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how to dual boot fedora 27 and fedora 28 [closed]

asked 2018-05-02 03:41:39 -0600

sederb1953 gravatar image

updated 2018-05-02 17:39:37 -0600

I am running fedora 27 and because of issues with Draftsight have installed f28 where draftsight works. I have searched for info on dual booting two fedora installs but cannot find enough info to achieve this. F27 is on /dev/sdb and F28 is on /dev/sda any help in achieving this would be appreciated. I checked out the grub2 wiki on fedora project and ran the commands suggested there (grub2-mkconfig) and (grub2-mkconfig -o /boot/grub2/grub.cfg). F28 system was found on /dev/sda2 but when i restarted the pc F28 did not come up in the grub OS list only the last 3 f27 updates. The grub2-mkconfig output suggested modifying /etc/grub.d/40_custom but as there is no example in this file I don't know what should be placed there. PC is an older desktop with bios booting MBR drives. Not a newbie but not fully conversant with the inner workings of linux or grub.

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Closed for the following reason the question is answered, right answer was accepted by sederb1953
close date 2018-05-04 19:54:34.940811


Can you explain this a bit more? I'd understand if the issue were reversed, and you needed F27 to keep your application running, but since it works in F28, why not just upgrade?

mattdm gravatar imagemattdm ( 2018-05-03 19:31:20 -0600 )edit

F28 is still beta so don't want to fedup just yet as i have too much reliance on the data in the machine.

sederb1953 gravatar imagesederb1953 ( 2018-05-04 19:55:32 -0600 )edit

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answered 2018-05-04 19:54:06 -0600

sederb1953 gravatar image

Now it works properly. Not sure what is did wrong before but simply ran "os-prober" then "grub2-mkconfig -o /boot/grub2/grub.cfg" and restarted and F28 was in the grub menu. Maybe running grub2-mkconfig instead of os-prober was the issue? Anyway it now works and all is good. i can continue to play with f28 beta. This issue can now be closed.

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answered 2018-05-03 17:49:11 -0600

sederb1953 gravatar image

Villykruse, I can go back to the bios and select a different boot drive but wanted to use grub2 menu as this is quicker than having to enter bios setup. I have found some info on the 40custom format but cannot get the right location set for the kernel. Below is what i have tried last. The f28 boot partition is /dev/sda1 and root is /dev/sda2. The filenames are copied straight from looking at the boot partition with thunar. The error from grub is something like "vmlinuz not found. you must load linux first" can't remember it exactly. menuentry 'Custom Entry' { set root='hd0,2' echo 'Loading Linux F28 Beta'
linux (hd0,1)vmlinuz-4.16.5-300.fc28.x86
64 echo 'Loading initial ramdisk ...' initrd (hd0,1) initramfs-4.16.5-300.fc28.x86_64.img } I had tried using /boot instead of (hd0,1) but no change, also set root="hd0,1". same error message appears.

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This is not an answer to your question, and these lines should rather be appended to your original question.

villykruse gravatar imagevillykruse ( 2018-05-03 23:53:46 -0600 )edit

answered 2018-05-03 01:30:51 -0600

villykruse gravatar image

updated 2018-05-03 23:52:29 -0600

I have done this for quite a while, and it works without modifying /etc/grub.d/40_custom. I don't have UEFI so this is pure MBR booting. You may need to run fsck on the root file system from the other system before running grub2-mkconfig.

I could also select to boot from the other disk in the BIOS boot setup, and that workes perfectly as well.

os-prober is used by grub2-mkconfig to locate the other installed operating systems. Following shows that it found one.

# os-prober 
/dev/sdb5:Fedora 28 (Twenty Eight):Fedora:linux

grub2-mkconfig will then read the information from sdb5 and sdb2, which in this case contains the boot partition corresponding to the root partition sdb5

# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found theme: /boot/grub2/themes/starfield/theme.txt
Found linux image: /boot/vmlinuz-4.16.5-300.fc28.x86_64
Found initrd image: /boot/initramfs-4.16.5-300.fc28.x86_64.img
Found linux image: /boot/vmlinuz-4.16.4-300.fc28.x86_64
Found initrd image: /boot/initramfs-4.16.4-300.fc28.x86_64.img
Found linux image: /boot/vmlinuz-4.16.4-200.fc27.x86_64
Found initrd image: /boot/initramfs-4.16.4-200.fc27.x86_64.img
Found linux image: /boot/vmlinuz-4.16.3-200.fc27.x86_64
Found initrd image: /boot/initramfs-4.16.3-200.fc27.x86_64.img
Found linux image: /boot/vmlinuz-4.15.17-300.fc27.x86_64
Found initrd image: /boot/initramfs-4.15.17-300.fc27.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-dc5c0cbdda03c984024a73e54bad769b
Found initrd image: /boot/initramfs-0-rescue-dc5c0cbdda03c984024a73e54bad769b.img
Found memtest image: /boot/elf-memtest86+-5.01
Found Fedora 28 (Twenty Eight) on /dev/sdb5

Notice this line Found Fedora 28 (Twenty Eight) on /dev/sdb5 which tells me it created menu entries for loading linux from sdb5.

Keep 40_custom as it was at install time:

# cat 40_custom
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
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