Bug#853855: di-utils: Kernel boot options containing a dot are not propagated to the installed system

[Ian Campbell <ijc@debian.org>]

On Wed, 2017-02-01 at 15:30 +0100, Emmanuel Kasper wrote:
> Package: di-utils
> Version: 1.117
> Severity: minor
> Tags: d-i
> 
> A kernel boot param like net.ifnames=0 will be skipped when the
> installer parses the boot option for setting the bootloader.
> 
> Found in di-utils: 
> 
>                 # Skip module-specific variables
>                 varnodot="${var##*.*}"
>                 if [ "$varnodot" = "" ]; then
>                         continue
>                 fi
> 
> So basically any option containing a dot is not propagated to the
> installed system.  This was introduced by
> 7cf15980d714da8b958a73c93459ee09fdbb9415 ("Skip new module-specific
> parameters in user-params.")
> 
> I found no documented or obvious reason for this behaviour.

Sounds like the assumption was that any "foo.bar=baz" arguments were
always to be used as the "bar=baz" option when loading the "foo" module
(i.e. "modprobe foo bar=baz"), which I think the installer supports
(for convenience) but perhaps not the installed system (where they
should instead be in /etc/modules or /etc/modprobe.conf or similar)
does not?

Of course this logic falls apart in the presence of "foo" (such as
"net") which are not modules but instead are subsystems.

Ian.