``bootindex`` with these commands. Note that the convenience
|
|
``-cdrom`` option even does not give you a real (virtio-scsi) CD-ROM device on
|
|
s390x. Due to technical limitations in the QEMU code base, you will get a
|
|
virtio-blk device with this parameter instead, which might not be the right
|
|
device type for installing a Linux distribution via ISO image. It is
|
|
recommended to specify a CD-ROM device via ``-device scsi-cd`` (as mentioned
|
|
above) instead.
|
|
|
|
|
|
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::
|
|
|
|
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
|
|
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.
|
|
The supported configuration file entries are ``DEFAULT``, ``LABEL``,
|
|
``KERNEL``, ``INITRD`` and ``APPEND`` (see the `Syslinux Config file syntax
|
|
<https://wiki.syslinux.org/wiki/index.php?title=Config>`__ for more
|
|
information).
|