Modify kext / graphics driver to avoid kernel panic

[Applicator]

Hey there 👋
I'm having some trouble lately with my wife's iMac 4k '17 with AMD Radeon Pro 555 GPU.
It's panicking whenever it's set to sleep for more than a few minutes, and I know the kernel panics are caused by the GPU.
It crashes during the boot process regularly, but after 10-15 tries you'll eventually get into macOS Big Sur.
As soon as you reach the OS, everything is fine. You can play games at any setting for hours and I used amphetamine to keep it awake for 5 days now.

So what I would like to do now, is to mod the kexts related to the GPU, to report "everything's fine" to the system during the boot process to make it boot reliably. That's all we need until new iMacs arrive.
But I have no idea what kext, how and where 🥺

I'm not into software that much, so I just hope my idea is not to crazy and impossible. Every hint and help is highly appreciated!

Spoiler: kernel panic

panic(cpu 3 caller 0xffffff7f9972b3a1): "virtual bool IOAccelLegacyDisplayMachine::display_mode_did_change(uint32_t): vendor driver returns false"@/AppleInternal/BuildRoot/Library/Caches/com.apple.xbs/Sources/ IOAcceleratorFamily_kexts/IOAcceleratorFamily-438.7.4/Kext2/ IOAccelLegacyDisplayMachine.cpp:267
Backtrace (CPU 3), Frame : Return Address
0xffffff9219a13620 : 0xffffff801651963d
0xffffff9219a13670 : 0xffffff8016653ae5
0xffffff9219a136b0 : 0xffffff801664566e
0xffffff9219a13700 : 0xffffff80164bfa40
0xffffff9219a13720 : 0xffffff8016518d07
0xffffff9219a13820 : 0xffffff80165190f7
0xffffff9219a13870 : 0xffffff8016cc01cc
0xffffff9219a138e0 : 0xffffff7f9972b3a1
0xffffff9219a138f0 : 0xffffff7f996d7dee
0xffffff9219a13920 : 0xffffff7f9971e595
0xffffff9219a13960 : 0xffffff7f9790fd58
0xffffff9219a13aa0 : 0xffffff7f978fae65
0xffffff9219a13b30 : 0xffffff7f97905b4f
0xffffff9219a13b50 : 0xffffff7f9790a857
0xffffff9219a13bd0 : 0xffffff7f99fe9025
0xffffff9219a13c10 : 0xffffff7f979009ac
0xffffff9219a13ca0 : 0xffffff8016bff47b
0xffffff9219a13d00 : 0xffffff8016c5a349
0xffffff9219a13d60 : 0xffffff80166020af
0xffffff9219a13db0 : 0xffffff801651f3a8
0xffffff9219a13e10 : 0xffffff80164f5d35
0xffffff9219a13e70 : 0xffffff801650cb02
0xffffff9219a13f00 : 0xffffff801662b065
0xffffff9219a13fa0 : 0xffffff80164c0226
Kernel Extensions in backtrace: com.apple.iokit.IOGraphicsFamily(576.1)
[88D3A235-5CA8-39D6-977F-3BE4ABFDAEC8]@0xffffff7f978f1000- >0xffffff7f97941fff
dependency: com.apple.iokit.IOPCIFamily(2.9) [017B6656-0279-38F7-917D-97CB6A21AC33]@0xffffff7f96f31000
com.apple.iokit.IOAcceleratorFamily2(438.7.4)[7505C559-03C6-3BE9- A7C2-00CCE2353C38]@0xffffff7f996d7000->0xffffff7f9979bfff
dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5) [7AD4106C-84B4-385D-8DBF-045ACB65D4AC]@0xffffff7f9759d000
dependency: com.apple.iokit.IOPCIFamily(2.9) [017B6656-0279-38F7-917D-97CB6A21AC33]@0xffffff7f96f31000
dependency: com.apple.iokit.IOSurface(269.11) [46840050-0F0B-38AA-9E2A-DE6D3853C354]@0xffffff7f996a5000
dependency: com.apple.iokit.IOGraphicsFamily(576.1) [88D3A235-5CA8-39D6-977F-3BE4ABFDAEC8]@0xffffff7f978f1000
dependency: com.apple.iokit.IOReportFamily(47)[59CB26A7-FF64-3102- A964-24CA0986D77F]@0xffffff7f972cc000
com.apple.kext.AMDFramebuffer(3.1)[3E2DE4FF-99F9-3A29-8EAA- BDD22B462A8A]@0xffffff7f99fe8000->0xffffff7f9a011fff
dependency: com.apple.iokit.IOACPIFamily(1.4) [651110C7-82F0-3264-88EC-E16ED04032B8]@0xffffff7f97646000
dependency: com.apple.iokit.IOPCIFamily(2.9) [017B6656-0279-38F7-917D-97CB6A21AC33]@0xffffff7f96f31000
dependency: com.apple.kext.AMDSupport(3.1.0)[66A5A5CA- E452-3A16-9893-BDEE43D4D335]@0xffffff7f97c7c000
dependency: com.apple.iokit.IOGraphicsFamily(576.1) [88D3A235-5CA8-39D6-977F-3BE4ABFDAEC8]@0xffffff7f978f1000
BSD process name corresponding to current thread: WindowServer Boot args: -no_compat_check
Mac OS version: 19H524
Kernel version:
Darwin Kernel Version 19.6.0: Tue Jan 12 22:13:05 PST 2021; root:xnu-6153.141.16~1/RELEASE_X86_64
Kernel UUID: 64F23D6D-4C30-3FC4-B7C2-9EE0BBA0D29A Kernel slide: 0x0000000016200000
Kernel text base: 0xffffff8016400000
__HIB text base: 0xffffff8016300000
System model name: iMac18,2 (Mac-77F17D7DA9285301) System shutdown begun: NO
Panic diags file available: YES (0x0)
System uptime in nanoseconds: 5294334428 last loaded kext at 4946052314: >AudioAUUC 32768)
loaded kexts:
>AudioAUUC 1.70
@filesystems.autofs 3.0
>AGPM 111.4.4
>!APlatformEnabler 2.7.0d0 >X86PlatformShim 1.0.0 >!AUpstreamUserClient 3.6.8 >!AHDAHardwareConfigDriver 283.15 @kext.AMDRadeonServiceManager 3.1.0 @kext.AMDFramebuffer 3.1.0
>!AHDA 283.15 @kext.AMDRadeonX40003.1.0 >!AGraphicsDevicePolicy 5.2.7 @AGDCPluginDisplayMetrics 5.2.7 >!AHV 1
|IOUserEthernet 1.0.1 |IO!BSerialManager 7.0.6f8 >AGDCBacklightControl 5.2.7 >pmtelemetry 1 @Dont_Steal_Mac_OS_X 7.0.0 >!ABacklight 180.3
1.70 (addr 0xffffff7f9a487000, size
>!A!IPCHPMC 2.0.1 >!AMCCSControl 1.14 >!A!IKBLGraphics 14.0.7 >!ASMCLMU 212 >!AFIVRDriver 4.1.0 >ACPI_SMC_PlatformPlugin >eficheck 1
1.0.0
>!AGFXHDA 100.1.429 >!A!IKBLGraphicsFramebuffer 14.0.7 >!A!ISlowAdaptiveClocking 4.0.0 |Broadcom!B20703USBTransport >!AThunderboltIP 3.1.4 @kext.AMD9500!C 3.1.0 |IO!BUSBDFU 7.0.6f8 @filesystems.apfs 1412.141.1 >!AFileSystemDriver 3.0.1
>!AVirtIO 1.0
@filesystems.hfs.kext 522.100.5 @!AFSCompression.!AFSCompressionTypeDataless1.0.0d1 @BootCache 40 @!AFSCompression.!AFSCompressionTypeZlib
>!ASDXC 1.7.7
|!ABCM5701Ethernet10.3.5
>AirPort.BrcmNIC 1400.1.1
@private.KextAudit 1.0
>!AAHCIPort 341.140.1
>!AACPIButtons 6.1
>!ARTC 2.0
>!ASMBIOS 2.1
>!AACPIEC 6.1
>!AAPIC 1.7
$!AImage4 1
@nke.applicationfirewall 303
$TMSafetyNet 8
@!ASystemPolicy 2.0.0
|EndpointSecurity 1
@kext.triggers 1.0
>!AHIDKeyboard 209
>DspFuncLib 283.15
@kext.OSvKernDSPLib 529 @kext.AMDRadeonX4200HWLibs 1.0 @kext.AMDRadeonX4000HWServices
>!AGraphicsControl 5.2.7
|IOAVB!F 850.1
@!AGPUWrangler 5.2.7
>!ABacklightExpert 1.1.0
>!ASMBus!C 1.0.18d1
>!AHDA!C 283.15
|IOHDA!F 283.15
>IOPlatformPluginLegacy 1.0.0
7.0.6f8
3.1.0
1.0.0
>X86PlatformPlugin 1.0.0 >IOPlatformPlugin!F 6.0.0d8 |IOAccelerator!F2 438.7.4 |IOSlowAdaptiveClocking!F 1.0.0 |Broadcom!BHost!CUSBTransport |IO!BHost!CUSBTransport 7.0.6f8 |IO!BHost!CTransport 7.0.6f8 |IO!B!F 7.0.6f8 |IO!BPacketLogger 7.0.6f8 >!AThunderboltEDMSink 4.2.3 >!AThunderboltDPOutAdapter 6.2.6 >!ASMBusPCI 1.0.14d1 |IONDRVSupport 576.1 @kext.AMDSupport 3.1.0 @!AGraphicsDeviceControl 5.2.7 |IOGraphics!F 576.1 @plugin.IOgPTPPlugin 840.3 >!UHIDMouse 192
>!AHIDMouse 192 |IOUSBHIDDriver 900.4.2 >usb.!UHub 1.2 >usb.IOUSBHostHIDDevice 1.2 >!UAudio 323.4
>usb.cdc 5.0.0
>usb.networking 5.0.0 >usb.!UHostCompositeDevice 1.2 >!AXsanScheme 3
|IOAudio!F 300.2
@vecLib.kext 1.2.0
|IOSerial!F 11
|IOSurface 269.11 @filesystems.hfs.encodings.kext >!AThunderboltDPInAdapter 6.2.6 >!AThunderboltDPAdapter!F 6.2.6 >!AThunderboltPCIDownAdapter >!AHPM 3.4.4
>!A!ILpssI2C!C 3.0.60 >!A!ILpssDmac 3.0.60
>!A!ILpssI2C 3.0.60 >!AThunderboltNHI 5.8.6
7.0.6f8
|IOThunderbolt!F
|IOAHCIBlock!S |IOEthernetAVB!C
|IO80211!F 1200.12.2b1 >mDNSOffloadUserClient 1.0.1b8 >corecapture 1.0.4 |IOSkywalk!F 1 >usb.!UHostPacketFilter 1.0 |IOUSB!F 900.4.2
|IOAHCI!F 290.0.1
7.6.1 316.100.5 1.1.0
1 2.5.4
>!A!ILpssGspi 3.0.60 >usb.!UXHCIPCI 1.2 >usb.!UXHCI 1.2 >!AEFINVRAM 2.1 >!AEFIRuntime 2.1 |IOSMBus!F 1.1 |IOHID!F 2.0.0 $quarantine 4 $sandbox 300.0 @Kext.!AMatch 1.0.0d1 >DiskImages 493.0.0 >!AFDEKeyStore 28.30 >!AEffaceable!S 1.0 >!ASSE 1.0 >!AKeyStore 2
>!UTDM 489.120.1 |IOSCSIBlockCommandsDevice >!ACredentialManager 1.0 >KernelRelayHost 1 >!ASEPManager 1.0.1 >IOSlaveProcessor 1 |IOUSBMass!SDriver 157.140.1 |IOSCSIArchitectureModel!F |IO!S!F 2.1
|IOUSBHost!F 1.2 >!UHostMergeProperties 1.2 >usb.!UCommon 1.0 >!ABusPower!C1.0 |CoreAnalytics!F 1 >!AMobileFileIntegrity @kext.CoreTrust 1 |IOTimeSync!F 840.3 |IONetworking!F 3.4 |IOReport!F 47 >!AACPIPlatform 6.1 >!ASMC 3.1.9
>watchdog 1 |IOPCI!F 2.9 |IOACPI!F 1.4 @kec.pthread 1 @kec.corecrypto 1.0 @kec.Libm 1

 

[IceStormNG]

This is not possible.
a) Big Sur uses a sealed system disk. You cannot touch it or it will not boot anymore.
b) If something went wrong with the hardware, the driver should not report "everything fine". The crash might protect your hardware from getting fried.


How does the machine behaves when it goes to sleep and wakes up? Does it also crash then? Or only during boot?
It could be that the display connection got loose or that your GPU is damaged.

 

[Applicator]

Thank you, even though I was hoping for a different answer.
I know the GPU and probably the entire logic board is done, so I did't care about further damage.
In the mean time, I found a repair shop that will have a look at it and in worst case, will replace the logic board.
I can't leave my wife home with an unreliable system when I'm out of town.
And even if it doesn't matter anymore, it's crashing during sleep and I already checked all the connections.

 

[appltech]

There is a chance tools like this one will work for you: https://github.com/0xbb/gpu-switch
What it does is disabling the AMD graphics on boot, after shutdown, sleep, and hibernation.
More information here: https://apple.stackexchange.com/a/270948