Lenovo M920s - resizable BAR mod?

[digits]

Greetings,

I've completed the mod that would allow the stock BIOS to support resizable BAR for the Intel ARC A380 that I have installed. (see: https://github.com/xCuri0/ReBarUEFI)

I am currently stuck on not being able to flash the modified BIOS. The stock Lenovo tools will not allow it, which I kind of figured would be the case. Does anyone know if there is some way around it? I've researched and found that maybe Intel FPT is what I'd be looking to use, but I am not 100% certain that's the case and really don't want to brick the machine.

Thanks,
Digits

System Specs:
Intel i5-8600/32GB Crucial DDR4/512GB TeamGroup NVME/2TB TeamGroup SSD/Sparkle Intel ARC A380 - running Fedora 39.

[Brot]

I am currently stuck on not being able to flash the modified BIOS. The stock Lenovo tools will not allow it, which I kind of figured would be the case. Does anyone know if there is some way around it? I've researched and found that maybe Intel FPT is what I'd be looking to use, but I am not 100% certain that's the case and really don't want to brick the machine. 

This Thread is Google Hit #1 for "m920s resizable bar", so i thought i'll add my failed attempt here. Maybe it'll help others, maybe someone might find another way.


- used the USB Drive Package, UEFI M1UKT77A/1.0.0.119  25 Apr 2024
- successfully Inserted the ReBarDxe Module to the PciBus Module
- used UEFIPatch with the ReBarUEFI projects patches.txt -> none were applicable
- tried to enable hidden 4G decoding -> no hidden option
- the UEFI does not provide such Option, but i flashed it anyways 
-- to answer digits' question: format a flash drive to fat32, put all content of m1ujt77usa.zip onto it's root, replace the imageM1U.ROM with the modified, boot from it. After 2 promts it will start flashing. 
- Result: ResBar is not working

- It meets the following criteria in DTST patching section:
| Systems without 4G decoding even in hidden settings, this fix will only work in Linux for them though (atleast with GPUs)
- Tried to find the GUID for DSDT modification, no matches

Gave up at this point. Good luck to the next guy, i'd be happy to find your mail in my inbox

[myansweris42]

• You have to search for  "Above 4G" and you will come up with:
  

1. 1) "Memory Remap" and Edit:Guide says not to mess with Memory Remap as it is not the same. 
   
2. 2)"Above 4GB MMIO Bios assignment"
   

• You then follow the modGrubShell instuctions to enablethe second of these. After  the second of these , GPU-Z shows 4G encoding enabled. Edit:GPU-Z can't really tell if 4G encoding is enabled.
  

I am currently stuck on not being able to flash the modified BIOS. The stock Lenovo tools will not allow it, which I kind of figured would be the case. Does anyone know if there is some way around it? I've researched and found that maybe Intel FPT is what I'd be looking to use, but I am not 100% certain that's the case and really don't want to brick the machine. 

This Thread is Google Hit #1 for "m920s resizable bar", so i thought i'll add my failed attempt here. Maybe it'll help others, maybe someone might find another way.
- used the USB Drive Package, UEFI M1UKT77A/1.0.0.119  25 Apr 2024
- successfully Inserted the ReBarDxe Module to the PciBus Module
- used UEFIPatch with the ReBarUEFI projects patches.txt -> none were applicable
- tried to enable hidden 4G decoding -> no hidden option
- the UEFI does not provide such Option, but i flashed it anyways 
-- to answer digits' question: format a flash drive to fat32, put all content of m1ujt77usa.zip onto it's root, replace the imageM1U.ROM with the modified, boot from it. After 2 promts it will start flashing. 
- Result: ResBar is not working
- It meets the following criteria in DTST patching section:
| Systems without 4G decoding even in hidden settings, this fix will only work in Linux for them though (atleast with GPUs)
- Tried to find the GUID for DSDT modification, no matches
Gave up at this point. Good luck to the next guy, i'd be happy to find your mail in my inbox

[whateverkid]

So rather than mod the bios, I just did a bit of kernel hackery and made a patch which fixes this in the Linux kernel.  Apply the patch to your kernel, compile & install it with a kernel command line parameter of `pci=realloc=on` ... This enables Intel ARC resizable BAR without UEFI hackery on the C621 / Lenovo P920:

https://github.com/ben-efros/grimtickle-...bars.patch

Code:

b2:00.0 VGA compatible controller: Intel Corporation DG2 [Arc A380] (rev 05) (prog-if 00 [VGA controller])
        Subsystem: ASRock Incorporation Device 6004
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 32 bytes
        Interrupt: pin ? routed to IRQ 410
        NUMA node: 1
        IOMMU group: 21
        Region 0: Memory at e5000000 (64-bit, non-prefetchable) [size=16M]
        Region 2: Memory at 28000000000 (64-bit, prefetchable) [size=8G] <<<<<<< YAY!!!!!!!!!!!!!!!!!!!!!!
        Expansion ROM at e6000000 [disabled] [size=2M]
        Capabilities: [40] Vendor Specific Information: Len=0c <?>
        Capabilities: [70] Express (v2) Endpoint, IntMsgNum 0
                DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
                        ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset+ SlotPowerLimit 0W TEE-IO-
                DevCtl: CorrErr+ NonFatalErr+ FatalErr+ UnsupReq-
                        RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+ FLReset-
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq+ AuxPwr- TransPend-
                LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
                        ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
                LnkCtl: ASPM Disabled; RCB 64 bytes, LnkDisable- CommClk-
                        ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                LnkSta: Speed 2.5GT/s, Width x1
                        TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
                DevCap2: Completion Timeout: Range B, TimeoutDis+ NROPrPrP- LTR+
                        10BitTagComp+ 10BitTagReq+ OBFF Not Supported, ExtFmt+ EETLPPrefix-
                        EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
                        FRS- TPHComp- ExtTPHComp-
                        AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-
                        AtomicOpsCtl: ReqEn-
                        IDOReq- IDOCompl- LTR- EmergencyPowerReductionReq-
                        10BitTagReq- OBFF Disabled, EETLPPrefixBlk-
                LnkCap2: Supported Link Speeds: 2.5GT/s, Crosslink- Retimer- 2Retimers- DRS-
                LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
                        Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
                        Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
                LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
                        EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
                        Retimer- 2Retimers- CrosslinkRes: unsupported
        Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable+ 64bit+
                Address: 00000000fee00078  Data: 0000
                Masking: 00000000  Pending: 00000000
        Capabilities: [d0] Power Management version 3
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
                Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [100 v1] Alternative Routing-ID Interpretation (ARI)
                ARICap: MFVC- ACS-, Next Function: 0
                ARICtl: MFVC- ACS-, Function Group: 0
        Capabilities: [420 v1] Physical Resizable BAR
                BAR 2: current size: 8GB, supported: 256MB 512MB 1GB 2GB 4GB 8GB
        Capabilities: [400 v1] Latency Tolerance Reporting
                Max snoop latency: 0ns
                Max no snoop latency: 0ns
        Kernel driver in use: i915
        Kernel modules: i915, xe