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
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 <thuth@redhat.com>
---
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,
+in s390x-speak -- IPL means "Initial Program Load"). Especially, 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
+informatin for being 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 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).
diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst
index 644e404ef9..c636f64113 100644
--- a/docs/system/target-s390x.rst
+++ b/docs/system/target-s390x.rst
@@ -31,4 +31,5 @@ Architectural features
======================
.. toctree::
+ s390x/bootdevices
s390x/protvirt
--
2.18.1
On Thu, 6 Aug 2020 17:05:07 +0200 Thomas Huth <thuth@redhat.com> 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 <thuth@redhat.com> > --- > 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.
On 8/10/20 12:18 PM, Cornelia Huck wrote: > On Thu, 6 Aug 2020 17:05:07 +0200 > Thomas Huth <thuth@redhat.com> 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 <thuth@redhat.com> >> --- >> 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/ ? Or "to explicit the disk ..."? > >> +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. > >
On Mon, 10 Aug 2020 12:20:53 +0200 Philippe Mathieu-Daudé <philmd@redhat.com> wrote: > On 8/10/20 12:18 PM, Cornelia Huck wrote: > > On Thu, 6 Aug 2020 17:05:07 +0200 > > Thomas Huth <thuth@redhat.com> 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 <thuth@redhat.com> > >> --- > >> 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/ ? > > Or "to explicit the disk ..."? Hm, not sure what that means?
On 8/10/20 12:29 PM, Cornelia Huck wrote: > On Mon, 10 Aug 2020 12:20:53 +0200 > Philippe Mathieu-Daudé <philmd@redhat.com> wrote: > >> On 8/10/20 12:18 PM, Cornelia Huck wrote: >>> On Thu, 6 Aug 2020 17:05:07 +0200 >>> Thomas Huth <thuth@redhat.com> 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 <thuth@redhat.com> >>>> --- >>>> 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/ ? >> >> Or "to explicit the disk ..."? > > Hm, not sure what that means? Sorry I thought it was a verb, but the verb is explicitize. "to explicitly specify" sounds good (typo fixed).
On Thu, 6 Aug 2020 17:05:07 +0200 Thomas Huth <thuth@redhat.com> 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 <thuth@redhat.com> > --- > 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 Thanks, queued with wording nits fixed.
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