Re: [RFC QEMU PATCH] pc-bios/s390-ccw: Add zipl-like "BOOT_IMAGE=x" to the kernel parameters

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 16 Dec 2019 12:29:24 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 16.12.19 12:24, Thomas Huth wrote:
> >  Note: I've marked the patch as RFC since I'm not quite sure whether
> >  this is really the right way to address this issue: It's unfortunate
> >  that we have to mess with different location in ZIPL which might also
> >  change again in the future. As suggested by Christian on IRC last week,
> >  maybe it would make more sense to change ZIPL to add this parameter
> >  already when zipl is installed (i.e. by the Linux userspace "zipl" pro-
> >  gram), instead of adding it during boot time? Also, the BOOT_IMAGE para-
> >  meter on s390x is quite different from the BOOT_IMAGE paramter that is
> >  used on x86 - while s390x only uses one single number here, the x86
> >  variant (added by grub2, I guess) uses the boot device + full filename
> >  of the kernel on the boot partition. Should we maybe make the s390x
> >  variant more conform to x86? If so, I think this really has to be fixed
> >  in zipl userspace tool, and not in the s390-ccw bios (and zipl stage3
> >  bootloader).  
> 
> Yes, I actually think we should revisit the whole BOOT_IMAGE scheme on s390.
> Maybe we should use the kernel name, or the name of the boot menu entry.
> And maybe we should not use 0 (when the default is running) but instead
> really use to what 0 points to.

Probably dumb question: Is booting via the s390-ccw bios the only time
we boot without going through zipl? What about e.g. booting from the
reader under z/VM? There's probably no BOOT_IMAGE= statement there,
either?