Ubuntu
subiquity package

  1. Bug #2009141
  2. Comment #48

Comment 48 for bug 2009141

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2023-04-20 09:12 EDT-------
(In reply to comment #47)
> At '<email address hidden>' - nah, that's not what I'm saying, things are
> (historically) a bit more complex:
>
> So there is '--' vs '---', whereas Kernel uses everything until '--' and
> userspace uses everything.
>
> Back in the early Debian-Installer days, d-i used '--' to separate things
> (for use in installed & installer system vs use in the installer only). When
> systemd & kernel had a spat, and kernel started to use '--' separator,
> Debian was forced to change to something else and started to use '---'. So
> both '--' and '---' have their use case today.
> Notice this example:
> debug -- systemd.log_level=info --- systems.log_level=debug
> Which will have all three on for installer system, propagate the first two
> to the installed system, with kernel itself only considering the first
> option.
> Because of historical usage of '--' and the conflict that Debian had to
> yield '--' to kernel.
> Depending on the age of the docs one may find in the documentation, info
> might be outdated or wrong, hence confusing.
>
> Some more references:
>
> https://docs.kernel.org/admin-guide/kernel-parameters.html

yes, I had referenced that earlier

> https://d-i.debian.org/manual/en.s390x/install.en.pdf
> A ?---? in the boot options has special meaning. Kernel parameters that
> appear after the last ?---? may be copied
> into the bootloader configuration for the installed system (if supported by
> the installer for the bootloader).
> The installer will automatically filter out any options (like
> preconfiguration options) that it recognizes.

Ah, I wasn't aware of that. Very insightful. Thanks, Frank.

Since the kernel has '--' and recently also started to complain about unkown parameters if user space stuff appears before the '--', I was just wondering how the kernel would parse and interpret the triple-dash '---' and if the kernel could trip over the triple-dash and maybe that could cause the weird special character /proc/cmdline we saw.