mjhjmtu

I installed Windows 10 on my SSD and then CentOS 7. After the CentOS install's final reboot, there isn't an entry in grub for my Windows 10 stuff.

Here's fdisk -l

isk /dev/sda: 1000.2 GB, 1000204886016 bytes, 1953525168 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: gpt
Disk identifier: 873E25DD-2CDA-11E9-AD60-38BAF8FA5F68


# Start End Size Type Name
 1 2048 1026047 500M Microsoft basic 
 2 1026048 316117075 150.3G Microsoft basic 
 3 316119040 316323839 100M EFI System 
 4 316323840 317951999 795M Windows recover 
 5 317968384 635920383 151.6G Microsoft basic 
 6 635936768 953888767 151.6G Microsoft basic 
 7 953905152 1052209151 46.9G Microsoft basic 
 8 1052225536 1117761535 31.3G Linux filesyste 
 9 1117777920 1150545919 15.6G Linux filesyste 
10 1150562304 1183330303 15.6G Linux filesyste 
11 1183346688 1216114687 15.6G Linux filesyste 
12 1216131072 1248899071 15.6G Linux filesyste 
13 1248915456 1281683455 15.6G Linux filesyste 
14 1281699840 1380003839 46.9G Linux swap 
15 317952000 317956095 2M BIOS boot 
16 1697988608 1953509375 121.9G Linux filesyste 
17 1380003840 1697988607 151.6G Linux LVM 

Disk /dev/mapper/centos-root: 162.8 GB, 162806104064 bytes, 317980672 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

So I edited /etc/grub.d/40_custom like so:

#!/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 "Windows 10" 
 set root(hd0,3)
 chainloader +1
 

And then ran:

grub2-mkconfig --output=/boot/grub2/grub.cfg

When I rebooted, and selected the menu entry for "Windows 10", I got this:

Error: not an assignment invalid signature

I'm stuck, how can I get the Windows stuff in my grub so I can boot from either OS?

Someone in another forum told me not to use CSM.

Well... out of complete frustration, I wiped the disk, set CSM to disabled (ASUS lied), installed Windows, installed CentOS again.

Interestingly enough, the partition wizard had an option for /boot/efi as a mount point this time! That was NOT there with CSM enabled.

So I selected /boot/efi and when the install finished, I had both Windows and Linux in my boot menu!