update grub2

[Chris Murphy]

On May 18, 2014, at 4:08 PM, Stephen Morris <samorris at netspace.net.au> wrote:

> On 05/18/2014 11:57 PM, Michael Schwendt wrote:
>> On Sun, 18 May 2014 14:57:14 +0200, Patrick Dupre wrote:
>> 
>>> Hello,
>>> 
>>> After an update of teh kernel. the file:
>>> /boot/grub2/grub.cfg is updated.
>>> However thsi file is not update properly.
>> How? In which way is it not updated "properly"?
>> 
>> Prior to installing a new kernel, you could save a copy of grub.cfg,
>> install a new kernel package, and then run diff on the old and new
>> grub.cfg. What do you get?
>> 
>>> If I run:
>>>  grub2-mkconfig -o /boot/grub2/grub.cfg
>>> then the file is OK.
>> Define "OK".
>> 
>> grub2-mkconfig rewrites grub.cfg from scratch and under consideration
>> of template files, such as those in /etc/grub.d, and add-on tools such
>> as os-prober.
>> 
>> On the contrary, grubby (as run via the kernel packages) only inserts
>> a new boot entry into the existing file. It does not recreate the file
>> completely.
> Hi Michael,
>    My experience with grubby being run after kernel installs, when I have been able to get it to run, is that it does recreate the entire grub.cfg file. For example, I have been in the situation where the boot menu had an entry for the latest kernel followed by an group entry for 'Advanced Fedora Options' (or something similar) along with the same structure for Ubuntu, then after running grubby, the groupings were removed and all the entries that were listed in the groups were moved to the top level.

It definitely doesn't recreate the entire file. It does have the ability to add and remove certain entries, and I've experienced the same thing you've described, but it's not easy to reproduce the conditions.

The solution employed on Fedora a while ago was disabling grub submenus by default. I think it's an amusing workaround because ostensibly the idea of grubby is to avoid throwing away data in the grub.cfg that represents the current bootable states of a system, and yet here's an example where it does exactly that.


Chris Murphy