Installing CentOS 7 manually on hybrid MBR/GPT systems
Posted: 2019/08/15 11:44:44
Hello to all!
Here follows a somewhat special topic about installing CentOS 7 at hybrid MBR/GPT based systems.
(https://www.rodsbooks.com/gdisk/hybrid.html)
Apple uses this principle on their Intel based computers since almost 13 years.
I am now stuck at the point that I have to install CentOS 7 manually in MBR mode. This can't be done with the CentOS installer, because Linux is more intelligent than Windows. For example, when booting in legacy CSM "bios" mode, Windows doesn't care about any EFI partitions and is installing fine with old style MBR at the selected "Windows HD". When CentOS 7 is booting in legacy CSM mode it detects the EFI environment (from Mac OS X) and want to proceed on that way. The CentOS installer won't continue the installation with MBR style because it detects this partition layout as non-conformant. This is true in any other case, but not at hybrid MBR/GPT Apple systems.
Exist there now a way to enforce CentOS to use the MBR part of the hybrid MBR/GPT partition scheme? At the moment it looks like:
The idea is to use partition 4 as main active "Linux HD". (Note, it could be possible that I had to kill sda 5 because of some strange limitations of the MBR/GPT scheme.)
As everybody knows, Apple uses at their Intel based systems quite special EFI implementations. First systems were EFI32 based, in 2007 Apple switched to EFI64 and since 2009 the iMac Models had more UEFI functions like GOP video implemented.
Well it is possible to install CentOS 7 alone at a blank SSD. Because there is no EFI information present, CentOS is installing fine in MBR mode.
The absolutely best would be to install CentOS 7 in native EFI mode. However, that's especially on older EFI32 based Apple systems a very hard task. There are some reports that this can work but it needs deeper Linux skills. Main problems are:
- Apple doesn't expose the vbios in EFI mode, it is only avaiable for a short time during power up
- EFI32 to EFI64 handover, for booting a 64bit CentOS 7 with a 64bit Intel C2D CPU on an EFI32 based system
The later one doesn't seems to be supported by GRUB, it could work with rEFInd. More information about that very complex topic can be found here: https://forum.artixlinux.org/index.php/ ... ml#msg4608
Here follows a somewhat special topic about installing CentOS 7 at hybrid MBR/GPT based systems.
(https://www.rodsbooks.com/gdisk/hybrid.html)
Apple uses this principle on their Intel based computers since almost 13 years.
I am now stuck at the point that I have to install CentOS 7 manually in MBR mode. This can't be done with the CentOS installer, because Linux is more intelligent than Windows. For example, when booting in legacy CSM "bios" mode, Windows doesn't care about any EFI partitions and is installing fine with old style MBR at the selected "Windows HD". When CentOS 7 is booting in legacy CSM mode it detects the EFI environment (from Mac OS X) and want to proceed on that way. The CentOS installer won't continue the installation with MBR style because it detects this partition layout as non-conformant. This is true in any other case, but not at hybrid MBR/GPT Apple systems.
Exist there now a way to enforce CentOS to use the MBR part of the hybrid MBR/GPT partition scheme? At the moment it looks like:
Code: Select all
sda 1 EFI System Partition
sda 2 HFS+
sda 3 HFS+
sda 4 / (includes root, boot, home)
sda 5 swap
As everybody knows, Apple uses at their Intel based systems quite special EFI implementations. First systems were EFI32 based, in 2007 Apple switched to EFI64 and since 2009 the iMac Models had more UEFI functions like GOP video implemented.
Well it is possible to install CentOS 7 alone at a blank SSD. Because there is no EFI information present, CentOS is installing fine in MBR mode.
The absolutely best would be to install CentOS 7 in native EFI mode. However, that's especially on older EFI32 based Apple systems a very hard task. There are some reports that this can work but it needs deeper Linux skills. Main problems are:
- Apple doesn't expose the vbios in EFI mode, it is only avaiable for a short time during power up
- EFI32 to EFI64 handover, for booting a 64bit CentOS 7 with a 64bit Intel C2D CPU on an EFI32 based system
The later one doesn't seems to be supported by GRUB, it could work with rEFInd. More information about that very complex topic can be found here: https://forum.artixlinux.org/index.php/ ... ml#msg4608