Re: [PATCH for-5.2 0/6] Continue booting in case the first device is not bootable

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 28 Jul 2020 20:37:28 +0200
Thomas Huth <thuth@redhat.com> wrote:

> If the user did not specify a "bootindex" property, the s390-ccw bios
> tries to find a bootable device on its own. Unfortunately, it alwasy
> stops at the very first device that it can find, no matter whether it's
> bootable or not. That causes some weird behavior, for example while
> 
>  qemu-system-s390x -hda bootable.qcow2
> 
> boots perfectly fine, the bios refuses to work if you just specify
> a virtio-scsi controller in front of it:
> 
>  qemu-system-s390x -device virtio-scsi -hda bootable.qcow2
> 
> Since this is quite uncomfortable and confusing for the users, and
> all major firmwares on other architectures correctly boot in such
> cases, too, let's also try to teach the s390-ccw bios how to boot
> in such cases.

I think this makes sense: If you IPL an LPAR or a z/VM guest, you are
always required to explicitly specify a device to load from (at least
as far as I remember). For QEMU, we have decided to allow starting
without an explicitly specified boot device as well, so we have already
deviated from the other s390 procedures. Let's just make that case
behave the same as everywhere else.

> 
> For this, we have to get rid of the various panic()s and IPL_assert()
> statements at the "low-level" function and let the main code handle
> the decision instead whether a boot from a device should fail or not,
> so that the main code can continue searching in case it wants to.
> 
>  Thomas
> 
> Thomas Huth (6):
>   pc-bios/s390-ccw/Makefile: Compile with -std=gnu99, -fwrapv and
>     -fno-common
>   pc-bios/s390-ccw: Move ipl-related code from main() into a separate
>     function
>   pc-bios/s390-ccw: Move the inner logic of find_subch() to a separate
>     function
>   pc-bios/s390-ccw: Do not bail out early if not finding a SCSI disk
>   pc-bios/s390-ccw: Scan through all boot devices if none has been
>     specified
>   pc-bios/s390-ccw: Allow booting in case the first virtio-blk disk is
>     bad
> 
>  pc-bios/s390-ccw/Makefile        |   7 +-
>  pc-bios/s390-ccw/bootmap.c       |  34 ++++--
>  pc-bios/s390-ccw/main.c          | 172 +++++++++++++++++++------------
>  pc-bios/s390-ccw/s390-ccw.h      |   2 +-
>  pc-bios/s390-ccw/virtio-blkdev.c |   7 +-
>  pc-bios/s390-ccw/virtio-scsi.c   |  25 +++--
>  pc-bios/s390-ccw/virtio-scsi.h   |   2 +-
>  7 files changed, 157 insertions(+), 92 deletions(-)
>