Windows 8 build 7978

Windows 8 build 7978 is a build of Windows 8. This build was leaked to the BetaWiki Discord server on 9 May 2021. It is the last build to feature the boot screen used in Windows 7.

Redpill
Redlock can be used to unlock all of the Redpill levels on this build, including the Start screen.

The design of the Start screen tile has been changed, and as such no longer features a colored background that is based on the application's icon. A dark aqua background has been introduced in place of the previous functionality.

Bugs

 * This build will not boot on Intel CPUs with the AVX instruction set due to a bug, with a cpu triplefault immediately after the bootscreen (this can also present itself as three BSODs occurring, one after the other, with different error codes and overwriting each other on the screen). This is discussed later in the article.
 * This build must be installed on either an IDE or SATA hard drive since SCSI disk devices are not functional on this build.
 * On some devices, opening either Windows Photo Viewer or Internet Explorer results in an  bugcheck. This can usually be fixed by using the Windows Basic theme.
 * Some graphics drivers may cause only the window borders to render, as well as causing the screen to flicker whenever the mouse is moved.
 * This build incorporates a USB 3.0 driver that is incompatible with some USB controllers.

Aero
This build appears to have a slightly broken Windows Aero theme, with only the top portion of the window frame using the blur effect, leaving the side borders transparent.

Compiler
This is one of the first builds to make use of a new code compilation engine. However, the problems surrounding it at that time resulted in the build becoming unbootable on certain hardware, as the kernel does not properly function on modern Intel CPUs with the AVX instruction set and a small number of AMD CPUs. As a result, a CPU triple fault occurs resulting in either a crash on a hypervisor or a reboot on real hardware.

A majority of the bugs found in this build are a side effect of the new compiler.

VMware Workstation
The compatibility level must be set to version 7.x or lower in order to boot this build. In addition, the following block of code must be added to the VMX (virtual machine configuration) file in order to allow this build to boot on modern Intel CPUs:

featureCompat.enable = "FALSE" cpuid.0.ebx = "0110:1000:0111:0100:0111:0101:0100:0001" cpuid.0.ecx = "0100:0100:0100:1101:0100:0001:0110:0011" cpuid.0.edx = "0110:1001:0111:0100:0110:1110:0110:0101" cpuid.1.eax = "0000:0000:0000:0001:0000:0110:0111:0001"

The above configuration is mostly not required if the host machine has an AMD processor.