Re: RFC: Support Linux command line variants in grub-mkconfig

[Martin Orr]

On Tue 19 Jan 22:26:51 2010, Robert Millan wrote:

> On Mon, Jan 18, 2010 at 09:03:53PM +0000, Martin Orr wrote:
> > I would like to be able to choose between alternative Linux command
> > lines in my GRUB menu (specifically, I want a "selinux=0" option, but I
> > can imagine that people might want other things).  I could add an extra
> > script to /etc/grub.d to do this, but then I have to copy the logic in
> > 10_linux to detect what kernel versions are available, and they do not
> > appear in the correct place in the menu.  It would be simpler if you
> > could specify variant command lines in /etc/default/grub and have them
> > handled automatically in 10_linux.
> >
> > The attached patch allows (for example) the following configuration in
> > /etc/default/grub:
> > GRUB_LINUX_VARIANTS="noselinux kms"
> >
> > GRUB_CMDLINE_LINUX_noselinux="selinux=0"
> > GRUB_LABEL_LINUX_noselinux="SELinux disabled"
> >
> > GRUB_CMDLINE_LINUX_kms="i915.modesetting=1"
> > GRUB_LABEL_LINUX_kms="KMS enabled"
> >
> > This patch is only intended as a demonstration: various details of the
> > implementation still need to be sorted out, such as
> > internationalization.  Suggestions of wildly different
> > approaches/configuration interfaces are welcome.
>
> I think this is growing severely overengineered.  It is already more
> complex than it needs to be.
>
> The scripts in /etc/grub.d *are* config files.  There's no reason you
> can't edit them to suit your needs.

I agree that my solution does seem rather overengineered.

My problem is that while /etc/grub.d/* may be config files in some 
technical sense, they don't behave like them.  In particular for most 
config files, changes you make are largely "orthogonal" to the rest of 
the file whereas my changes to /etc/grub.d are mixed in with complex 
logic which I have no interest in changing.  Combined with frequent 
changes to the default version of the file, this makes merging new 
versions a burden.

My patch reduces the configuration needed to set up variant command 
lines to a few lines  in /etc/default/grub, which are indeed orthogonal 
to the rest of the file.

To specify more precisely what I dislike about just editing 10_linux, 
the change that I would want to make (and I would guess that this is 
the change people would most often want to make) is to add an extra 
call to linux_entry.  But linux_entry is an "internal" interface which 
could change its arguments in arbitrary ways, and it doesn't even 
provide the features I need (specifically a label argument, added to 
the title of the menu entry) so I end up having to patch linux_entry 
itself as well as adding a new call, and keep these matching whenever 
the default linux_entry changes.

Best wishes,

--
Martin Orr