Windows 8 build 7985 (fbl_core1_kernel_cptx.110419-1745)

Build of Windows 8
OS familyWindows NT
Version number6.2
Build number7985
Build revision0
Build labfbl_core1_kernel_cptx
Compiled on2011-04-19
Expiration date
Timebomb2012-03-15 (+331 days)
About dialog

Windows 8 build 7985 (fbl_core1_kernel_cptx.110419-1745) is a Milestone 3 build of Windows 8. The x86 installation media for this build was first shared on 28 June 2022, followed by its public debugging symbols the next day.

It was compiled 14 days earlier than the Computex 2011 demo build.

Editions and keys[edit | edit source]

Edition / SKU Key
Starter 7Q28W-FT9PC-CMMYT-WHMY2-89M6G
Home Premium RHPQ2-RMFJH-74XYM-BH4JX-XM76F
Professional HYF8J-CVRMY-CM74G-RPHKF-PW487

Changes[edit | edit source]

User interface[edit | edit source]

Redpill-specific changes[edit | edit source]

Continuing on with the evolution of Metro starting with build 7978, the unlocked features in this build are a middle ground between the early Milestone 2 Metro of builds 7927 to 7963 and the closer to final looks of builds 8032 and 8056.

The main Start screen user interface now includes a label for specific pages, and the Other Programs page has been replaced with a new Applications list, which displays the user's installed applications. The Charms bar now brings up a dedicated clock, and the Settings charm was redesigned to include new (albeit non-functional) option buttons for power, keyboard layout settings, and active network connections.

The Aero theme has also been updated to feature a new design with sharp window corners and flat buttons, making it more resemblant towards the final look of the Windows 8 user interface. The ability to modify the Start screen's accent has been implemented, although its functionality is only available through the use of a registry hack and is largely limited to only two specific color choices. To change the start screen's accent color to a dark blue, merge the following entry into the current user's registry hive:


Miscellaneous[edit | edit source]

Bugfixes[edit | edit source]

Desktop Window Manager[edit | edit source]

The Windows Aero visual style's atlas no longer breaks when attempting to composite blur, and glow effects on caption bar text now renders properly.

Bugs and quirks[edit | edit source]

App tiles[edit | edit source]

Some app names (such as Control Panel, Chess Titans, Defragment and Optimize Drives, etc) may be truncated by normal sized tiles.

Networking bug[edit | edit source]

Enabling networking in hypervisors will cause a 0x133 BSOD.

Advanced Vector Extensions CPU bug[edit | edit source]

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. This is the last build to contain this bug.

This problem can also present itself as three bugchecks occurring one after the other, with different error codes overwriting each other on the screen.

Start screen[edit | edit source]

The desktop application tile is treated as if were a native Metro application despite it not being one. As a result, it is possible to "uninstall" the desktop, although nothing will happen if attempted.

Windows Setup[edit | edit source]

  • This build must be installed on either an IDE or a SATA hard drive as SCSI disk devices will not be detected properly.
  • On some machines, this build may take a significant amount of time to boot.

Boot manager[edit | edit source]

As the kernel/boot loader does not call any code to clear the video buffer early within the boot process, any graphics that are displayed in the boot screen may overlay themselves on top of the last frame sent by the boot manager. This problem is easily observed when loading into a ramdisk boot image or while loading into setup.

Taskbar[edit | edit source]

The Your Look tile has a white trail in the left and white instead of left white up and down.

DWM[edit | edit source]

If DWM is restarted when Redpill is enabled, it causes the Start Screen to glitch while dragging/scrolling.

General[edit | edit source]

Attempting to restart or shutdown in this build will cause a softlock on VMware Workstation versions 15.x and newer releases. It is generally recommended to force an ACPI shutdown by powering off or resetting the virtual machine from the Power drop-down menu.

Logoff error[edit | edit source]

Sometimes, "WinRT UI Window" will prevent the user from logging off.

Compiler[edit | edit source]

This is one of the first builds to be produced 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.

Patching winload.exe to run on Intel processors with AVX[edit | edit source]

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[edit | edit source]

VMware Workstation[edit | edit source]

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 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:

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.

Gallery[edit | edit source]