UsefulAGKHelper

Please continue here in original Win-Raid discussion

XP64 SP2 + post SP2 update pack
Gigabyte B450 Aorus M
F52 BIOS AGESA 1.0.0.6 (original F41 AGESA 1.0.0.3 also worked), (booted to XP64 on a different PC with F62d, so maybe Zen3 as well?)
Ryzen Zen2 Matisse CPU

Issues
Restart does not work with XP/XP64 with any of the acpis when using a PS2 keyboard.  Have to manually push the restart button. Shutdown works fine.  Workaround, use USB keyboard after it is installed (or integrate backported USB3 driver)
BIOS
Gigabyte B450 Aorus M BIOS settings
So I noticed that by default virtualization (AMD-V) aka "SVM" was disabled by default.
BIOS > MIT > Advanced Freq Settings > Advanced CPU Settings > SVM Mode Enabled & CoolNQuiet Enabled
BIOS > MIT > XMP Profile 1
BIOS > BIOS > CSM Support Enabled & Fastboot Disabled & Full Logo Disabled
You can also enable a PPT limit on the CPU lower than default.  Lose a little bit of performance for a nice drop in heat.  
BIOS > Peripherals > AMD Overclocking > PBO to Enabled
BIOS > Peripherals > AMD CBS > Package Power Limit > Manual & ##
Picture shows a nice spot for power/performace around 50W


ACPI
ACPI needed for new motherboards.  First versions were based on longhorn 5048 with some BSODs patched.  There was a x86 version based on the original XP acpi with new instructions patched in assembly as well (6666).  Latest version for XP/XP64 (7777) is here,
https://www.mediafire.com/file/wsqgptapdrxhidf/ACPI2.0_v4_x86+x64_5.1+5.2.7z/file
 
Drivers
GPU Drivers (Tested nvidia GT710, GTX750Ti, and amd HD5450 video cards)
NVIDIA 368.81       7/10/2016
AMD 14.4           09/05/2014

Onboard LAN/Audio drivers
Realtek Audio   5.10.0.7514           8/23/2016
Realtek LAN   5.836.125.2018       1/25/2018

AMD CPU CoolNQuiet Driver 1.3.2.53       8/22/2007
Download AMD Processor Driver 1.3.2.53 and turn on power management if you want CPU to clock down during idle.

Chipset Drivers (works with native storport on XP64, for XP you will need to integrate backported storport from Advanced)

DEV7901/43C8   FCH/400 Series SATA Controller       Option1: AMD 1.2.1.321
Download an old 13.4 XP/XP64 chipset pack from AMD.  
Open up amd_sata.inf and add in these lines underneath existing DEVs (a non B450 may have different DEV_):
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_7901&CC_0106
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_7904&CC_0106
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_43C8&CC_0106[/spoiler][spoiler=DEV7901/43C8   FCH/400 Series SATA Controller       Option2: StorAhci_V1.0_20200928]Download Schtrom's StorAhci SATA AHCI Driver from sourceforge.
Pros: Universal driver.  Not limited to just AMD controllers.
Cons: Sequential speed is slower compared to AMD 1.2.1.321
Needs SMART patch on backported win7 storport to enable SMART.
DEV7901/43C8   FCH/400 Series SATA Controller       Option2: StorAhci_V1.0_20200928
Download Schtrom's StorAhci SATA AHCI Driver from sourceforge.
Pros: Universal driver.  Not limited to just AMD controllers.
Cons: Sequential speed is slower compared to AMD 1.2.1.321
Needs SMART patch on backported win7 storport to enable SMART.
NVMe           OFA NVMe 1.3 Storport Miniport       Option1: 20180719
Download Schtrom's OFA NVMe 1.3 Storport Miniport from sourceforge.
You will need to integrate a new version of storport.sys for it to work. Version 4173 (KB943545) or newer.  You can also use the postSP2 update pack.
Tested with a Samsung PM981 and storport 5.2.3790.4485.
-Version 1.3 works.  Version 1.5 stalled in the TXT setup just before format partition page.
-Use MBR for boot drive.  Native XP/XP64 does not boot from GPT.
-Use NTFS.  FAT32 starts install but hangs in the GUI setup halfway through Installing Devices.
-No SMART data from CrystalDiskInfo, SMART with HWiNFO.
DEV43D5           400 Series USB 3.1 XHCI Controller   1.0.5.3
Download the Windows 7 chipset pack for the B450 from AMD.
1.0.5.3 USB driver from USB31_PT for the controller and the hub works with the motherboard USB ports.  But you get a Code 39 error.  To fix, you will have to copy usbd.sys to your \system32\drivers folder for a live system.  You can also modify the inf file in two spots to also copy over the usbd.sys file when it copies over the driver sys file like the amdxhc31.sys or amdhub31.sys.
Use can decompress the usbd.sy_ file from your ISO or extract latest version from an unofficial service pack.  In CMD, "expand usbd.sy_"

Chipset Drivers (advanced)
NTOSKRNL Emu_Extender   required
-Download NTOSKRNL Emu_Extender from sourceforge.
https://github.com/MovAX0xDEAD/NTOSKRNL_Emu
-Follow the instructions and compile backported drivers.
THe USB driver needs Kernel Mode Driver Framework 1.11 (WDF 1.11).  
-Follow the instructions from above and create updated wdf files.

Useful Tools:
-Hexplorer or equivalent hex editor
-Dependency Walker
-PEChecksum.exe
DEV7901/43C8   FCH/400 Series SATA Controller       Option3: AMD 1.2.1.402
-Download the Windows 7 chipset pack for the B450 from AMD.  
-Open up amd_sata.inf and change the two lines that have NTAMD64.6.1 -> NTAMD64 (NTx86 if doing the 32bit version)
-Add in these lines underneath existing DEVs if not already there (non B450 board may have different DEV_):
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_7901&CC_0106
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_7904&CC_0106
%AMDSATA.DeviceDesc% = amd_sata_inst, PCI\VEN_1022&DEV_43C8&CC_0106
-Open up amd_xata.sys with hexplorer or equivalent, find and change ntoskrnl.exe -> ntoskrn8.sys.
-Apply PEChecksum.exe on amd_xata.sys
DEV149C           Matisse USB 3.0 Host Controller       usbxhci 6.2.9200.xxxxx
Backported generic Win 8 USB3 driver from NTOSKRNL_Emu works. Needs WDF1.11 backport as well.
NVMe           Generic Windows 7 NVMe           Option2: stornvme 6.1.7601.23403
Backporting Windows 7 NVMe drive works.  No SMART info.
NVME           Samsung Option3: 3.3.0.2003
Backport the Samsung NVME driver.  secnvme.sys and secnvme.sys imports need to be changed to NTOSKRN8.SYS like with the other drivers.   No SMART with CrystalDiskInfo but it does work with HWiNFO.
I only have a Samsung NVME so havent tested if the generic works with other brands.
 
Chipset Drivers (null)
DEV790B           FCH SMBus Controller             
Null driver.  Download an old 13.4 XP/XP64 chipset pack from AMD or get Windows 7 for the B450 chipset.  
Open up SMBUSamd.inf and add in these two lines underneath existing DEVs:
%AMD.DeviceDesc0% = AMDSMBus, PCI\VEN_1022&DEV_790B
%AMD.DeviceDesc0% = AMDSMBus64, PCI\VEN_1022&DEV_790B
 
DEV1481           Starship/Matisse IOMMU              
Null driver.  Download an old 13.4 XP/XP64 chipset pack from AMD or get Windows 7 for the B450 chipset.
Open up AmdIOV.inf and add in this line underneath existing DEVs:
%IOMMU.DeviceDesc%=NULL_DRIVER,PCI\VEN_1022&DEV_1481
DEV1486           Starship/Matisse Cryptographic Coprocessor PSPCPP
Install null driver to remove from missing devices.
DEV1485/148A   Starship/Matisse Reserved SPP/PCIe Dummy Function
According to the readme this should also be a null driver. Unlike the SMBus and IOMMU, this one has a sys file that tries to install.
Update inf to add DEV1485 and DEV148A.
ACPI\AMDI0030          
Install null driver to remove from missing devices
Extra Stuff
VMware and USB flash drive passthrough
When using VMware, if you connect a USB flash drive and try to pass it through to the guest OS, you will need to use a USB port that is using the generic backported USB driver in the host OS. It does not work then using the AMD USB31_PT 1.0.5.3 chipset drivers from the motherboard. From the article it looks like other motherboard specific drivers will have the same issue with a few exceptions.  Once you get the Win8 USB3 up and running, you can replace the AMD motherboard USB drivers.
https://kb.vmware.com/s/article/2041591
Tested with: XP64host with VM10.0.7(last XP version) and Win7x64host with VM10.0.7 & 15.5.6(last Win7 version).
Testing passthrough with a Kingston USB2.0 flash drive works fine. But when connecting a Kingston USB3.0 flash drive vmware gets a "unable to connect to ideal host", and the drive does not load properly in the WinXP guest OS.

VMware and USB3.0 flash drive
If you change the USB compatibility in vmware in Settings from 2.0 to 3.0, then install the backported generic drivers to the XP guest OS, it will work properly.
Note that the vm image hardware compatibility mode has to be 8 or higher, if you are using an image set to 6.5-7.x mode or lower then the USB 3.0 drop down menu will not show up.