Re: Odd problem with submenus

[John Haxby <john.haxby@oracle.com>]

On 02/07/14 18:07, Andrey Borzenkov wrote:
> В Tue, 01 Jul 2014 17:59:35 +0100
> John Haxby <john.haxby@oracle.com> пишет:
> 
>> > Hello,
>> > 
>> > I have a warning generated by grub2-mkconfig that shows up on various
>> > systems that I'm not sure what to do about.  Well, I know I can ignore
>> > it, but I'm not sure what do do about not getting the warning in the
>> > first place.
>> > 
>> > On this machine here, I have
>> > 
>> > menuentry 'Fedora, with Linux 3.14.9-200.fc20.x86_64' --class ...
>> > 
>> > and grub2-set-default 'Fedora, with ...' is OK, but then
>> > 
>> > and I also have GRUB_DISABLE_SUBMENU=true i /etc/default/grub, so
>> > 
>> > $ grub2-mkconfig -o /boot/grub2/grub.cfg
>> > ...
>> > Warning: Please don't use old title `Fedora, with Linux
>> > 3.14.9-200.fc20.x86_64' for GRUB_DEFAULT, use `Advanced options for
>> > Fedora>Fedora, with Linux 3.14.9-200.fc20.x86_64' (for versions before
>> > 2.00) or
>> > `gnulinux-advanced-d87b5f54-5bfb-45bd-b300-f4b1db6d5dfb>gnulinux-3.14.9-200.fc20.x86_64-advanced-d87b5f54-5bfb-45bd-b300-f4b1db6d5dfb'
>> > (for 2.00 or later)
>> > 
>> > Exhorting me to use a submenu default when there are no submenus is
>> > clearly wrong, so in /etc/grub.d/10_linux (and the other
>> > platform-specific files) there's:
>> > 
>>> > >       if [ x"$title" = x"$GRUB_ACTUAL_DEFAULT" ] || [ x"Previous Linux versions>$title" = x"$GRUB_ACTUAL_DEFAULT" ]; then
>>> > >           replacement_title="$(echo "Advanced options for ${OS}" | sed 's,>,>>,g')>$(echo "$title" | sed 's,>,>>,g')"
>>> > >           quoted="$(echo "$GRUB_ACTUAL_DEFAULT" | grub_quote)"
>>> > >           title_correction_code="${title_correction_code}if [ \"x\$default\" = '$quoted' ]; then default='$(echo "$replacement_title" | grub_quote)'; fi;"
>>> > >           grub_warn "$(gettext_printf "Please don't use old title \`%s' for GRUB_DEFAULT, use \`%s' (for versions before 2.00) or \`%s' (for 2.00 or later)" "$GRUB_ACTUAL_DEFAULT" "$replacement_title" "gnulinux-advanced-$boot_device_id>gnulinux-$version-$type-$boot_device_id")"
>>> > >       fi
>> > 
>> > It's easy enough to add a test for GRUB_DISABLE_SUBMENU here but I'm at
>> > a loss to know why this clause is needed at all.  I know it means that
>> > if I have submenus enabled then I can just set the default to be the
>> > title of a submenu and not worry about the "Advanced options ..." bit,
>> > but it looks to me as though it was just a transition thing which is
>> > really no longer needed.
>> > 
> You never know it; there is no reason to break working configuration.
> 
>> > Is this really no longer needed or am I missing something?  I'm happy to
>> > submit a patch either way.
>> > 
> 
> Yes, please, make it conditionally add submenu title to
> replacement_title based on GRUB_DISABLE_SUBMENU. Please also fix all
> scripts (the bug is not limited to linux).

Happy to oblige.

Actually, there are two problems.  The various GRUB_DISABLE_* options
all check for "true" with the exception of GRUB_DISABLE_SUBMENU which
checks for "y".   This is likely to cause some confusion, not least
because Fedora and RHEL7 are both using "true".  I'll work on two
patches ...

My long-time preferred solution for things like this[1], though is to
define functions like this:

    case x"$DISABLE_GRUB_SUBMENU" in
       xy*|xtrue|x1)  disable_grub_submenu () { return 0; } ;;
       *) disable_grub_submenu () { return 1; } ;;
    esac

And then I can do

   if disable_grub_submenu; then ...

which I think is easier to read and gets all of the confusion about what
constitutes truth into a single place.

jch


[1] since before bash, probably