Dual boot with RHEL 7.6 beta
I'm trying to do dual boot with CentOS 7.5 and RHEL 7.6 beta. I know there is a solution available[1], but it seems that the beta software is not working. I tried the procedure wit CentOS 7.5 and Fedora 28, and works fine. With Red Hat, it presents the CentOS prompt, but it tries to boot the Red Hat instead, and fails. I see that progress bar at the bottom of the screen. My /boot/grub2/grub.cfg is intact, that is, CentOS only.
The question is if this is because it's a beta version or is this really the way Red Hat is going to work?
Thanks for your attention.
Regards.
Marcelo
[1]
https://access.redhat.com/solutions/45409
Responses
Hi Marcelo,
You seem to have the systems installed on a machine which has a Legacy BIOS, because on modern machines with UEFI based
BIOS each system has its own boot loader located in a separate directory on the efi partition. Now to your problem : What you
describe can happen after a new kernel on one of the systems gets installed. The solution is to update the GRUB configuration
first on the system where the new kernel got installed and then boot into the other system and update the configuration there.
So, this means that you have to execute sudo grub2-mkconfig -o /boot/grub2/grub.cfg manually on both systems. :)
Regards,
Christian
Hi Marcelo,
The main problem is that CentOS and RHEL are basically the same thing, especially when it comes
to the boot loader here. What you can try is to boot into CentOS rescue mode and reinstall GRUB.
If that also doesn't lead to the desired results, the only thing left would be to add RHEL manually.
I don't know if it works, but give it a try ... execute sudo vi /etc/grub.d/40_custom, add the boot menu entry and then sudo grub2-mkconfig -o /boot/grub2/grub.cfg afterwards. :)
Regards,
Christian
Hi Marcello,
Well, in this case you should consider to report that Anaconda bug -> https://bugzilla.redhat.com/
Regards,
Christian
Hello everybody ! I have a windows 7 on a SSD disk and RedHat 7.6 Beta on an other one. Windows was installed first. I have installed the RH system, but my computer boot only on Windows. grub2 is installed on the RH system but Windows does not appears in the grub.cfg file. How can I update the grub.cfg file ? What line for windows, can I write in the config file ? Thank you so much for your answers. Alain
Hi Alan,
Assuming you have a Legacy BIOS ... there can be only one boot loader installed in the Master Boot Record. On
machines with UEFI BIOS you can manage the boot loaders with the efibootmgr tool. As you have installed the
systems on different disks, I suggest to use the Windows boot loader and add RHEL there. Here's what you need
to do : First copy and export the Linux boot sector by booting from a Linux "Live" medium like GParted ... open
a terminal there and execute the following two commands :
sudo mount /dev/sdYY /mntdd if=/dev/sdXX of=/mnt/linux.bin bs=512 count=1
Note : sdXX = the RHEL system partition | sdYY = the Windows system partition
Shutdown the PC - remove the Linux Live medium - start the PC - boot Windows - open command prompt as administrator and execute the following three commands :
bcdedit /create /d <name> /application bootsectorbcdedit /set {***} device partition=c:bcdedit /set {***} path \linux.bin
Note : *** = the identifier of the new entry in the BCD store | <name> = the name of the system (e.g. RHEL)
Reboot the computer and now you will see the RHEL entry in the Windows boot menu ... boot into RHEL ... :)
Regards,
Christian
Thank you so much Christian. I not hope to read a so good and complete answer, but it's magic to read you. Many many thanks Christian. Alan
Hi everybody :-) is there an option existing to install and config grub in the same time of the RedHat Installation ? I don't find any thing like this to perform this way while installing RedHat on my second PC. Is there only the possibility to update the boot sector ? Nothing in the RedHat parameters to configurate grub ? Thank you all for your answers
Hi Alan,
When you install the system, GRUB gets installed and configured automatically. If you want to change something,
you have to do this after the installation is finished. By the way, this question would have better been posted as a
new question - right because more members can find it ... this thread is specifically about dual booting with RHEL Beta. :)
Regards,
Christian
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