Dual boot uefi with Windows

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patosx
Posts: 2
Joined: 2015/01/27 16:06:22

Dual boot uefi with Windows

Post by patosx » 2015/01/27 16:21:01

Hi everyone,

I installed Centos 7 x86_64 in dual boot with Windows 8.1.
There is no problem except when I use Windows at boot time, grub2 menu disapear when I boot again.

However I found out a way to display grub2 menu anyway, but it's rather complex :
- Enter Bios at boot time and set boot mode to legacy, save and reboot
- The system cannot start and display a message like "no proper device found ..."
- Reboot again, enter Bios and set boot mode to UEFI, this time grub2 menu is displayed

Is there a way making this menu visible a boot time without this complex manipulation ?

I precise that I enabled/disabled secure boot in bios but it's the same result.
Same result too if i disable Fast startup in Windows.

patosx
Posts: 2
Joined: 2015/01/27 16:06:22

Re: Dual boot uefi with Windows

Post by patosx » 2015/01/28 09:46:10

Finaly I workarounded the problem by creating two boot uefi partitions (/boot/efi on /dev/sda1 for Windows and /boot/efi on /dev/sda2 for Centos).
Now I've juste to press a key at startup (F12 in my case) and choice the correct uefi boot.

I noticed if both Windows and Centos boot are installed on the same uefi partition, "Windows boot" always go first.
When you set boot mode to Legacy and after to uefi again, the first time the system boot on UEFI harddrive but next time uefi harddrive is replaced by Windows uefi.

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