Bug#983486: zipl: allow other packages to provide config snippets
On 27.02.21 05:59, Dimitri John Ledkov wrote:
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> On Thu, 25 Feb 2021, 07:51 Christian Borntraeger, <borntraeger@de.ibm.com <mailto:borntraeger@de.ibm.com>> wrote:
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> On 24.02.21 23:40, dann frazier wrote:
> > Source: s390-tools
> > Version: 2.15.1-2
> >
> > I'm one of the maintainers of kdump-tools, which has a need to manipulate
> > the kernel command line parameters in boot loader configurations.
> > Currently zipl provides no way to do this without modifying
> > /etc/zipl.conf directly. It would be helpful if there was e.g. an
> > /etc/zipl.conf.d/ interface for dropping in additional configuration.
> >
> > As an example, GRUB provides an /etc/default/grub.d/ directory, which
> > allows us to drop in a file like this:
> >
> > $ cat /etc/default/grub.d/kdump-tools.cfg
> > GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT crashkernel=384M-:128M"
> >
> > One idea of how to implement this would be to do something similar to
> > GRUB and ship a tool (say, update-zlib) that generates a static
> > /etc/zlib.conf as directed by a set of shell variables (say
> > /etc/default/zlib). It could then process a directory of snippets (say
> > /etc/default/zlib.d/*) allowing other packages to tweak/override the
> > configuration defined by those variables.
> >
> > I realize that while that this design would have an upgrade problem
> > for existing users, but perhaps we could provide an opt-in-only
> > migration path.
> >
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> Newer zipls also provide a way to specify BLS entries
> https://systemd.io/BOOT_LOADER_SPECIFICATION/ <https://systemd.io/BOOT_LOADER_SPECIFICATION/>
> would that help you?
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> grub.d snippets are typically used to extend kernel cmdline arguments for all entries. Is there variable substitution available?
As Stefan Haberland pointed out, we are currently working on environment support. This is probably good enough for
that use case. Not sure how far this has progressed, though.
As far as I understand it BLS is purely declarative and there is no ability to say "and append this value to all entries", "and append that value to all entries". From locations that have drop-ins from packaged software and/or user.
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> Also in Debian / Ubuntu we only generate two static entries in zipl.conf for the current and last kernel. BSL might be useful for us to list all installed / bootable kernels. But not sure how to reconcile that with arguments in zipl.conf.
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> If something like a zipl.conf.d is still considered valueable, maybe
> open an issue for the
> upstream project https://github.com/ibm-s390-linux/s390-tools/issues <https://github.com/ibm-s390-linux/s390-tools/issues>
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