[CentOS] C8.1 Grub problem

Wed Apr 8 11:40:24 UTC 2020
Jonathan Billings <billings at negate.org>

On Apr 8, 2020, at 04:01, Alessandro Baggi <alessandro.baggi at gmail.com> wrote:
> Il 08/04/20 01:46, Jonathan Billings ha scritto:
>> grubby only alters the existing configuration.  It never regenerates the grub.cfg in EFI.
>> You can’t use “grub2-mkconfig” to create individual boot spec entries.
>> --
>> Jonathan Billings <billings at negate.org>
> Please explain how the process work, it is not so clear for me. I'm confused.
> In C7 when I need to modify grub menu kernel option I modify /etc/default/grub and run grub2-mkconfig and thats all. It always worked for me.
> On C8 this does not work anymore, grub2-mkconfig is not enough, it generates only the grub.cfg but it does not update the menu entries and need to modify each entry using grubby. At this point what grub.cfg is used for if directives are not loaded by it and need grubby to modify entries?
> I'm missing something....

Don’t use grub2-mkconfig, it is really only for initial grub configuration. It has a problematic past in CentOS 7 too. Disabling blscfg is possible but it isn’t the default setup and not the recommended way of updating kernel entries. 

If you need to update kernel parameters, use grubby. That’s what is run in the kernel package install scripts (via new-kernel-package). That’s what is run in packages like the nvidia 3rd party packages. 

Jonathan Billings