• Motherboard: Gigabyte z170x-Gaming 7 rev. 1.0
• BIOS Version: F22m
• GPU: Radeon RX6800

Easily managed to set it up and get it running.
After some quick testing I found out that...

1gb = According to Radeon drivers (ver22.10.2) and GPU-Z, ReBAR gets enabled, works as expected.
2gb = Halts on bootlogo, unable to enter bios. Need to reset bios.
4gb+ = Boots into Windows but unable to see bootlogo during boot and unable to enter bios, trying to enter bios using the Windows troubleshooting menu also fails. (tested up to 16gb with the same behavior)

Did some benchmarks on 4gb and 16gb to test for system instability, all seemed fine except that I was unable to see the bootlogo on boot or access the bios which can be confusing because during the whole booting process it does seem like the computer has failed to post.

Greetings,

My system specifications are Gigabyte Aorus Gaming K3, rx470 8gb, i5 8600k.

A few years ago, the motherboard got update from Gigabyte with 4g decoding rebar support, which was working fine at that time. However, with the release of new AMD drivers, this feature got disabled, and my GPU became unsupported.

I came across your tutorial, but I missed some steps while flashing the BIOS as I wanted to avoid any potential risks of damaging it. Instead, I opted for the .exe tool to increase the capacity to 8192mb (13), which allowed the bar to show up in GPU-Z. Then, I used a .reg file to enable it in the AMD software.

I am now seeking your assistance in verifying whether this solution is working as expected.

If it is indeed functioning correctly, could you kindly update your wiki to reflect this so that other users can follow only the last step of the tutorial without the fear of damaging their BIOS?

I appreciate the work you have done on this project.

Best regards.

System

• Motherboard: MSI z270-A Pro
• BIOS Version: 1.60
• GPU: RTX 3080
• [Y] CSM is turned off
• [Y] 4G decoding is enabled
• [N] UEFIPatch is applied (see README for more information)

Description

Using UEFITool I searched for the PciBus string (text/unicode) and got several results, of which I am not sure which one is the correct one.

The tutorial mentions "insert the FFS module at the end of the volume".

In that part of the BIOS it says "section", there are also "files", but that part is not a volume...

The original BIOS file is this one

Can you help me find the right place to insert the module?

I have seen that there are other users with MSI z270 and ASUS z270, so I guess it could be possible to insert it correctly and make it work.

TIA

System

• Motherboard: ga-z97x Gaming5
• BIOS Version: F7
• GPU: RX 580
  

So i managed to mod bios and flash but i can only have 1024mb.. if i go 2gb or 4 or 8 my pc wont boot.. is there any fix or im stuck with 1gb?

I did the following:

git clone https://github.com/tianocore/edk2.git
cd edk2
git clone https://github.com/xCuri0/ReBarUEFI.git
cd ReBarUEFI/ReBarDxe
python3 buildffs.py

Traceback (most recent call last):
  File "/home/gandalf/src/edk2/ReBarUEFI/ReBarDxe/buildffs.py", line 18, in <module>
    subprocess.run(["build", "--platform=ReBarUEFI/ReBarDxe/ReBar.dsc"], shell=shell, env=os.environ, stderr=sys.stderr, stdout=sys.stdout)
  File "/usr/lib/python3.10/subprocess.py", line 501, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/usr/lib/python3.10/subprocess.py", line 969, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.10/subprocess.py", line 1845, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'build'

System

• Motherboard: Asus B85-Plus
• BIOS Version: Both 2304 and 2305 tried
• GPU: RX 5700
• [ √ ] CSM is turned off
• [ √ ] 4G decoding is enabled
• [ √ ] UEFIPatch is applied (see README for more information)

Description

Describe the issue here.
In Asus's bios, it uses "Memory Remap" as the "4GB decoding" in other motherboard.
Manual:
https://dlcdnets.asus.com/pub/ASUS/mb/LGA1150/B85-PLUS/E7928_B85-PLUS.pdf
In the 2.6.4 section, and it is enabled always, even you reset the bios.

As the wiki,
I inserted both the "NvmExpressDxe_5.ffs" and "ReBarDxe.ffs" to the 2304 or 2305 bios (extracted with UEFITool 0.28.0) ,
patched with UEFIPatch (but it seems only the "PciBus | Remove <16GB BAR size limit (Ivy Bridge/Haswell)" patched),
i have got that my Pci Bus range ends at 000DFFF, when i try to patch the DSDT, but there is no CreateQWordField in my "DSDT.dsl", so this is different to the wikis,
finally i flash the "unmodded DSDT bios" with AFUWINx64 (with /GAN) and it succeced, but it seems the "Above 4G decoding" didn't work, even in the original asus bios,
i am not sure if it is a bug to this motherboard's bios.

EDIT:

Working Rebar with Unlimited Size.

Notice:

MAKE THE BIOS BACKUP FIRST

• I would not recommend using afuwin to flash the uefi, my recommendation is clearly to use afuwin only for uefi backup.
• Flashing with the BIOS-FLASHBACK from the mainboard is easy and safe.
• Alternatively, you can flash the bioschip directly using a flasher, but this requires extra hardware and a second computer.

Tools:

• MMtool
• uefitool
• uefipatch
• bios file

ready to use efi Downloads:

X99-A-II-ASUS-2101_CAP_STOCKROM_64-bit_BAR_ENABLED_rebar_driver_injected_barsize_Patched.zip

X99-A-II-ASUS-2101_ROM_STOCKROM_64-bit_BAR_ENABLED_rebar_driver_injected_barsize_Patched.zip

If You want to diy

###How To:

1

• Download Latest Bios From Asus website
• download MMtool, Uefi tool and uefipatch
• download patches.txt
• patches_txt.zip
• download rebardxe.ffs and pcibus.ffs
• X99-A-II-ASUS-2101_pciebusffs_rebardxeffs.zip
• put all files in same directory

MAKE THE BIOS BACKUP FIRST

2

• Open Mmtool,
  • load Image -> ASUS_BIOS.CAP
  • Replace Tab
  • scroll down until you find "Priebus" in Volume 02
  • click on pciebus
  • look for "Module file" further up the window
  • now choose the pcibus.ffs by clicking on BROWSE
  • click replace

2b

• switch to Insert Tab
• look for "Module file" further up the window
• now choose the rebar.ffs by clicking on BROWSE
• directly below, enter "02" at Vol. index
• click insert

2c

• click "save Image"
• close mmtool

3

• download the atached patches.txt

OR

-create a new txt file in you folder

• paste
  #NVRAM whitelist unlock
  54B070F3-9EB8-47CC-ADAF-39029C853CBB 10 P:0F84B300000041F6:90E9B300000041F6_
• replace the _ at the ende ( 1f6_) with a "Space "
• save file and close it.

4

• press Win+R on your Keyboard
• or start and search for cmd
• change directory to your folder
• then type: uefipatch BIOSFILENAME.CAP -o PATCHED_BIOS_FILENAME.CAP
• press enter

5

A:

• flash that cap file using the bios flashback feature

OR

B:

• open Efitool, load Patched .cap File
• Click -> Action -> Capsule -> Extract body -> save as .bin or .rom
• flash to bios

System

• Motherboard: Asus X99A-2 (X99-A II)
• BIOS Version: 2101 (type: UEFI)
• GPU: PowerColor AMD Radeon RX 6950 XT
• Operating System: Windows 10 Pro 64-bit (10.0, Build 19045) (19041.vb_release.191206-1406)

System

• Motherboard: ASUS Z170-WS
• BIOS Version: 3062
• GPU: RTX 3080 Ti FE

Description
The ReBAR module has been placed in the correct volume, it was extracted and replaced per instructions for "ASUS no boot after patching" but with the same failing result, the script appears to be working but only with 512MB, 1024MB and higher always results in the system completing POST checks but nothing more, no display or response, CSM disabled and above 4G Decode enabled but Resizable BAR enabled in BIOS also says No

Z170WS_test.zip

System

• Motherboard: Asrock x99 Extreme4
• BIOS Version: P3.80
• GPU: RTX 3070 Gigabite OC
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)

After flashing bios with rebar.ffs and DSDT patch gpu-z showing 'Resizable BAR enabled in BIOS No'.
I was flashing it using aufwin 4.0 becouse version 5.0 only destroy my bios
I have tried other bios with the same error. Any ideas what to do next?

System

• Motherboard: x99z v102
• BIOS Version:
• GPU: 蓝宝石 RADEON RX 5600 XT 6G D6 白金版PRO OC
• CPU: E5-2667v4
• SYSTEM: Windows10 22H2
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)

Description

(My English is not very good, so I use a translator)

What I have done?

1. Adding FFS module and Writing bios(I used freedos to write bios, but the screen did not display, I used the keyboard to type directly, then restarted the computer, the bios options were reset, I guess the write is successful)
2. I have restarted the computer several times, but I still can't find the option in the bios (I try to find Advanced-PCI Subsystem Settings-Above 4G Decoding) (Repeated restarts are also to verify that the bios is not damaged).
3. Because I saw in this video that csm is turned on, as long as they all select uefi, I did not close csm as in the video.My system and graphics card are all uefi booted, and uefi is also checked in gpuz.
4. I ran ReBarState.exe on the system, just like in the video link above, type 32 and press Enter. (Running the program failed before writing to the bios. This time the program is displayed as successful)
5. I reboot the computer

Current situation
When I press the power button, all the fans are spinning, but the screen doesn't respond

1. There is no problem with the power supply, memory, cpu
2. I found my spare graphics card, gt610 (This card is not damaged, because I checked it the day before yesterday), and plugged it in. But it still doesn't show.
3. I unplugged all the hard drives and still couldn't display the bios.
4. I made a pe system with uefi boot and plugged it in, but it still didn't boot
5. I pulled out the battery from the motherboard and tried to reset the bios, but it still didn't work
6. The remote desktop is enabled on my system, but I cannot connect to it, and I cannot see the device in the router system. I think I have not entered the windows10 system

My question : What I should do next to save my computer?

Thank you for reading the issue
(I can upload the original bios file if needed)

System

• Motherboard: ASUS Z10PA-D8

• BIOS Version: Z10PA-D8-ASUS-3801 (https://disk.yandex.ru/d/46p8AXX9CawTVw)

• Modded BIOS: (https://disk.yandex.ru/d/uA7qCh1AiP-fxw)

• GPU: Gainward RTX 3070 Phantom

• [ Y] CSM is turned off

• [Y ] 4G decoding is enabled

• [Y ] UEFIPatch is applied (see README for more information)

1. I update VGA driver for GPU
2. I get original firmware
3. I turn on 4G and turn of CSM
4. I add ReBarDxe.ffs in firmware
5. I insert patch by UEFIPatch_0.28.0_win32
6. I install firmawe and reboot
7. I reconfigure bios and reboot
8. I run ReBarState.exe, set 32 and tried to reboot.
9. PC doesn't start. If I install back original bios - it boot, if I install patched bios - it boot. But after this app - it doesn't boot.

BIOS POST Code: 87

Pls, help me. I will give you all info you want.

P.S. I have programmator - so I can flash bios)

System

• Asus Rampage IV Extreme:
• BIOS Version:4901
• AMD Radeon RX Vega 64
• [Y] CSM is turned off
• [N] 4G decoding is enabled

I cant find 4G decoding in my bios.
Propablyt it is hidden.. but i lost when i trying this guide "Enabling hidden 4G decoding"
What can i do?

System

• Motherboard: Asus z170-a
• BIOS Version: 3802 (https://www.asus.com/us/supportonly/z170a/helpdesk_bios/)
• GPU: Intel Arc a750 8GB
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)

Description

Hi,
I saw that some users where able to mod the BIOS but i'm stuck on early stages: I can't even find the correct place where to put the FFS module.

Can you please help me finding where to place it?
Can I then flash the BIOS using the flash tool inside the BIOS itself?
Thank you very much in advance, you are making a very great job!!!

not a bug but a question. i have a motherboard ROG strix x299-E, a i7-7740x cpu and rtx 3070 FE. My gpu and motherboard support resizable bar tho according to intel, it seems that my cpu isn't supported. However, when I enable resizable bar in my bios, nvidia control panel and GPU-z reports resizable bar as enabled. So is cpu support really is needed or not? and if cpu supported is needed, do i need to use the ReBarUEFI too to fix it?

enabled 1GB rebar. thanks

System

• Motherboard: Asus X99A II
• BIOS Version:2101
• GPU: 6600xt
• [ ✓ ] CSM is turned off
• [ ✓ ] 4G decoding is enabled
• [ ✓ ] UEFIPatch is applied BAR size tested 8GB

Description
First of all thanks to xCuri0 for enabling Resizable BAR on my old motherboard !!!

(I didn't use opencore to boot win10)

I successfully modified the bios and it works fine in win10.（follow the instructions exactly）
I think pcibus patch caused the hackintosh boot fail, But x99aii must use the pcibus patch to successfully enable resizable bar.
If i don't use pcibus patch, Enabling resizable bar will result in a black screen (Using USB Flashback can let CMOS reset) and disabling resizable bar can successfully boot macOS&win10.

# PciBus | Don't downgrade 64-bit BARs to 32-bit (by @Mak3rde)
3C1DE39F-D207-408A-AACC-731CFB7F1DD7 10 P:C70605000000833E067506C70604000000BE01000000:909090909090833E067506909090909090BE01000000

Please help me, can this problem be solved by changing the config.plist of opencore or in other ways?

Screenshot of hackintosh use modified bios.

Modified bios files
bios.zip

Apologies if I'm missing something obvious.
I'm trying to apply the DSDT patch https://github.com/xCuri0/ReBarUEFI/wiki/DSDT-Patching#dsdt-broken-4g-decoding-fix-haswell-and-up to my Asrock Z97 Extreme 3 on BIOS 2.10: https://www.asrock.com/mb/intel/z97%20extreme3/#BIOS
However, even with all of the _OSI methods removed, my DSDT mod is significantly larger than the original, almost 700 bytes larger using iasl from ACPICA 20221020. This is leading to the error PE32 has .ROM but not DYNAMIC_BASE set -> Unpatchable atm.. from AmiBoardInfoTool.
Any ideas if there's any other parts that are safe to remove, or any other way to fix this?

dsdt.zip

Do you have a step by step guide on how to go about it?

I am having issues trying to setup the edk2 environment, seems like one of the modules is missing (at least following this guide: https://github.com/tianocore/tianocore.github.io/wiki/Common-instructions).

Or do I have to try a specific release of edk2?

I am running Ubuntu 22.04 as I am trying to get the new Intel Arc GPUs running which seems to require ReBar.

Thanks in advance.

System

• Motherboard: Asus Z97i-Plus
• BIOS Version: 2704
• GPU: Intel Arc A750 LE (supports up to 8GB BAR)
• Above 4G decoding is enabled in BIOS
• CSM is disabled
• Applied PciBus | Remove <16GB BAR size limit patch
• replaced NvramSmi module from an older BIOS(version 2103) to allow new uefi variable creation

Description
I modded the BIOS to enable rebar using your instructions but the maximum working BAR size is 1GB. At 2GB the system gets stuck during post, at 4GB and 8GB it boots into the OS(Windows 10 and Ubuntu 20.04) but video output works only from the iGPU.

This is dmesg after booting with 8GB

[    0.194347] pci_bus 0000:00: root bus resource [bus 00-3e]
[    0.194349] pci_bus 0000:00: root bus resource [io  0x0000-0x0cf7 window]
[    0.194350] pci_bus 0000:00: root bus resource [io  0x0d00-0xffff window]
[    0.194352] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000dffff window]
[    0.194353] pci_bus 0000:00: root bus resource [mem 0xdf200000-0xfeafffff window]
[    0.194354] pci_bus 0000:00: root bus resource [mem 0x800000000-0xfbfffffff window]
[    0.197052] pci 0000:00:01.0: PCI bridge to [bus 01-04]
[    0.197055] pci 0000:00:01.0:   bridge window [mem 0xf7c00000-0xf7cfffff]
[    0.197058] pci 0000:00:01.0:   bridge window [mem 0xf0000000-0xf07fffff 64bit pref]
[    0.197408] pci 0000:01:00.0: PCI bridge to [bus 02-04]
[    0.197413] pci 0000:01:00.0:   bridge window [mem 0xf7c00000-0xf7cfffff]
[    0.197453] pci 0000:03:00.0: [8086:56a1] type 00 class 0x030000
[    0.197468] pci 0000:03:00.0: reg 0x10: [mem 0x00000000-0x00ffffff 64bit]
[    0.197477] pci 0000:03:00.0: reg 0x18: [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.197491] pci 0000:03:00.0: reg 0x30: [mem 0x00000000-0x001fffff pref]
[    0.197563] pci 0000:03:00.0: PME# supported from D0 D3hot
[    0.209169] pnp 00:00: disabling [mem 0xfed40000-0xfed44fff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209785] pnp 00:06: disabling [mem 0xfed1c000-0xfed1ffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209788] pnp 00:06: disabling [mem 0xfed10000-0xfed17fff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209790] pnp 00:06: disabling [mem 0xfed18000-0xfed18fff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209791] pnp 00:06: disabling [mem 0xfed19000-0xfed19fff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209793] pnp 00:06: disabling [mem 0xf8000000-0xfbffffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209794] pnp 00:06: disabling [mem 0xfed20000-0xfed3ffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209796] pnp 00:06: disabling [mem 0xfed90000-0xfed93fff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209797] pnp 00:06: disabling [mem 0xfed45000-0xfed8ffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209798] pnp 00:06: disabling [mem 0xff000000-0xffffffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209800] pnp 00:06: disabling [mem 0xfee00000-0xfeefffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209801] pnp 00:06: disabling [mem 0xf7fe0000-0xf7feffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.209803] pnp 00:06: disabling [mem 0xf7ff0000-0xf7ffffff] because it overlaps 0000:03:00.0 BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
[    0.217718] pci 0000:01:00.0: BAR 15: no space for [mem size 0x200000000 64bit pref]
[    0.217720] pci 0000:01:00.0: BAR 15: failed to assign [mem size 0x200000000 64bit pref]
[    0.217723] pci 0000:02:01.0: BAR 15: no space for [mem size 0x200000000 64bit pref]
[    0.217724] pci 0000:02:01.0: BAR 15: failed to assign [mem size 0x200000000 64bit pref]
[    0.217725] pci 0000:02:01.0: BAR 14: no space for [mem size 0x01800000]
[    0.217726] pci 0000:02:01.0: BAR 14: failed to assign [mem size 0x01800000]
[    0.217727] pci 0000:03:00.0: BAR 2: no space for [mem size 0x200000000 64bit pref]
[    0.217729] pci 0000:03:00.0: BAR 2: failed to assign [mem size 0x200000000 64bit pref]
[    0.217730] pci 0000:03:00.0: BAR 0: no space for [mem size 0x01000000 64bit]
[    0.217731] pci 0000:03:00.0: BAR 0: failed to assign [mem size 0x01000000 64bit]
[    0.217732] pci 0000:03:00.0: BAR 6: no space for [mem size 0x00200000 pref]
[    0.217733] pci 0000:03:00.0: BAR 6: failed to assign [mem size 0x00200000 pref]
[    0.217734] pci 0000:02:01.0: PCI bridge to [bus 03]
[    0.217744] pci 0000:02:04.0: PCI bridge to [bus 04]
[    0.217748] pci 0000:02:04.0:   bridge window [mem 0xf7c00000-0xf7cfffff]
[    0.217756] pci 0000:01:00.0: PCI bridge to [bus 02-04]
[    0.217759] pci 0000:01:00.0:   bridge window [mem 0xf7c00000-0xf7cfffff]
[    0.217764] pci 0000:00:01.0: PCI bridge to [bus 01-04]
[    0.217766] pci 0000:00:01.0:   bridge window [mem 0xf7c00000-0xf7cfffff]
[    0.217768] pci 0000:00:01.0:   bridge window [mem 0xf0000000-0xf07fffff 64bit pref]
[    0.217771] pci 0000:00:1c.0: PCI bridge to [bus 05]
[    0.217779] pci_bus 0000:00: Some PCI device resources are unassigned, try booting with pci=realloc
[    0.217780] pci_bus 0000:00: resource 4 [io  0x0000-0x0cf7 window]
[    0.217782] pci_bus 0000:00: resource 5 [io  0x0d00-0xffff window]
[    0.217783] pci_bus 0000:00: resource 6 [mem 0x000a0000-0x000dffff window]
[    0.217784] pci_bus 0000:00: resource 7 [mem 0xdf200000-0xfeafffff window]
[    0.217785] pci_bus 0000:00: resource 8 [mem 0x800000000-0xfbfffffff window]
[    0.217786] pci_bus 0000:01: resource 1 [mem 0xf7c00000-0xf7cfffff]
[    0.217787] pci_bus 0000:01: resource 2 [mem 0xf0000000-0xf07fffff 64bit pref]
[    0.217788] pci_bus 0000:02: resource 1 [mem 0xf7c00000-0xf7cfffff]
[    0.217789] pci_bus 0000:04: resource 1 [mem 0xf7c00000-0xf7cfffff]

00:00.0 Host bridge: Intel Corporation 4th Gen Core Processor DRAM Controller (rev 06)
03:00.0 VGA compatible controller: Intel Corporation Device 56a1 (rev 08)
06:00.0 Network controller: Broadcom Inc. and subsidiaries BCM4352 802.11ac Wireless Network Adapter (rev 03)

and /proc/iomem

f0000000-f07fffff : PCI Bus 0000:01
  f0000000-f07fffff : 0000:01:00.0
f7400000-f77fffff : 0000:00:02.0
f7800000-f7afffff : PCI Bus 0000:06
  f7800000-f79fffff : 0000:06:00.0
  f7a00000-f7a07fff : 0000:06:00.0
f7b00000-f7bfffff : PCI Bus 0000:01
  f7b00000-f7bfffff : PCI Bus 0000:02
    f7b00000-f7bfffff : PCI Bus 0000:04
      f7b00000-f7b03fff : 0000:04:00.0
...
100000000-41fdfffff : System RAM
  179e00000-17ae025c7 : Kernel code
  17b000000-17ba87fff : Kernel rodata
  17bc00000-17c0455ff : Kernel data
  17c393000-17c9fffff : Kernel bss
41fe00000-41fffffff : RAM buffer

Great project, but i want to ask if it is possible to apply the patches for laptop bioses like asus n550jk-gtx850m or lenovo y520-gtx1060?

System

• Motherboard: Asus Z270-A
• CPU: i7700K
• BIOS Version: 1302
• GPU: Intel ARC380
• CSM is turned off
• 4G decoding is enabled
• [N] UEFIPatch is applied (see README for more information)

Description
I modded the BIOS and flashed it via Asus AI Suite (all the other methods didn't work).
PC posts properly, however after running ReBarState.exe and rebooting into GPU-Z ReBar status is still disabled.

Are there some further checks I may do?

1. I'd like to know if new BIOS has really been flashed properly (I've got no errors, however I can't be sure)
2. Something else?

Thanks for help

PRIME-Z270-A-ASUS-1302-ReBar.zip

System

• Motherboard: ASUS Z270 Mark 1
• BIOS Version: 1501
• GPU: GIGABYTE RTX 3070 Ti
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)
  TUF-Z270-MARK-1-ASUS-1501.zip

Description

hello, I am trying to mod my bios looking for PciBus into UefiTool but I didn't find any Hex line, I used MMtool also but I didn't find anything. Does somebody help?

I have attached the zip file of the motherboard

Thank you

Hi,

I'm wondering if it's possible to inject the driver using a bootloader like Clover, OpenCore or DUET.
OEM systems usually have some sort of module that disables any BIOS mods by recognizing modifications and refusing to POST with some sort of checksum error (they usually have beep codes for that).

I feel like the real strength of your mod are budget OEM systems, Chinese X99 where you mod the BIOS anyway and maybe LGA 1151 mutants like the QTJ2 that already require a BIOS mod to make Coffee Lake mobile processors work on Skylake/Kaby Lake boards.

What I'm trying to figure out is if there's a way to serve the one budget group that seems less easy. I know in the past people have used bootloaders to get around older BIOSes not supporting boot from PCIe because they can't mod the BIOS itself. I'd appreciate any info you have.

Currently don't have any OEM system on hand to test this, but a B350 one that doesn't have a BIOS update with ReBar that I could test any suggestions. I think it could be valuable info added to your documentation as well.

System

• Motherboard: Z77X-D3H
• BIOS Version: F18i
• GPU: GTX 1070

Description
Patching the bios MMIO causes Windows to hang on boot screen and will not proceed to login screen. Seen that it might need DSDT mod, any more info that?

Sorry for bothering you.

Hi @xCuri0,

First of all - great effort. Stumbled upon your post on reddit.

I glanced over the source code before building just to check if there's nothing super malicious there. Frankly, I don't have enough EFI knowledge to judge but the C code looked sane, so I went on to build the module all singing and dancing based on the promise of Ivy Bridge + readied myself for a treat.
I've built the ffs (you gotta love that extension) and when I fired up the MMTool it struck me that on X79/C602 chipset BIOSes - that is Ivy Bridge E/EP (high end 4th gen i7s and Xeons v1/v2) - there's no PciHostBridge. There's PciRootBridge.

Now, seeing that you've got hooks to PciHostBridge I decided not to flash it as I guess it would be pointless to try in this instance.

Effectively I'm trying to enable Nvidia Tesla M40 24GB on a Supermicro X9 server motherboard - I have a couple of those boards and I'm lead to believe some support ReBAR and some not. Some basically were certified to run with 24GB K80s, so there's no other option for such a memory hog to run without ReBAR.
From newer systems - I'm certain that M40 requires ReBAR/CSM disabled/full blown UEFI to work.
On this particular X9DRI-F (that is not GPGPU enabled), the card is detected but lspci -vvv shows all memory regions as disabled, nvidia kernel modules fail to load and all of that sadness associated with it.

On top of that I also have a couple of old X79 boards and double checked their BIOSes and it's a similar story to C602 server chipset.
Here's the screenshot, it presents the modules in GA-X79-UD3, Supermicro X9DRI-F and for comparison, the BIOS for the board you mentioned in your reddit post GA-B75M.

BTW. This supermicro board has a MMIOH of up to 1T, only mentioning it because on reddit I think you mentioned Ivy goes only up to 64G, I'm sure you meant consumer boards; But just mentioning this for completeness.

All in all, I think it would be fair to change the description in this repo to ivy bridge instead of ivy bridge+. The + may suggest anything above Ivy Bridge, but E/EP are above and there's this clash in the module names.

I'd love to provide you with a patch but my EFI knowledge doesn't go that deep unfortunately.

System

Laptop MSI Prestige 15 A10SC:

• BIOS Version: E16S3IMS.108
• GPU: GTX 1650 Max Q / Mobile

Description

I can't patch my BIOS file after including the ReBarDxe module. Is there anything else I can do?

In UEFIPatch's folder there were two .txt files, "patches.txt" and "patches-misc.txt". I deleted them and only kept the file with the patches the guide explicits: https://github.com/xCuri0/ReBarUEFI/blob/master/UEFIPatch/patches.txt

Motherboard: ASRock z-170 k4/d3
GPU: 6700xt
CPU: 8700k
I can't open the "above 4g decoding" or "above 4g mmio bios assignment"

when I turn this to enable ,it can't work, can't into windows system ，because bios can not find any sata drives

then when i try to use modGRUBShell.efi
setup_var 0x3 0x0
reboot
setup_var 0x3 0x1
but there is nothing happend

It makes me very depressed. Can you give me some suggestions

Originally posted by @jnyk in #11 (comment)

MOBO: Gigabyte Z97X-Gaming 3
BIOS: F8e (not available on GB page, i got it from Support. This bios add TPM 2.0)
CPU: Intel Xeon E3-1285L v4
GPU: RX 6900XT
CSM disabled, SecureBoot enabled, TPM 2.0 Enabled

Im curious to check if Re-Bar can work on my motherboard using this instruction:
https://github.com/xCuri0/ReBarUEFI/wiki/Enabling-hidden-4G-decoding

Im stuck on 4 step. I find 4G Decod using UEFITOOL, extracted body, next i used [IRFExtractor_0.3.6] to save output file.
Output file doesn't contain "4G Decod".

I attached original bios file and txt output.

Z97XGAMING3.zip
Section_Freeform_subtype_GUID_97E409E6-4CC1-11D9-81F6-000000000000_Setup_Setup_body IFR.txt

Hello, I have an interesting case. I have an Asus M16 2021 laptop and I'm using an eGPU (RX 6800 XT) through an Oculink x4 Gen 4.0 connection. It's connected via the NVMe port and works great, but without resizable BAR (re-bar) support.

I managed to enable resizable BAR support using setup_var.efi, but it only works for the built-in GPU (dGPU, 3060). I even disabled the dGPU and iGPU through the BIOS, but it still doesn't work.

An interesting fact is that in Linux, I can boot with pci=realloc and set bar2 to 16GB. I can even dynamically resize it at runtime using resource2_resize.

So, my thought is the following: Is it possible to create this an EFI tool that can be invoked manually before booting into Windows?

It would be great for people like me who don't have the option to flash the entire BIOS.

Thank you in advance!
Miro.

System

• Motherboard: Asus P8Z77-V Deluxe
• BIOS Version: 2104
• GPU: Nvidia Tesla M40
• CPU: i7-3770K (22nm Ivy Bridge with support for PCIe 3.0)
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied
• DSDT looks similar
• I have read Common issues (and fixes)

Description

I'm trying to get an Nvidia Tesla M40 (24gb) working on an Asus P8Z77-V Deluxe. I've did all the modifications required/advised here but the card still report a code 12 in windows. I succeed to get a ReBar working on a Polaris RX 590 (it was showing 8gb on GPU-Z and properly displayed in Large Memory on Device Manager on Windows (as can be seen on the screenshots). I've tried the registry trick for the AMD drivers but wasn't seeing the option appearing in the Adrenalin software.

When I plug the Tesla M40, only the PCI bus is displayed in Large Memory.

Trying to boot on Linux (Ubuntu 20.04 Server) the kernel is spamming the following error (extract from dmesg):

[    0.077256] kernel: [mem 0xdf200000-0xf7ffffff] available for PCI devices
[...]
[    5.106057] kernel: nvidia: loading out-of-tree module taints kernel.
[    5.106073] kernel: nvidia: module license 'NVIDIA' taints kernel.
[    5.106075] kernel: Disabling lock debugging due to kernel taint
[    5.135499] kernel: nvidia-nvlink: Nvlink Core is being initialized, major device number 234
[    5.135505] kernel: 
[    5.137085] kernel: nvidia 0000:01:00.0: enabling device (0000 -> 0002)
[    5.137846] kernel: NVRM: This PCI I/O region assigned to your NVIDIA device is invalid:
                       NVRM: BAR1 is 0M @ 0x0 (PCI:0000:01:00.0)
[    5.137868] kernel: nvidia: probe of 0000:01:00.0 failed with error -1
[    5.137882] kernel: NVRM: The NVIDIA probe routine failed for 1 device(s).
[    5.137883] kernel: NVRM: None of the NVIDIA devices were initialized.
[    5.138031] kernel: nvidia-nvlink: Unregistered Nvlink Core, major device number 234

I'm not sure what size was set with ReBarState.exe when I saved this specific dmesg log file so the first line telling the memory available for PCI devices might be different. Although the rest (specifically NVRM: BAR1 is 0M @ 0x0 (PCI:0000:01:00.0) ) was always displayed regardless of the size specified.

Troubleshooting tried

• Deactivating as many devices in the bios as possible
• Using two separate source of power (from the same PSU) for the two pins of the GPU (in case it was a power issue).
• Tested the GPU in a different system to check if the GPU had an issue (it works in a different system with the same drivers tested here).
• Tested Windows 10 (22H2) and 11.
• Tested with lower memory assigned with ReBarState.exe (2048).
• looked at the DSDT and it seemed to have the proper values so I didn't change it.
• Tinkering with hidden unlocked options related to PCIe in the Asus bios.

I've noticed that the GPU-Z on windows when the Polaris card was displayed was mentionning 8GB of VRAM on BAR0 and the linux drivers complains about BAR1. I thought that this could maybe be the issue? But I have no idea how to change that.

I'm at my wit end on this issue, I've seen in a different issue that it was stated that what a Tesla M40 requires is not exactly ResizableBar but only large address, but I would have expected it to work with this activated as that's what I had to activate on another motherboard to get it working there.

If you have ideas of what is wrong and can help, that would be nice. Thanks for the great project!

System

• Motherboard: Asus h110m-e/m.2
• BIOS Version: 4210
• CPU: i7-7700
• RAM: 32gb 2400mhz
• GPU: arc a770 16g
• [✓] CSM is turned off
• [✓] 4G decoding is enabled
• [✓] Secure boot is disabled
• [✓] UEFIPatch is applied
• [✓] I have read [Common issues (and fixes)]
  Description
  succefully flashed modded bios with ai suite ez update using the swap trick and ReBarState says success,
  rebooting with no problems but never get the hardware change message and gpu-z shows rebar is disabled.
  running ReBarState again shows current ReBarState 32 (or whichever number i set)
  tried many different bar sizes with no luck.

H110M-E-M2-ASUS-4210.zip
H110M-E-M2-ASUS-4210-patched.zip

[sidpr@strogg build]$ make
[ 50%] Building CXX object CMakeFiles/ReBarState.dir/ReBarState.cpp.o
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:89:9: error: ‘uint32_t’ does not name a type
   89 |         uint32_t attr;
      |         ^~~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:15:1: note: ‘uint32_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
   14 | #include <sys/ioctl.h>
  +++ |+#include <cstdint>
   15 | #endif
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:90:9: error: ‘uint8_t’ does not name a type
   90 |         uint8_t value;
      |         ^~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:90:9: note: ‘uint8_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:97:1: error: ‘uint8_t’ does not name a type
   97 | uint8_t GetState() {
      | ^~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:97:1: note: ‘uint8_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:111:17: error: ‘uint8_t’ was not declared in this scope
  111 | bool WriteState(uint8_t rBarState) {
      |                 ^~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:111:17: note: ‘uint8_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp: In function ‘int main()’:
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:142:9: error: ‘uint8_t’ was not declared in this scope
  142 |         uint8_t reBarState;
      |         ^~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:142:9: note: ‘uint8_t’ is defined in header ‘<cstdint>’; did you forget to ‘#include <cstdint>’?
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:151:9: error: ‘reBarState’ was not declared in this scope
  151 |         reBarState = GetState();
      |         ^~~~~~~~~~
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:151:22: error: ‘GetState’ was not declared in this scope; did you mean ‘setstate’?
  151 |         reBarState = GetState();
      |                      ^~~~~~~~
      |                      setstate
/home/sidpr/ReBarUEFI/ReBarState/ReBarState.cpp:186:23: error: ‘WriteState’ cannot be used as a function
  186 |         if (WriteState(reBarState)) {
      |             ~~~~~~~~~~^~~~~~~~~~~~
make[2]: *** [CMakeFiles/ReBarState.dir/build.make:76: CMakeFiles/ReBarState.dir/ReBarState.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/ReBarState.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

using Gnu Make 4.4.1, GCC 13.1.1, on Arch Linux

Is this for adding support to unsupported motherboards or GPUs too?

I've read through the README and looked through the supported mobos list, which seems to imply that this is just for hacking CPU/mobo support and not GPU support.

Would this work on my system?
5800X / B550 / 2080 Ti

System

• Motherboard: Asus X99-S
• BIOS Version: 4101
• GPU: AMD Radeon 5700 XT
• [] CSM is turned off
• 4G decoding is enabled (had to mod)
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)

Description

So I flashed the modded BIOS according to your instructions and it works all well under Windows. However, I wanted to boot a non-uefi formatted USB drive and had to enable CSM. Now it boots directly into Windows, showing a Windows 7-esque loading screen and completely skipping GRUB, which is my preferred boot option. It's just a blank screen, then a text message saying something like "Booting the operating system" and then the Windows loading screen.

I can't get into the setup either via DEL key or from Windows.

Is there anything I can do besides clearing CMOS (which may not work) or reflashing?

Thanks!

MB: Asus ROG STRIX Z270-I GAMING
CPU: 7700K
GPU: RTX 3080
RAM: 16GB

With the latest BIOS for my motherboard (Version 2001), I added ReBarDxe and unencapsulated using UEFITool.
I flash the modified BIOS with AFUWin64 as described in the linked guide, enable 4G decoding and disable CSM.
BAR at 256MB

BAR at 1024MB - Only iGPU posts, Freeze at BIOS logo, removing GPU boots back into Windows.
BAR at Unlimited - Only iGPU posts, Bluescreen at during boot, Stop code: WDF VIOLATION

I repeated this with UEFIPatch and the linked patches.txt and checked for page-files (there are none), and I get the same results.

I'm currently trying DSDT patching but the only thing under Large Memory is:
[0000002000000000 - 0000002FFFFFFFFF] PCI Express Root Complex
And I am not able to find AmiBoardInfo using UEFITool.

Guidance or incite would be greatly appreciated.

System

• Motherboard: ASUS X99M-WS，
• BIOS Version: 4001
• GPU: RTX A6000 / Titan RTX

Description
Describe the issue here. Do not ask if it will work on a certain device try and see it yourself. Make sure CSM is off and 4G decoding is on

Doubled checked and confirm CSM is off / all UEFI only, and above 4G decoding is enabled.

Followed miyconst's youtube instruction to append the ReBar.fss to the BIOS downloaded from ASUS website, and flashed the modified BIOS back to the mobo using BIOS flashback successfully.

And then run into the following issue (as shown in photo) when running the ReBarState as Administrator .

`Writing value of 10 / 1024 MB to ReBarState

Failed to write ReBarState UEFI variable
GetLastError: 5
You can close the app now.`

Tried different inputs, for example 10, 20, 32 and 0, the returned errors are the same.

I just quickly looked into the code but was not able to figure out what does GetLastError 5 mean.

I tried Extracting the dsdt included in to this DXE driver but failed.

bios

System

• Motherboard: AB350 Gaming Rev:1
• BIOS Version:51h MOD
• GPU: RX 6600 Eagle
• [Y] CSM is turned off
• [Y] 4G decoding is enabled
• [Y ] UEFIPatch is applied (see README for more information)
• RX 6600 Eagle 8g Vram , with the Nitro there was no way for it to work well RX580 Nitro 4096 Vram
• 2 Nvme , one on board port and one with pcie adapter.
  Description

Well, that with above64 and 2g of BAR on a RX580Nitro 4g, it gives me microblocks and an FPS drop of about 80 to 40.
The value of the BAR 512, 1024, 2048 does not matter. 2048 is the limit for graphics with 4g of vram (as I understand).
But if I don't activate above64 in the bios and I put 1024 of BAR, it behaves perfectly. Without the above64 it is the maximum 1024 because it does not matter if they change the MMIO, it does not admit more than 1024 and below.

As seen with SAM ON 2048 the minimum FPS drops to half, it's strange, it seems that SAM and my Hardware don't get along.

This is problem: https://gitlab.freedesktop.org/drm/amd/-/issues/1864

The memory range FFFFFFFFFF

System

• Motherboard: asus x99 deluxe
• BIOS Version: 4101
• GPU: RTX 3080Ti
• I tried this on my motherboard but it doesn't work. Does anyone have a Bios file with modify resizable bar enabled for asus x99 deluxe?
  Thanks MARK-PC

System

• Motherboard: Gigabyte G1.Sniper Z170-CF
• BIOS Version: American Megatrends Inc. F22f, 09-03-2018 (https://www.gigabyte.com/Motherboard/G1Sniper-Z170-rev-10/support#support-dl-bios)
• GPU: MSI Radeon™ RX 6700 XT GAMING X 12G
• CSM is turned off
• 4G decoding is enabled
• UEFIPatch is applied (see Using UEFIPatch for more information). On some motherboards DSDT Patching is also needed
• I have read Common issues (and fixes)

Description

I don't know what I'm looking at in the screenshots. I'm told to search for a GUID but UEFITool doesn't jump me there so I need to dig around and once I find something that looks right, I must eyeball back and forth between the search result and what I have in the main window to make sure it all matches.

There's screenshots that supposedly show the difference between what a good bios patch and bad bios patch look like but it does not clearly indicate where to look, only to look for a pad file, but the bios has a couple of those already. Am I looking for this pad file at the end of the volume I added ReBarDxe.ffs to? I don't know.

I grabbed the latest NE UEFITool to try and see if it was less confusing / if I did it right and what I find is that I have a message in the NE UefiTool window of my patched rom that says

FfsParser::checkProtectedRanges: AMI v2 protected range [290000h:5C6A00h] hash mismatch, opened image may refuse to boot

Is this borked or not? I can assume it is but the guide does not helpfully explain this. It's frustrating. The whole old engine vs new engine situation confuses things further. I didn't know the answer to "What is 'non-NE?' until i looked at the full releases page and not the specifically linked 0.28 version.

EDIT: Alright I do see what it says to check for now I think I just glossed over it. You can check for this issue by comparing pad files of the modified volume in UEFITool.

Maybe this ought to be moved to another paragraph or as part of one of the image captions?

As for the protected range I'm not sure whether to proceed or not still.

Wondering if this is compatible with a dell oem. If not looks like a nice tweak to systems.

System

• Motherboard: Asus Z97 Maximus VII Hero
• BIOS Version: 3503
• GPU: 6700 XT

Alright, so to summarize what happened last time, we've managed to get my motherboard to run with up to 24 GB of ram while 32 GB failed to run.

Let me know if you require anything else that wasn't put on GitHub or Winraid

System

• Motherboard: plexHD x99
• BIOS Version:n/a
• GPU: s7000 (r7 370x)
• [ ✓] CSM is turned off
• [✓ ] 4G decoding is enabled
• [ ✓] UEFIPatch is applied (see README for more information)

Description

Describe the issue here.

Hi everyone. I did everything as described in the faq several times, but rebar did not turn on. I am using a modified driver from nimez but still nothing works.

System

• Motherboard: Asus Sabertooth Z97 MARK S
• BIOS Version: 2702
• GPU: AMD Gigabyte Aorus 5700XT
• CPU: i7 4770k
• [y] CSM is turned off
• [y] 4G decoding is enabled
• [y] UEFIPatch is applied (see README for more information)

Description

Did UEFITool Method. It created a .ROM file After that i used the UEFIPatch with Powershell which corrected one path: 114Ah 75080FBAE80F89442430 - EB080FBAE80F89442430. Then i got Pad file created at PcIHostBridge which i corrected with MMtool.

The i renamed the .rom to .cap but Flash Utility says file is not proper Bios.

The Modded file is in .rom format but i need .cap.

Have seen a youtube video where someone extraced the modded.rom file from UEFITool and then used HxD to switch the Capsual HEX binaries from the original to the modded and then just renamed the rewritten file to the original one.

https://youtu.be/aISCfhK05Rk?t=1375

I did the same but in Flash Utilitily then says it's not a UEFI Bios and doesn't even start to flash.

This Motherboard isn't in the list yet as i see but other z97 types worked.

Im pretty new to this so please don't harass me to much :D

USB-Stick is In FAT32 Format

If I can, may pls tell me how?

Laptop problem
😅

The Failed to write ReBarState UEFI variable error message provides zero information about the problem, but according to the SetFirmwareEnvironmentVariableExA docs, it should be possible to get at least something using the GetLastError method.

Hi there,

I have a ASUS P9X79 PRO motherboard with an i7-4930K and 32GB of ram, gpu is a Sapphire RX 580 Nitro+ 8GB.

The issue is that, after having successfully added your .ffs module to the bios, and also enabled the bios submenu for Above 4G Decoding, and having enabled the 4G Decoding itself, the board POSTs just fine but it doesn't boot anything, it just stucks to a black screen.

If i disable the Above 4G option, i can boot to windows just fine. Also another thing is that adding your module to the bios, breaks the sata contoller somehow (it gives code 10 in device manager, sata controller is a Marvell 91xx, but this is not a problem as i am booting from a NVMe drive).

I didn't do the UEFIPatch part, and the program said that it cannot find anything to patch.

Also i didn't do the DSDT patching step as you indicated in the guide that HEDT boards do not need it.

(But i still tried to look in the extracted DSDT file from the AmiBoardInfo module if i could find any of the lines you pointed to in the guide, and i couldn't find anything that matched)

I tried also updating the GOP in the vga bios to the last version, but to no avail.

UPDATE by xCuri0:
The issue above has been fixed by a new UEFIPatch (make sure to uncomment it) and DSDT patch, however there have been some reports of NVIDIA GPUs still not working on Windows.

UPDATE from @nefh:
dmesg_2GPU_KWin.txt

Since you've renamed the topic, I thought about some summary that could be pasted into first post.
I've recorded also some boot comparison videos for illustration, hope it's easier to get it this way.

All of the following issues happen only with ReBAR>1GB, only when RTX is receiving 64bit address space for BAR1.
In all cases ended in successful boot, the ReBAR works correct.

1. Boot to Windows - bad case
a) If RTX is connected to any display, even as a secondary input, then booting stops after POST, when Windows bootloader starts. The PC responds with instant turn off for power button push.
b) With Radeon connected alone or with no cables attached at all, the boot proceeds without any problems:

2. Boot to Linux - better case
Connecting display to RTX results in visibility problems during booting.
a) When display shows output from Radeon with secondary input connected to RTX, there is black screen instead of bootloaders UI. Any graphics seems to be a problem, even AMI logo is missing in POST screen. The visibility comes back during text mode.
b) When display shows output from RTX, the screen stays entirely black for whole boot sequence.
However, in all cases we have successful boot and proper display in desktop mode.

3. Misc info
The issue is independent to bootloaders. No matter if boot goes through rEFInd, GRUB or straight to Windows, the behavior is the same. Removing Radeon entirely and keeping only RTX also gives no effect - issues stays the same. RTX3090 VBIOS is the newest one.

Thanks for all your support and great work!

• used REBAR Legacy On.reg file, without it there are no option to enable bar in amd control panel.
• mobo: GA-X79-UP4 rev 1.0
• Bios: F6a, Tried F7, F8g
• GPU: 6700XT
• ReBarDxe.ffs is applied
• 4G Decode is on
• CSM is 0ff
• PCIBus is OK see comment #9 (comment)
• Tried Running 16GB of RAM (Dual Channel) instead of 32GB (Quad Channel)

Hi, so i did manage to unlock ReBAR on my Sandy Bridge - E motherboard (GA-X79-UP4), by modding bios with UEFITool, but values greater than 1GB = my motherboard just straight trying recovery from second bios, which it fails, then reboots and tries again to ∞, until i manually do recovery by pressing reset and power buttons at the same time for 10 seconds, then it flashes 2nd bios to M.

I've also tried those secret setup_var's

setup_var 0x12E 0x1
setup_var 0x9 0x1
setup_var 0xF 0x1
setup_var 0x16 0x1
setup_var 0x1C 0x2
setup_var 0x4F 0x2
setup_var 0x6C 0x0
setup_var 0x4 0x1
setup_var 0xC 0x5
setup_var 0xD 0x5
setup_var 0x17 0x1
setup_var 0xF5 0x0
setup_var 0xD8 0x1
setup_var 0x55 0x1

PCIe Sub Decode, VarStoreInfo (VarOffset/VarName): 0x12E
Relaxed Ordering, VarStoreInfo (VarOffset/VarName): 0x9
Extended Synch, VarStoreInfo (VarOffset/VarName): 0xF
AtomicOp Requester Enable, VarStoreInfo (VarOffset/VarName): 0x16
Target Link Speed, VarStoreInfo (VarOffset/VarName): 0x1C
Server Class, VarStoreInfo (VarOffset/VarName): 0x4F
Energy Performance, VarStoreInfo (VarOffset/VarName): 0x6C
Above 4G Decoding, VarStoreInfo (VarOffset/VarName): 0x4
Maximum Payload, VarStoreInfo (VarOffset/VarName): 0xC
Maximum Read Request, VarStoreInfo (VarOffset/VarName): 0xD
AtomicOp Egress Blocking, VarStoreInfo (VarOffset/VarName): 0x17
DRAM RAPL BWLIMIT, VarStoreInfo (VarOffset/VarName): 0xF5
DCA Support, VarStoreInfo (VarOffset/VarName): 0xD8
Local APIC Mode, VarStoreInfo (VarOffset/VarName): 0x55

Motherboards which don't support at least 2GB BAR size are considered not working.

If you're having any issues please see Common issues (and fixes) before replying.

Use this format in your comment:

• Motherboard: (motherboard model)
• GPU: (gpu model, include vram if it comes with multiple vram sizes)
• UEFIPatch: (yes or no depending on if you needed it)
• DSDT Patch: (yes or no depending on if you needed it)
• BAR Size: (BAR size that GPU-Z (Windows) or lspci (Linux) shows)
• RAM: (the amount of ram in your pc)
• Resume from sleep: (works or doesn't. if sleep doesnt work even without rebar then leave blank)
• Notes: any additional information and screenshots of GPU-Z Resizable BAR and GPU control panel showing rebar working optionally with CPU-Z and/or Device Manager Large Memory showing too.