Problems adding Windows OS to the grub menu

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tdimri
Posts: 1
Joined: 2019/03/21 17:41:52

Problems adding Windows OS to the grub menu

Post by tdimri » 2019/03/21 17:57:35

Hi All,

This is my first time installing Linux. And I decided to go for a dual boot on my laptop alongside Windows 10.
Linux seems to be working fine when i boot in "Legacy Mode" (that's what it was installed in, because none of my drives were being listed during installation if i switched to UEFI mode).
Now when i try to add Windows drive to the grub menu, and i try to fetch the Drive details using <fdisk -l> for entering in my grub configs. I can't exactly see the SSD in prints. Here is my output, when i run that command:-

------------------------------------------------------------------------------------------------------------
Disk /dev/nvme0n1: 256.1 GB, 256060514304 bytes, 500118192 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x2db036b5

Device Boot Start End Blocks Id System
/dev/nvme0n1p1 1 4294967295 2147483647+ ee GPT
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes, 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: gpt
Disk identifier: 4F0B0960-179A-4A25-8D01-FEC955E1C746


# Start End Size Type Name
1 2048 264191 128M Microsoft reser Microsoft reserved partition
2 264192 1748723711 833.7G Microsoft basic Basic data partition
3 1748723712 1748725759 1M BIOS boot
4 1748725760 1933922303 88.3G Linux LVM
5 1933922304 1953452031 9.3G Microsoft basic

Disk /dev/mapper/centos-swap: 32.0 GB, 32002539520 bytes, 62504960 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/mapper/centos-home: 62.8 GB, 62813896704 bytes, 122683392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

------------------------------------------------------------------------------------------------------------

My Windows partitions are accessible to me after mounting on this location - "/run/media/username/OS"

My Laptop Configs:-
- Intel Core i7 7th Generation.
- SSD (Windows Drive)
- HDD (Two Partitions - NTFS for data and one as GPT for Linux OS)

It would be really helpful, if someone could please help with this. And please let me know if i forgot to put up some essential information.

Cheers
-Tanay Dimri

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TrevorH
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Posts: 33202
Joined: 2009/09/24 10:40:56
Location: Brighton, UK

Re: Problems adding Windows OS to the grub menu

Post by TrevorH » 2019/03/21 18:04:05

How did you create the USB Stick that you used to do the install?
The future appears to be RHEL or Debian. I think I'm going Debian.
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke

desertcat
Posts: 843
Joined: 2014/08/07 02:17:29
Location: Tucson, AZ

Re: Problems adding Windows OS to the grub menu

Post by desertcat » 2019/03/24 08:23:01

You have a 1TB SSD?!? DROOL!!! :mrgreen:

Criminalpython
Posts: 8
Joined: 2019/07/09 21:17:31
Location: Brighton

Re: Problems adding Windows OS to the grub menu

Post by Criminalpython » 2019/07/09 23:48:08

I think I have the same problem, have you solved this?

owl102
Posts: 413
Joined: 2014/06/10 19:13:41

Re: Problems adding Windows OS to the grub menu

Post by owl102 » 2019/07/10 06:16:40

Since MS-Windows was installed in UEFI mode and CentOS was not, there is no way of getting a working MS-Windows boot entry in Grub. To make this happen both need to be installed in the same mode, either both in UEFI mode or both in Legacy/CSM mode.

The only way to switch OS in this non-matching constellation is to select it in the UEFI/BIOS boot menu. (On most PCs one have to press F11 during POST screen.)
German speaking forum for Fedora and CentOS: https://www.fedoraforum.de/

Criminalpython
Posts: 8
Joined: 2019/07/09 21:17:31
Location: Brighton

Re: Problems adding Windows OS to the grub menu

Post by Criminalpython » 2019/07/12 18:36:28

How do I get back into windows? I understand I cant add it to grub but is there a way to force myself into windows? Seeing as grub overwrite windows boot manager is there a way to get back into windows?

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TrevorH
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Posts: 33202
Joined: 2009/09/24 10:40:56
Location: Brighton, UK

Re: Problems adding Windows OS to the grub menu

Post by TrevorH » 2019/07/12 18:50:58

You never answered the questions you were asked so at the moment, all we have to go on is guesswork as to what the problem is.

I suggest you stick to the thread you opened yourself about this problem. It's a better place to discuss your issue than this one which was started by someone else about their problem (which may not be the same as yours).
The future appears to be RHEL or Debian. I think I'm going Debian.
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 and 6 are deadest, do not use them.
Use the FAQ Luke

owl102
Posts: 413
Joined: 2014/06/10 19:13:41

Re: Problems adding Windows OS to the grub menu

Post by owl102 » 2019/07/13 08:58:47

Regarding the problem of the original questioner: Since the disk is formatted as GPT MS-Windows is (only) running in UEFI mode. And since there is a BIOS boot partition on the disk, CentOS was installed in Legacy/CSM mode. So there is simply no possibility to get a working MS-Windows entry in Grub.

The solution is to install both in the same mode, either UEFI or Legacy/CSM.
German speaking forum for Fedora and CentOS: https://www.fedoraforum.de/

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