readme.loader.txt

     This file describes the Grub2Win boot process.

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The Windows bootmanager / BCD loads C:\grub2\winloader\grub2.boot which then takes over control.

Now grub2.boot searches all disk drives for itself in order to find the disk address where the grub base directory is installed.
This must be the Windows boot drive.

grub.boot then sets variable $winpart to point to the Windows boot drive.
$winpart usually has a value of (hd0,msdos1) unless you are booting Windows from another drive or partition.

Variable $winpart is used as a handy way to boot Windows or Invaders from grub2.
Windows 8 may need to boot from a special ?System Reserved? partition.

Likewise, variable $prefix is set by grub.boot and usually has a value of (hd0,msdos1)/grub2

The $prefix variable is required by grub2 to locate its base directory and files.
If $prefix is not set properly, grub2 initializes in rescue mode (limited command line).

grub2.boot then dynamically loads several other modules to support various partition and filesystem types.

Then C:\grub2\grub.cfg is read and used to build the grub2 boot menu display.

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For Windows XP and Windows 2000:

boot.ini points to C:\grub2\winloader\xpstage1.img whose only job is to load C:\g2ldr.
When grub2win was installed, C:\g2ldr was created.

xpstage1.img has very limited capabilities and can only find C:\g2ldr in the root of a partition, not a directory.

g2ldr takes control and searches all disk drives for C:\grub2\winloader\grub2.boot in order to find the disk address where the grub base directory is installed.

The rest of the boot process is identical to Windows 8, Windows 7 and Vista.


Note: The aging XP / 2000 bootloader does not work reliably when loading grub.boot directly.
This is why xpstage1.img is used instead.
XP / 2000 works best in character mode. Graphics sometimes cause lockups and inconsistent behavior.


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