Problem recreating grub2 menu in SL7 dual boot with Win10

[R P Herrold]

On Wed, 24 Jan 2018, Bill Maidment wrote:

> It appears that I need to do yum install grub2-efi-modules (why wasn't this 
> done before? I ask).

Packages are partitioned into a main and sub-packages, so that 
the bloat of un-needed matter is avoided.  UEFI is relatively 
new, and until Windows 10, not really mandated by Microsoft 
installations.  Also the needed hardware (a TPM chip) was not 
universally present, and so that sub-package would seem to be 
bloat to most people

As to how to get a copy, using an second machine to retrieve 
the needed package, and placing it on a data stick comes to  
mind.  If no second machine is at hand, booting into Windows 
and getting it comes to mind.  Also, an 'everything' ISO will 
fit on an 8 or 16 G datastick, so one can 'pull the full 
archive' and if there is a dependency problem it might be 
resolved.  It is worth keeping a copy around for times like 
this ;)

-- Russ herrold

Problem recreating grub2 menu in SL7 dual boot with Win10

[Bill Maidment]

Hi
In fear and trepidation I ran a BIOS update on my Acer Aspire A515-51G from the 
Win10 part of my dual boot (only Win10 can update the BIOS). On reboot, all I 
get is Win10 (Surprise! Surprise!).
So I booted into an SL7.4 USB recovery mode with chroot /mnt/sysimage and tried 
grub2-install /dev/sda only to be told /usr/lib/grub/x86_64-efi/modinfo.sh 
doesn't exist.
It appears that I need to do yum install grub2-efi-modules (why wasn't this 
done before? I ask).
Anyway, how do I install this while in rescue mode, which doesn't seem to have 
network access? Or is there a network enabling option for rescue mode (like 
there was in SystemRescueCD)?
Am I being dense in my old age?

Cheers
Bill Maidment

Re: Setting Up GRUB

[Chris Schanzle]

On 01/23/2018 12:01 PM, Stephen Isard wrote:

On Tue, 23 Jan 2018 12:04:00 +, Ain't Nobody's Alt 
 wrote:


I had a Win10 and a second partition with a few backups.  That partition
was the "Active" partition according to diskmgmt.msc, which I assume
means it had my bootloader.  I went ahead and moved my backups from that
partition to my Win10 before I installed SL, not considering the
consequences of the location of my bootloader.  I could totally use the
Win10 recovery disc to reinstall the MS bootloader and then reinstall SL
since I just installed it anyway, but I'd rather try and set up GRUB
myself, for the experience.  That said, I have no idea how to start.  I
installed the yum package, but what now?  Can anyone link me to an
article or something to read that will give me an idea of how to begin?

Try "info grub" (without the quotes) from the command line.  You should get a menu with 
"Installation" as the third item and "Booting" as the fourth.
Hope that helps.



What major release (6 or 7) of SL are you installing?

"info grub" works for version 6, use "info grub2" for CentOS 7 (should be 
functionally identical to SL7), as provided by the package grub2-tools:

$ rpm -qf `locate grub2.info.gz`
grub2-tools-2.02-0.65.el7.centos.2.x86_64

Note grub*-install will generally find Windows partitions and set up boot 
entries for you.

But still, "info" doesn't offer lot of hand-holding for dual boot issues; I suspect 
google will provide better info, but who knows?  It might "just work!"  (Until Microsoft 
installs a major update and overwrites your Grub bootloader config.)

You also didn't specify UEFI or BIOS and if Secure Boot was enabled...all these 
options add to the complexity of finding the right solution to any problems.

Good luck!

Re: Setting Up GRUB

[Stephen Isard]

On Tue, 23 Jan 2018 12:04:00 +, Ain't Nobody's Alt 
 wrote:

>I had a Win10 and a second partition with a few backups.  That partition
>was the "Active" partition according to diskmgmt.msc, which I assume
>means it had my bootloader.  I went ahead and moved my backups from that
>partition to my Win10 before I installed SL, not considering the
>consequences of the location of my bootloader.  I could totally use the
>Win10 recovery disc to reinstall the MS bootloader and then reinstall SL
>since I just installed it anyway, but I'd rather try and set up GRUB
>myself, for the experience.  That said, I have no idea how to start.  I
>installed the yum package, but what now?  Can anyone link me to an
>article or something to read that will give me an idea of how to begin?

Try "info grub" (without the quotes) from the command line.  You should get a 
menu with "Installation" as the third item and "Booting" as the fourth.
Hope that helps.

Setting Up GRUB

[Ain't Nobody's Alt]

I had a Win10 and a second partition with a few backups.  That partition
was the "Active" partition according to diskmgmt.msc, which I assume
means it had my bootloader.  I went ahead and moved my backups from that
partition to my Win10 before I installed SL, not considering the
consequences of the location of my bootloader.  I could totally use the
Win10 recovery disc to reinstall the MS bootloader and then reinstall SL
since I just installed it anyway, but I'd rather try and set up GRUB
myself, for the experience.  That said, I have no idea how to start.  I
installed the yum package, but what now?  Can anyone link me to an
article or something to read that will give me an idea of how to begin?

-Aint