Windows 8 build 8375

6.2.8375.0.winmain_win8rc.120504-1900
	Build of Windows 8
Release name	Developer Preview 7
OS family	Windows NT
Version number	6.2
Build number	8375
Build revision	0
Architecture	x86, x64, ARMv7
Build lab	winmain_win8rc
Compiled on	2012-05-04
Expiration date
Timebomb	2013-01-15 (+256 days)
SKUs
	Core; RT (CoreARM); Pro; Enterprise
Product key
	CVWV3-RKNBX-3J7X3-H8PYK-DYDPK; 2MP7K-98NK8-WPVF3-Q2WDG-VMD98 (alt)
About dialog

Windows 8 build 8375 is the official Developer Preview 7 build of Windows 8, released to partners enrolled into the Ecosystem Engineering Access Program on 5 May 2012. The available copy of this build's Enterprise SKU was dumped from a Lenovo ThinkPad Tablet 2 engineering sample and was uploaded on 25 January 2021.

Prior to its public upload, the Core SKU of this build was accidentally pictured in a set of screenshots for the app Gaana on the Windows Store. This build shows the Microsoft Confidential watermark, but does not show the build hash at the end of the tag. A forum thread referencing this build's x64 ISO image filename was posted on the Windows Live Connect forums on 14 May 2012,^[1] and several photographs of this build's ARM version running on a NVIDIA Tegra development kit were also found on the BetaWorld Wiki.^[2] The ARM32 compile was uploaded to the aforementioned website on 4 July 2023. The full build of the ARM32 compile was uploaded on 26 October 2024.

Binaries related to this build's ARMv7 compile, particularly the Windows Store General Helper Tool used to debug AppX application installation, were found within a disk dump for Windows 8.1 build 9354 (winmain).

Similar to the unidentified December 2011 build, build 8509 and build 9200.16456 (win8_gdr_soc_intel), despite not being publicly released by Microsoft, the standard set of built-in Metro applications is included by default.

ARMv7 compile installation[edit | edit source]

QEMU installation guide:

Prerequisites[edit | edit source]

The following requirements used in order to install this build onto a virtual machine are listed below:

A copy of QEMU v6.2.0, modified for Windows RT compatibility
A version of the TianoCore EDK II firmware designed for ARM32 emulation (included above), to be placed in the QEMU installation directory under fw/QEMU_EFI_1512_driver1998.fd
One virtual hard disk image (for storing the operating system)

Precautions[edit | edit source]

The "Recovery" screen appearing after the HAL failed to load

Certain Windows 8 builds (such as 8330 (fbl_woa) or 8422 (fbl_woa)) may fail to properly load certain binaries on most startup attempts due to an emulation bug that causes the boot environment to read files incorrectly (especially the Hardware Abstraction Layer) causing an invalid checksum error, despite the files themselves being unmodified. This can be worked around by attempting to retry the startup attempt multiple times.

USB emulation is largely unstable and may result in all input devices failing to register any user inputs. To restore input, switch to the QEMU compatibility monitor (Ctrl+Alt+2) and run the following commands:

device_del kbd
device_add usb-kbd,id=kbd
device_del mice
device_add usb-tablet,id=mice

Multiple BSODs might cause "Preparing Automatic Repair" messages, an early boot error will appear afterwards.
As of 2024, builds within the 85xx-9200 range cannot be booted on QEMU because the Hardware Abstraction Layer (HAL) implementation in these builds is not compatible with the current state of emulated ARM system. This can be resolved by replacing hal.dll with the one in 8439 and disabling Driver Signing Enforcement (DSE).

Instructions[edit | edit source]

Create the needed virtual disk image through the diskpart utility by running the below script; they will be created under a directory in the C: drive named ARM8. The partitions it will contain will be respectively mounted under drive letters F and P.

create vdisk file="C:\ARM8\HDD.vhd" maximum=65536 type=expandable
select vdisk file="C:\ARM8\HDD.vhd"
attach vdisk
convert gpt
create partition efi size=100
format quick fs=fat32
assign letter=F
create partition primary
format quick fs=ntfs
assign letter=P
exit

Deploy the image and apply the generic product key from the build's installation media by invoking the following DISM commands, then add the boot files to the EFI partition:

DISM /Apply-Image /ImageFile:"X:\path\to\install.wim" /ApplyDir:P:\ /Index:1
DISM /Image:P:\ /Set-ProductKey:NFV72-RG2HG-7FTTP-8FJTB-FF848 /AcceptEula
bcdboot "P:\Windows" /s F: /f UEFI

Eject the currently attached virtual disk from the machine, then paste and run the contents of the below script onto a batch file within the QEMU installation directory, replacing YYYY-MM-DD with the build's compile date:

set MAIN="C:\ARM8\HDD.vhd"

qemu-system-arm ^
    -M virt,force_el3=true,force_psci=true,pci=false,highmem=false ^
    -cpu cortex-a15 -smp cores=4,threads=2 -m 2048 ^
    -device usb-kbd,id=kbd -device usb-tablet,id=mice ^
    -drive id=SD,if=none,file=%MAIN% -device sd-card,drive=SD ^
    -bios fw\QEMU_EFI_1512_driver1998.fd -device VGA ^
    -rtc base=YYYY-MM-DD,clock=vm ^
    --accel tcg,thread=multi

Continue installing the operating system through normal means.

Changes[edit | edit source]

This is the first available build to use the new default wallpaper seen in the official Release Preview build (originally titled Shorty), albeit with a slightly higher color temperature and saturation. The boot screen was changed from the betta fish used in the Consumer Preview to a plain black screen that simply contains the word "Windows®", and would remain up through build 8509.

Findings[edit | edit source]

As the x86 Enterprise copy of this build was dumped from an engineering sample device sourced from Lenovo, the provided image dump notably includes several development leftovers. These include calibration logs and debugging tools for the device's built-in GPS location sensor (from 5 May 2012 through 9 August 2012) as well as the needed drivers required for full functionality of the ThinkPad 2 such as chipset drivers for the Intel Atom Z2760 SoC, along with internal documentation sourced from Intel, Broadcom and Ericsson development teams.

The Windows Hardware Certification Kit from build 8523 is additionally present in the provided image, and scripts for updating the firmware included as part of hardware components found within the development kit are present in a separate user account named 8375RC. The image is set up to use a key management server from Microsoft's internal corporate network that was made available to partners.