Windows Extra 8 build 8005 (fbl core1 kernel cptx.130419-1745)

**Windows Extra 8 build 8005 (fbl\_core1\_kernel\_cptx.130419-1745)** is a Milestone 3 build of Windows Extra 8, which was shared on June 28, 2024. This build features a new wallpaper with an updated wordoku puzzle. It was compiled 14 days earlier than the Computex 2013 build.

## Editions and keys

 Home Basic
 Home Premium
 Professional
 Ultimate

## Redpill

Continuing on with the evolution of Metro starting with build 7998, the unlocked features in this build are a middle ground between the early Milestone 2 Metro of builds 7947 to 7983 and the closer to final looks of builds 8052 and 8076. The Start screen now has the "Start" header, along with the Other Programs UI being replaced with the Applications list. The Charms bar now has a clock appear along with it, along with the Settings charm being redesigned, adding some non-functional toggles for the Power, keyboard, and a placeholder toggle called "VanUI", possibly standing for View Active Networks.

The Aero theme has also been updated to feature a flatter design, resembling the Windows Basic of this build. In this build, it is already possible to change the accent color of the start screen, however there are only two colors available. To do this, open regedit, go to `HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Accent` and create a DWORD named `ColorSet` and set its value to 1. When you logoff and logon again, the start screen will be a different blue gradient.

## Bugs

* It appears that it is possible to "uninstall" the desktop. However, clicking Uninstall does nothing.
* The Task Manager shows erratic values for the network usage.
* This build has issues installing on SCSI drives, and needs to be installed on an IDE drive.
* The boot screen has rendering issues when starting setup, showing both the loading files and boot screen at once.
* On some machines, this build may take a significant amount of time to boot.

### Advanced Vector Extensions CPU bug

This build will not boot on some CPUs with the Advanced Vector Extensions (AVX) instruction set due to a bug where a CPU triple fault occurs immediately after the boot screen is first displayed. A workaround is discussed later in the article.

## Compiler

This is one of the first builds to be compiled using a new compiler. However, the problems surrounding it at that time resulted in the build becoming unbootable on certain hardware, as the boot loader does not properly function on modern x86 CPUs, namely Intel processors with the AVX instruction set and a select 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.

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

### Patching winload.exe to run on Intel processors with AVX

In order to properly enable SSE instructions for machines using Intel processor with AVX, the 9th bit in Control Register 4 (CR4) must be turned on. The following code is executed and is located in winload.exe at offset A137:

```
mov eax, cr4 ; 0f20e0
or eax, 20h ; 83c820 -- Turn on 5th bit, PAE (Physical Address Extension)
mov cr4, eax ; 0f22e0 -- Store it in CR4
mov eax, cr0 ; 0f20c0
or eax, 80000000h ; 0d00000080 -- Enable paging
mov cr0, eax ; 0f22c0

```

By default the following bits are set in CR0: Protected Mode (PE) (0x00000001), Monitor co-processor (MP) (0x00000002) and Extension type (ET) (0x00000010), with no bits in CR4 set initially, so the need to turn on the 9th SSE bit (i.e. OR with 0x600) should be done, but due to limitation in this piece of code, a rewriting needs to be done and the following approach may be used instead:

```
mov eax,620h ; b820060000
mov cr4,eax ; 0f22e0
mov eax,80000013h ; b813000080
mov cr0,eax ; 0f22c0
nop ; 90
nop ; 90
nop ; 90
nop ; 90

```

As a disclaimer, patching winload.exe with these changes will invalidate integrity checks and thus requires Test Mode to be enabled (by setting `NoIntegrityChecks` in the BCD to on) in order to boot with the patched winload.exe, as well as ownership of the file in both `%systemroot%\System32` and `%systemroot%\System32\Boot` need to be altered in case file replacement was not possible.

### Compatibility

#### VMware Workstation

For another workaround on the Intel SSE bug that does not involve patching and disabling security checks, the compatibility level must be set to version 8.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:

```
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, and as such only requires the compatibility version to be changed.