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https://github.com/andrey-malets/win-boot

Stuff necessary to boot Windows from GPT-partitioned drive in BIOS with GNU GRUB bootloader
https://github.com/andrey-malets/win-boot

boot gpt windows-7

Last synced: 4 months ago
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Stuff necessary to boot Windows from GPT-partitioned drive in BIOS with GNU GRUB bootloader

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README 

        
### Overview



This is a set of scripts and configurations to succesfully install and boot

Windows 7 and 10 from GPT-partitioned drive on a system with BIOS.

This may be convenient if you benefit from GPT features such as partition

labeling, unique GUIDs and raised partition count/size limits.



Windows does not permit this by default, the solution is to create a small

MBR-partitioned virtual drive and place boot-related files to it, so that

Windows will treat this virtual drive as real boot drive and perform all the

boot configuration there. The drive then gets attached automatically at every

boot so all boot-related configuration tasks which are run after installation

(BCD specialization step, updates etc.) complete succesfully.



### Setup procedure



Setup can be accomplished in the following way:



1. Partition your hard drive with GPT using any external tool available. For

  example, using GNU parted this may be like the following:

  ```

  (parted) mklabel gpt

  (parted) mkpart primary 0% 10MB

  (parted) mkpart primary ext4 10MB 210MB

  (parted) mkpart primary ntfs 210MB 100%

  (parted) set 1 bios_grub on

  ```

  This will create small 10MB primary partition at the very beginning with flag

  necessary to install GRUB into GPT drive, and also 200MB ext4 partition

  where GRUB root directory will reside.



  Also here we create third NTFS partition for Windows which spans to the end

  of the drive (change this for your needs).



2. Format and mount your GRUB root partition.



3. Install GRUB to your hard drive using `grub-install` and partition formatted

  in the previous step as boot directory.



4. Install [`grub.cfg`](grub.cfg) and MEMDISK from SysLinux into boot directory.



5. You need Windows PE bootable image with ImageX installed into it (does not

  come by default) and Windows setup DVD. Boot your computer to Windows PE to

  get access to PE command prompt.



6. Format third partition of your hard drive, for example using DiskPart

  (assuming disk #0 is your hard drive):

  ```

  DISKPART> select disk 0

  DISKPART> select partition 3

  DISKPART> format label="Windows 7" quick

  DISKPART> assign letter=c

  ```



7. Install Windows using ImageX (be careful with the letter of your CD/DVD

  here, this assumes D: is your Windows setup DVD):

  ```

  X:\> imagex /apply D:\sources\install.wim 1 c:

  ```



8. Copy [`boot/`](boot/) directory from this repository to C:\boot (for example

  using Samba share).



9. Execute [`C:\boot\create.cmd`](boot/create.cmd). This will create VHD drive

  and place all necessary boot files in it.



10. The next step is crucial for the whole setup. You should reboot your

  machine into new Windows installation and mount the boot VHD drive manually

  **before** Windows starts to specialize BCD which is located on the VHD.

  To do this, wait until "Windows is installing devices" message appears and

  then press `Shift+F10` to get command prompt window. Then type this:

  ```

  > C:\boot\mount.cmd

  ```

  This may take some time as the script waits until the drive actually appears

  as a volume, and keeps trying to assign it for 10 minutes. You can check

  if everything went right by reading `C:\boot\mount.log` after installation

  (and after every boot).



  If you get this message: "Windows Setup could not configure Windows to run

  on this computer's hardware", then probably you did this too late and you

  need to repeat the procedure from step 5.



  This has to be done only once during setup. Later we will configure a service

  to mount boot volume automatically at startup.



11. If setup process continues without errors then all went OK and now we need

  to configure the system to mount VHD drive at startup in order to allow it

  correctly handle BCD during updates. You may do this by installing Windows

  Resource Kit Tools (reg files in this repository assume that Windows Server

  2003 Resource Kit Tools are installed). After you install this, you may simply

  add [`bootmgr.reg`](boot/bootmgr.reg) to the registry. This will install the

  service named `bootmgr` via `srvany.exe` utility from the Resource Kit. You

  can then check if this works by starting this service and looking if the

  volume B: appears. If all is OK and B: shows in the Explorer you can check

  if BCD utilities work correctly by e.g. executing `bcdedit` without args in

  elevated command prompt and looking for output (it should dump current

  configuration and not give errors such as "store could not be opened"). If

  all is OK you can reboot now and see if the service succesfully mounts the

  boot volume at system startup.



12. Optionally you may wish to hide drive B: from the Explorer window as there

  is little benefit from it there. Simply merge [`hide.reg`](boot/hide.reg)

  into the registry and reboot (probably relogin will be sufficient).



### Installing updates



Once in a while Windows installs updates that, presumably, need to modlfy data

on a boot partition. These updates go through reboot and run at early stages of

system boot, where VHD mount service is not activated yet. As a result, such

updates may fail to install.



You may temporarily move boot partition from a VHD inside of Windows machine to

separate physical (or virtual, in case where Windows runs inside a VM) drive,

proceed with update installation, and then move boot drive back to VHD inside

Windows. Follow there steps:



1. Stop and disable `bootmgr` service, this can be done from command line with

   administrative privileges:

  ```

  > sc stop bootmgr

  > sc config bootmgr start= disabled

  ```

2. Unmount boot VHD:

  ```

  > C:\boot\unmount.cmd

  ```

3. Copy `C:\boot\bootmgr.vhd` file to some other machine.

4. Convert `bootmgr.vhd` from VHD to RAW format, this can be done with

   `qemu-img convert`:

  ```

  $ qemu-img convert -f vpc -O raw bootmgr.vhd bootmgr.raw

  ```

5. Write `bootmgr.raw` to separate physical or virtual disk and attach this

   disk to Windows machine (either VM or physical).

6. Shutdown Windows machine and make a backup.

7. Attach the disk obtained from step 5 to Windows machine and boot from it.

   You should see boot drive as a separate physical disk in a running Windows

   (use Disk Management utility since the drive may be hidden), and updates

   should install normally.

8. After installing updates, re-create boot VHD by executing

  ```

  > C:\boot\create.cmd

  ```

9. Enable `bootmgr` service back:

  ```

  > sc config bootmgr start= auto

  ```

10. Shutdown Windows machine, detach physical or virtual boot disk and start it

    back from primary drive.



### Thanks and references



1. Big thanks to **wzyboy** and his original post about boot from VHD drive

  on reboot.pro (in English: http://reboot.pro/topic/19516-hack-bootmgr-to-boot-windows-in-bios-to-gpt/page-2#entry184489)

  which gives the base idea of booting Windows from VHD with GRUB.

  90% of this code was written using his instructions.

2. SysLinux MEMDISK is described here: http://www.syslinux.org/wiki/index.php/MEMDISK

3. Microsoft's article on creating a User-Defined Service:

  https://support.microsoft.com/en-us/kb/137890

4. An article about building Custom Windows PE Image:

  https://technet.microsoft.com/en-us/library/cc709665(v=ws.10).aspx

5. GNU Parted: http://www.gnu.org/software/parted/

6. GNU GRUB: https://www.gnu.org/software/grub/