Unable to find Windows10 boot menu after Centos 7 Installaion

[hellomister]

Hi,

I am unable to find my Windows 10 boot after I installed Centos 7. No Dual boot found , hope I get some thoughts and help regardingly.
LAPTOP DETAILS - Lenovo Ideapad 320 15IKB 81BH
Boot Menu - Legacy , UEFI enabled

SOURCE - https://www.youtube.com/watch?v=iwwRd_oVaJA
I tried adding windows 10 custom lines in to 40_custom and am getting this error as given below

[root@devops11 ~]# more /etc/grub.d/40_custom
#!/bin/sh
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.

menuentry "Windows10 (loader) (on /dev/sda1)" {
insmod part_msdos
insmod ntfs
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set-root 8E1F-6D4F
chainloader +1

[root@devops11 boot]# cp /etc/grub.d/40_custom /etc/grub.d/40_custom_orig
[root@devops11 boot]# vim /etc/grub.d/40_custom
[root@devops11 boot]# grub2-mkconfig --output=/boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
error: out of memory.
error: syntax error.
error: Incorrect command.
error: syntax error.
Syntax error at line 214
Syntax errors are detected in generated GRUB config file.
Ensure that there are no errors in /etc/default/grub
and /etc/grub.d/* files or please file a bug report with
/boot/grub2/grub.cfg.new file attached.

##########################################################################################

I have tried to capture and post grub2-mkconfig as found from search in this forum grub2-mkconfig entries and other useful info ---
#########################################################################################
[root@devops11 ~]# grub2-mkconfig -o /etc/grub2.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done
[root@devops11 ~]# grub2-mkconfig -o /etc/grub2-efi.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done

[root@devops11 ~]# grub2-mkconfig -o /boot/grub/grub2.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done
[root@devops11 boot]# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done
[root@devops11 boot]# grub2-mkconfig -o /boot/grub2/grub2.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done
#########################################################################################
LSBLK , FDISK -L DF -H BLKID COMMANDS OUTPUT

[root@devops11 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931.5G 0 disk
├─sda1 8:1 0 260M 0 part
├─sda2 8:2 0 16M 0 part
├─sda3 8:3 0 60.1G 0 part
├─sda4 8:4 0 244.1G 0 part /media/bbsda4
├─sda5 8:5 0 25G 0 part
├─sda6 8:6 0 1000M 0 part
├─sda7 8:7 0 1M 0 part
├─sda8 8:8 0 1G 0 part /boot
└─sda9 8:9 0 600G 0 part
├─centos-root 253:0 0 50G 0 lvm /
├─centos-swap 253:1 0 5.8G 0 lvm [SWAP]
└─centos-home 253:2 0 544.2G 0 lvm /home
sr0 11:0 1 1024M 0 rom

[root@devops11 boot]# fdisk -l
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: 210EAB63-5977-4E30-81F4-AD7D54C88907


# Start End Size Type Name
1 2048 534527 260M EFI System EFI system partition
2 534528 567295 16M Microsoft reser Microsoft reserved partition
3 567296 126556159 60.1G Microsoft basic Basic data partition
4 126556160 638556159 244.1G Microsoft basic Basic data partition
5 1899046912 1951475711 25G Microsoft basic Basic data partition
6 1951475712 1953523711 1000M Windows recover Basic data partition
7 638556160 638558207 1M BIOS boot
8 638558208 640655359 1G Microsoft basic
9 640655360 1899046911 600G Linux LVM

Disk /dev/mapper/centos-root: 53.7 GB, 53687091200 bytes, 104857600 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-swap: 6241 MB, 6241124352 bytes, 12189696 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: 584.4 GB, 584363016192 bytes, 1141334016 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

[root@devops11 boot]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 5.7G 0 5.7G 0% /dev
tmpfs 5.7G 260M 5.5G 5% /dev/shm
tmpfs 5.7G 9.9M 5.7G 1% /run
tmpfs 5.7G 0 5.7G 0% /sys/fs/cgroup
/dev/mapper/centos-root 50G 18G 33G 35% /
/dev/sda4 245G 90G 155G 37% /media/bbsda4
/dev/mapper/centos-home 544G 480G 65G 89% /home
/dev/sda8 1014M 416M 599M 42% /boot
tmpfs 1.2G 28K 1.2G 1% /run/user/1000

[root@devops11 boot]# blkid
/dev/sda1: LABEL="SYSTEM_DRV" UUID="8E1F-6D4F" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="9b352704-3cc2-405f-91a8-fad8ef0b5a8a"
/dev/sda3: LABEL="Windows" UUID="F06022AB6022790C" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="dc4d5bac-1db1-420e-af5d-7d3de0f4aafc"
/dev/sda4: LABEL="Data" UUID="827E27837E276EDB" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="011fb029-7e4a-408a-bafd-b7d071aedfd6"
/dev/sda5: LABEL="LENOVO" UUID="0AE6172FE6171A91" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="39337a28-a88b-4541-aebe-798d877a5037"
/dev/sda6: LABEL="WINRE_DRV" UUID="BA26256926252839" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="e8ea1ac9-2aab-4f83-818e-85b35e28da80"
/dev/sda8: UUID="27102b04-127f-4e9b-b438-22e1321fde5f" TYPE="xfs" PARTUUID="195d72e1-d91f-4d9b-acb7-66dc9228c3f9"
/dev/sda9: UUID="7WqGpc-JYDC-UIE2-bcEH-V6Ap-reYx-T2SHpI" TYPE="LVM2_member" PARTUUID="86c2eab8-f50f-47e1-bb8f-e763b96dce93"
/dev/mapper/centos-root: UUID="4ad4105b-63e4-44e7-b42b-4c6b191563ab" TYPE="xfs"
/dev/mapper/centos-swap: UUID="5a8bf7b9-3409-42c6-b576-811c0854141b" TYPE="swap"
/dev/mapper/centos-home: UUID="b0b82511-aeac-4fa7-808d-29c606f38bb5" TYPE="xfs"
/dev/sda2: PARTLABEL="Microsoft reserved partition" PARTUUID="e0b2b95c-91a2-4b80-8542-9918bf4f44bb"
/dev/sda7: PARTUUID="8492445b-9a59-417b-b078-fe957dad8e0f"

#########################################################################################
OS-PROBER O/P
===NIL--- no output just returns to syntax
#########################################################################################
[root@devops11 boot]# cat /etc/default/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
GRUB_DISABLE_RECOVERY="true"
#########################################################################################

[hellomister]

##########################################################################################
Reverted teh 40_custom entris by commenting as given below ... after which the
grub2-mkconfig executed without errors , please direct me to the right solution so that I
can recover my Windows10 as its my core working OS.

[root@devops11 boot]# vim /etc/grub.d/40_custom
[root@devops11 boot]# cat /etc/grub.d/40_custom
#!/bin/sh
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.

#menuentry "Windows10 (loader) (on /dev/sda1)" {
#insmod part_msdos
#insmod ntfs
#set root='(hd0,msdos1)'
#search --no-floppy --fs-uuid --set-root 8E1F-6D4F
#chainloader +1
[root@devops11 boot]# grub2-mkconfig -o /etc/grub2.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.4.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.4.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.27.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.27.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.10.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-957.5.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-957.5.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aceb102394644a579a988b04c2e0c2cb
Found initrd image: /boot/initramfs-0-rescue-aceb102394644a579a988b04c2e0c2cb.img
done

##########################################################################################

[TrevorH]

You say that your machine is in UEFI mode yet your grub.cfg is in the location that is used for Legacy BIOS machines. That indicates to me that you probably used one of the many broken USB stick utilities to copy our iso image to your USB stick. Many of them are utterly broken and should never be used - they attempt to be "clever" and rewrite the iso image as they copy it and the broken ones remove the UEFI boot capability from the iso so that it will not boot in UEFI mode on a UEFI capable machine. The machine then falls back to Legacy BIOS mode and installs into the wrong place. As a side effect of that it also means that grub cannot see any of the previous UEFI based installs on the machine since it thinks it's in legacy mode.

What USB stick utility did you use to create your USB stick?

[owl102]

I second what TrevorH wrote. Since this is partitioned in GPT, Windows is only able to boot from this media in UEFI mode, therefore it's save to assume it has been installed in UEFI mode (by you or the manufacturer). Therefore CentOS must be installed in UEFI mode as well, otherwise you won't get a working dual boot system, at least not when using Grub as boot manager. (*) This is not a deficit of Grub, but a deficit of the PC architecture: Once something has been booted in Legacy mode (like Grub), it's not possible to start something else from there in UEFI mode.

After installation of CentOS in UEFI mode the Windows boot entry should appear at no cost, there is no custom grub file necessary or anything like that. The menu entry for booting Windows should just be there and it should just work, right after installation of CentOS.

(*) But you could always use the boot manager of your PC BIOS/UEFI. How to enter this boot menu differs from PC manufacturer to manufacturer, usually you need to press a key like F12 during POST screen.

[hellomister]

I have not used any usb stick nor any CD/DVD till date from the date of Centos 7 installation few months back (Centos 7 DVD was used for installation). We are not allowed to use it while in the training.
Yes I am a new bee to Centos 7 being a Windows user , its a bit this and that from Centos forums I ran this grub2-mkconfig -o /etc/grub2.cfg and grub2-efi.cfg commands both at boot & etc path. Thats all I know. Since I got the error rolled back and posted here.
Another thing is that I tried changing the bios settings boot menu to UEFI but it doesnt boot to HDD linux , searching for media. Again rolled back to legacy and second option changed to UEFI support enabled. Nothing much was done.
Since I am new to linux OS I could not go further without deep knowledge experience.
I am migrating from Windows to Centos and so am in adaption exercise. As of now both Windows 10 and Centos 7 environment is critical. So looking for a safe way to come out of this situation.
Can I reinstall Centos 7 without affecting the environment like installed programs , training dev environment , etc as its more work if OS crash then its a 3 to 5 days of work lost , need to do it from scratch.

For information sake this laptop came with a preloaded Windows 10 and all partitions factory default. I just resized partition and installed on free space.

[owl102]

Can I reinstall Centos 7 without affecting the environment like installed programs , training dev environment , etc as its more work if OS crash then its a 3 to 5 days of work lost , need to do it from scratch.

I haven't done this myself, but it should be possible. First of all add an entry in /etc/fstab to mount the EFI partition (/dev/sda1) to /boot/efi:

Code: Select all

/dev/sda1 /boot/efi vfat defaults 0 1

Afterwards boot the CentOS installation media in Rescue mode. (In UEFI mode. Try "efibootmgr", this command should output the EFI boot menu entries and not give an error message. If you get an error message, you haven't booted in UEFI mode.) Then chroot your system and re-install grub:

Code: Select all

# yum reinstall grub2-efi grub2-efi-modules shim
# grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg

Disclaimer: I think it should work this way. But since I never have done this, I cannot tell if it really works this way.

[hellomister]

Is it oka to provide entries of all lenovo and windows sda partitions in etc/fstab ?
Any other alternatives other than the disclaimer part as I don't have any linux expert resources around me to help in cases of disaster ?

[hellomister]

I am struck up on what or how to go forward ? Any ideas to restore my Windows 10 boot. I can forgo Centos if that is all the goddamm way out ...
but there should be a way out of this peculiar situation.

[owl102]

Any ideas to restore my Windows 10 boot.

The Windows 10 boot should still be there. Currently the UEFI/BIOS of your computer boots the HD/SSD in Legacy Mode, and therefore Grub is shown (without Windows 10 boot entry). But if you tell your UEFI/BIOS of your computer to boot the HD/SSD in UEFI Mode instead, Windows 10 should boot instead.

Many computers have a UEFI boot menu which could be entered by pressing a specific key at POST screen.

To check if/that the Windows 10 UEFI boot entry is still there, boot a Linux Live distribution from USB in UEFI mode, start a terminal and enter "efibootmgr" (as user or root). If the output is something like

Code: Select all

...
Boot0000* Windows Boot Manager
...

the Windows 10 boot entry is still in UEFIs nvram.

[hellomister]

When I press f2 after starting my lenovo laptop , goes in to bios , then under boot options i select UEFI , then restart after saving the EFI boot searches for long and again goes back to restart and the same process loops. If I select the second option to legacy then after searching for boot media then it boots in to linux.