On Thu, 6 Aug 2020 17:05:07 +0200 Thomas Huth <[email protected]> wrote:
> Booting on s390x is a little bit different compared to other architectures. > Let's add some information for people who are not yet used to this. > > Signed-off-by: Thomas Huth <[email protected]> > --- > docs/system/s390x/bootdevices.rst | 82 +++++++++++++++++++++++++++++++ > docs/system/target-s390x.rst | 1 + > 2 files changed, 83 insertions(+) > create mode 100644 docs/system/s390x/bootdevices.rst > > diff --git a/docs/system/s390x/bootdevices.rst > b/docs/system/s390x/bootdevices.rst > new file mode 100644 > index 0000000000..68f0ffd450 > --- /dev/null > +++ b/docs/system/s390x/bootdevices.rst > @@ -0,0 +1,82 @@ > +Boot devices on s390x > +===================== > + > +Booting with bootindex parameter > +-------------------------------- > + > +For classical mainframe guests (i.e. LPAR or z/VM installations), you always > +have to exactly specify the disk where you want to boot from (or "IPL" from, s/exactly/explictly/ ? > +in s390x-speak -- IPL means "Initial Program Load"). Especially, there can s/Especially/In particular/ ? > +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 > +informatin for being bootable), it is recommended to specify a ``scsi-cd`` s/informatin for being/information in order to be/ > +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. (...) This looks good to me, and is certainly helpful. I can fix the nits myself and apply it. There's also some documentation regarding DASD IPL in the devel guide; but as that is mostly helpful for people actually working with the code, I don't think that it makes sense to cross-reference it.
