Windows 8 build 7973 (fbl_core2_sid_data)

6.2.7973.0.fbl_core2_sid_data.110330-1700
	Build of Windows 8
OS family	Windows NT
Version number	6.2
Build number	7973
Build revision	0
Architecture	x86, x64
Build lab	fbl_core2_sid_data
Compiled on	2011-03-30
Expiration date
Timebomb	2011-07-01 (+93 days)
About dialog

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.

Editions and keys[edit | edit source]

Edition / SKU	Key
Starter ^[a]	7Q28W-FT9PC-CMMYT-WHMY2-89M6G
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]

The Metro user interface is visually identical to the fbl_core1_kernel_npc and fbl_dnt3_wireless compiles of this build. However, the MS Help app is not included.

Out-of-box experience[edit | edit source]

There are massive updates to the Metro OOBE:

The fish background has been replaced by a single color with a spotlight in the middle.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, which can be seen at the end of the OOBE.

Bugs and quirks[edit | edit source]

Advanced Vector Extensions CPU bug[edit | edit source]

The x86 compile of 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.

Aero[edit | edit source]

Only the top portion of the window frame is blurred when using the Windows Aero and Aero Lite theme, leaving the side borders transparent.

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 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]

The Intel SSE bug can be worked around by setting the compatibility level to version 7.x or lower and 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.