Windows 8 build 7973 (fbl_core2_sid_data)

6.2.7973.fbl_core2_sid_data.110330-1700
Build of Windows 8
6.2.7973.fbl_core2_sid_data.110330-1700
OS family
Architecturex86, x64
Compiled2011-03-30
Timebomb2011-07-01 (+93 days)
Works in
About
Windows8-6.2.7973-core2-About.png
TCB.png TCBGallery.png

Windows 8 build 7973 (fbl_core2_sid_data) is a Milestone 3 build of Windows 8. The x64 checked/debug compile of this build was uploaded to BetaArchive on 19 September 2015[1], while the x86 free compile was uploaded on 5 June 2022.

Changes[edit | edit source]

  • There are massive updates to the Metro OOBE:
    • The flower background has been replaced by a single color with a spotlight in the middle.
    • "Express settings" debuted as "Recommended settings".
    • Options and buttons have been uplifted to better fit with the Metro design.
    • This marks the first time where the new loading spinner is used. It can be seen at the end of the OOBE.

Editions and keys[edit | edit source]

Edition / SKU Name Key
Home Basic YGFVB-QTFXQ-3H233-PTWTJ-YRYRV
Home Premium RHPQ2-RMFJH-74XYM-BH4JX-XM76F
Professional HYF8J-CVRMY-CM74G-RPHKF-PW487
Ultimate D4F6K-QK3RD-TMVMJ-BBMRX-3MBMV

Redpill[edit | edit source]

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

The Metro in this build is identical to its alternate compiles. However, MS Help has been removed.

Bugs[edit | edit source]

Aero[edit | edit source]

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.

Advanced Vector Extensions CPU bug[edit | edit source]

This build's x86 compile 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.

Aero Glass in Home Basic[edit | edit source]

This build automatically enables Aero Glass transparency even when installing the Home Basic SKUs, which is not supported by default. However, changing the color scheme (visual style) to another one and then back to the default one will disable Aero Glass.

Compiler[edit | edit source]

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.

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 A552:

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 signatures and thus requires {bootmgr} nointegritychecks to be enabled in the BCD 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]

References[edit | edit source]