Dual boot BIOS mode

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lattimro
Posts: 28
Joined: 2021/06/14 13:38:19

Dual boot BIOS mode

Post by lattimro » 2021/07/24 18:24:21

Hi everyone,

I have installed CentOS 8 in BIOS mode also Windows 10 is in BIOS mode and the os-prober does not see anything (I do not know if it have an output on BIOS mode).

I check centos for BIOS mode:

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[root@localhost brad]# ls /sys/firmware/
acpi  dmi  memmap  qemu_fw_cfg
[root@localhost brad]# efibootmgr -v
EFI variables are not supported on this system.
[root@localhost brad]# efivar -l
efivar: error listing variables: Function not implemented
[root@localhost brad]# os-prober
[root@localhost brad]# 
The workaround was to add to /etc/grub.d/40_custom the lines:

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menuentry "Windows 10" {
         set root=(hd0,1)
         chainloader +1
         }
and regenerate the grub menu:

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grub2-mkconfig --output=/boot/grub2/grub.cfg
Now dual boot works fine but I am wondering if this is the correct mode to enable dual boot. Thanks!!!

owl102
Posts: 404
Joined: 2014/06/10 19:13:41

Re: Dual boot BIOS mode

Post by owl102 » 2021/07/24 20:25:45

lattimro wrote:
2021/07/24 18:24:21
os-prober does not see anything (I do not know if it have an output on BIOS mode).
Yes, it should have an output. Is the package ntfs-3g installed? If not then please install it and try "os-prober" again.
German speaking forum for Fedora and CentOS: https://www.fedoraforum.de/

lattimro
Posts: 28
Joined: 2021/06/14 13:38:19

Re: Dual boot BIOS mode

Post by lattimro » 2021/07/25 01:11:05

Thank you so much, I installed and works fine!

to be honest, I read other posts and they also said ntfs-3g is required but I thought it will be for read/write Windows NTFS. As I did not have this purpose I ignored it.
ntfs-3g is an NTFS driver, which can create, remove, rename, move files, directories, hard links, and streams; it can read and write files, including streams, sparse files and transparently compressed files; it can handle special files like symbolic links, devices, and FIFOs; moreover it provides standard management of file ownership and permissions, including POSIX ACLs.
It comes in two variants ntfs-3g and lowntfs-3g with a few differences mentioned below in relevant options descriptions.
The volume to be mounted can be either a block device or an image file.
Last edited by lattimro on 2021/07/26 02:57:13, edited 1 time in total.

owl102
Posts: 404
Joined: 2014/06/10 19:13:41

Re: Dual boot BIOS mode

Post by owl102 » 2021/07/25 07:39:56

lattimro wrote:
2021/07/25 01:11:05
to be honest, I read other posts and the also said ntfs-3g is required but I thought it will be for read/write Windows NTFS.
You are totally correct but in BIOS mode os-prober needs to read NTFS partitions to take a look if there is a MS-Windows installed onto it, therefore ntfs-3g is required here.
German speaking forum for Fedora and CentOS: https://www.fedoraforum.de/

lattimro
Posts: 28
Joined: 2021/06/14 13:38:19

Re: Dual boot BIOS mode

Post by lattimro » 2021/07/26 02:58:04

absolutely, totally agree! Thank you so much, much appreciated.

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kraomohsin75
Posts: 3
Joined: 2021/07/31 12:08:30
Location: Karachi
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Re: Dual boot BIOS mode

Post by kraomohsin75 » 2021/08/01 13:28:08

Hi there,

What is the purpose of "chainloader +1"
why windows entry in grub is different with linux distro entry?


many thanks,
rao
Many Thanks,
Rao

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jlehtone
Posts: 3657
Joined: 2007/12/11 08:17:33
Location: Finland

Re: Dual boot BIOS mode

Post by jlehtone » 2021/08/01 13:46:47

kraomohsin75 wrote:
2021/08/01 13:28:08
What is the purpose of "chainloader +1"
why windows entry in grub is different with linux distro entry?
GRUB does not have specific support for MS Windows. The chain loading is a more generic method.

https://www.gnu.org/software/grub/manua ... hainloader
https://www.gnu.org/software/grub/manua ... ading.html

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