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Attempting to debug why a PCIe card doesn't enumerate

Purchased a 2nd hand Mellanox CX455A ConnectX-4 EDR + 100GbE x16 PCIe card. In theory the card was in working order, but on fitting to 3 different PCs the card never enumerated on the PCIe bus.

Attempted to investigate on a HP Pavilion 590-p0053na running AlmaLinux 9.5

The output of dmidecode -t slot for the x16 slot used didn't change between the slot being unpopulated and fitting the CX455A:

Handle 0x003E, DMI type 9, 17 bytes
System Slot Information
	Designation: J10
	Type: PCI Express x16
	Data Bus Width: 8x or x8
	Current Usage: Available
	Length: Short
	ID: 48
	Characteristics:
		3.3 V is provided
		PME signal is supported
	Bus Address: 0000:00:1f.7

Whereas when fit a working ConnectX-3 the dmidecode Current Usage changes from Available to In Use, as well as the reported Bus Address changing:

Handle 0x003E, DMI type 9, 17 bytes
System Slot Information
	Designation: J10
	Type: PCI Express x16
	Data Bus Width: 8x or x8
	Current Usage: In Use
	Length: Short
	ID: 48
	Characteristics:
		3.3 V is provided
		PME signal is supported
	Bus Address: 0000:00:01.1

The output of sudo lspci -nn -vvv changes between the slot being unpopulated and fitting the CX455A but the addition of the following root port:

00:01.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 PCIe GPP Bridge [6:0] [1022:15d3] (prog-if 00 [Normal decode])
	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: 64 bytes
	Interrupt: pin ? routed to IRQ 26
	IOMMU group: 1
	Bus: primary=00, secondary=10, subordinate=10, sec-latency=0
	I/O behind bridge: 0000f000-00000fff [disabled]
	Memory behind bridge: fff00000-000fffff [disabled]
	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled]
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR+ NoISA- VGA- VGA16+ MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [50] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D3 NoSoftRst- PME-Enable+ DSel=0 DScale=0 PME-
	Capabilities: [58] Express (v2) Root Port (Slot+), MSI 00
		DevCap:	MaxPayload 512 bytes, PhantFunc 0
			ExtTag+ RBE+
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 512 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L1 <64us
			ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk-
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 2.5GT/s (downgraded), Width x4 (downgraded)
			TrErr- Train- SlotClk+ DLActive- BWMgmt+ ABWMgmt-
		SltCap:	AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug- Surprise-
			Slot #0, PowerLimit 0.000W; Interlock- NoCompl+
		SltCtl:	Enable: AttnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq- LinkChg-
			Control: AttnInd Unknown, PwrInd Unknown, Power- Interlock-
		SltSta:	Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet- Interlock-
			Changed: MRL- PresDet- LinkState+
		RootCap: CRSVisible+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt+ EETLPPrefix+, MaxEETLPPrefixes 1
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd+
			 AtomicOpsCap: Routing- 32bit+ 64bit+ 128bitCAS-
		DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis- LTR- OBFF Disabled, ARIFwd-
			 AtomicOpsCtl: ReqEn- EgressBlck-
		LnkCap2: Supported Link Speeds: 2.5-8GT/s, Crosslink- Retimer- 2Retimers- DRS-
		LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance De-emphasis: -6dB
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
		Address: 00000000fee00000  Data: 0000
	Capabilities: [c0] Subsystem: Hewlett-Packard Company Device [103c:8433]
	Capabilities: [c8] HyperTransport: MSI Mapping Enable+ Fixed+
	Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
	Capabilities: [150 v2] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
		RootCmd: CERptEn+ NFERptEn+ FERptEn+
		RootSta: CERcvd- MultCERcvd- UERcvd- MultUERcvd-
			 FirstFatal- NonFatalMsg- FatalMsg- IntMsg 0
		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
	Capabilities: [270 v1] Secondary PCI Express
		LnkCtl3: LnkEquIntrruptEn- PerformEqu-
		LaneErrStat: LaneErr at lane: 0 7
	Capabilities: [2a0 v1] Access Control Services
		ACSCap:	SrcValid+ TransBlk+ ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans+
		ACSCtl:	SrcValid+ TransBlk- ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans-
	Capabilities: [370 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			  PortCommonModeRestoreTime=0us PortTPowerOnTime=10us
		L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
			   T_CommonMode=0us LTR1.2_Threshold=0ns
		L1SubCtl2: T_PwrOn=10us
	Kernel driver in use: pcieport

When fit a working ConnextX-3 x8 PCIe card the output for the same root port is:

00:01.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 PCIe GPP Bridge [6:0] [1022:15d3] (prog-if 00 [Normal decode])
	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: 64 bytes
	Interrupt: pin ? routed to IRQ 26
	IOMMU group: 1
	Bus: primary=00, secondary=10, subordinate=10, sec-latency=0
	I/O behind bridge: 0000f000-00000fff [disabled]
	Memory behind bridge: fff00000-000fffff [disabled]
	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled]
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR+ NoISA- VGA- VGA16+ MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [50] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D3 NoSoftRst- PME-Enable+ DSel=0 DScale=0 PME-
	Capabilities: [58] Express (v2) Root Port (Slot+), MSI 00
		DevCap:	MaxPayload 512 bytes, PhantFunc 0
			ExtTag+ RBE+
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 512 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L1 <64us
			ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk-
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 2.5GT/s (downgraded), Width x4 (downgraded)
			TrErr- Train- SlotClk+ DLActive- BWMgmt+ ABWMgmt-
		SltCap:	AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug- Surprise-
			Slot #0, PowerLimit 0.000W; Interlock- NoCompl+
		SltCtl:	Enable: AttnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq- LinkChg-
			Control: AttnInd Unknown, PwrInd Unknown, Power- Interlock-
		SltSta:	Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet- Interlock-
			Changed: MRL- PresDet- LinkState+
		RootCap: CRSVisible+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt+ EETLPPrefix+, MaxEETLPPrefixes 1
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd+
			 AtomicOpsCap: Routing- 32bit+ 64bit+ 128bitCAS-
		DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis- LTR- OBFF Disabled, ARIFwd-
			 AtomicOpsCtl: ReqEn- EgressBlck-
		LnkCap2: Supported Link Speeds: 2.5-8GT/s, Crosslink- Retimer- 2Retimers- DRS-
		LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance De-emphasis: -6dB
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
		Address: 00000000fee00000  Data: 0000
	Capabilities: [c0] Subsystem: Hewlett-Packard Company Device [103c:8433]
	Capabilities: [c8] HyperTransport: MSI Mapping Enable+ Fixed+
	Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
	Capabilities: [150 v2] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
		RootCmd: CERptEn+ NFERptEn+ FERptEn+
		RootSta: CERcvd- MultCERcvd- UERcvd- MultUERcvd-
			 FirstFatal- NonFatalMsg- FatalMsg- IntMsg 0
		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
	Capabilities: [270 v1] Secondary PCI Express
		LnkCtl3: LnkEquIntrruptEn- PerformEqu-
		LaneErrStat: LaneErr at lane: 0 7
	Capabilities: [2a0 v1] Access Control Services
		ACSCap:	SrcValid+ TransBlk+ ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans+
		ACSCtl:	SrcValid+ TransBlk- ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans-
	Capabilities: [370 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			  PortCommonModeRestoreTime=0us PortTPowerOnTime=10us
		L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
			   T_CommonMode=0us LTR1.2_Threshold=0ns
		L1SubCtl2: T_PwrOn=10us
	Kernel driver in use: pcieport

The changes to the lspci output for the root port, from the non-working ConnectX-4 to working ConnectX-3 fitted are:

@@ -27,14 +27,14 @@
 	IOMMU group: 1
 	Bus: primary=00, secondary=10, subordinate=10, sec-latency=0
 	I/O behind bridge: 0000f000-00000fff [disabled]
-	Memory behind bridge: fff00000-000fffff [disabled]
-	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled]
+	Memory behind bridge: fcc00000-fcdfffff [size=2M]
+	Prefetchable memory behind bridge: 00000000f0800000-00000000f0ffffff [size=8M]
 	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
 	BridgeCtl: Parity- SERR+ NoISA- VGA- VGA16+ MAbort- >Reset- FastB2B-
 		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
 	Capabilities: [50] Power Management version 3
 		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
-		Status: D3 NoSoftRst- PME-Enable+ DSel=0 DScale=0 PME-
+		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
 	Capabilities: [58] Express (v2) Root Port (Slot+), MSI 00
 		DevCap:	MaxPayload 512 bytes, PhantFunc 0
 			ExtTag+ RBE+
@@ -44,15 +44,15 @@
 		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
 		LnkCap:	Port #0, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L1 <64us
 			ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
-		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk-
+		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk+
 			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
-		LnkSta:	Speed 2.5GT/s (downgraded), Width x4 (downgraded)
-			TrErr- Train- SlotClk+ DLActive- BWMgmt+ ABWMgmt-
+		LnkSta:	Speed 8GT/s (ok), Width x8 (ok)
+			TrErr- Train- SlotClk+ DLActive+ BWMgmt+ ABWMgmt-
 		SltCap:	AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug- Surprise-
 			Slot #0, PowerLimit 0.000W; Interlock- NoCompl+
 		SltCtl:	Enable: AttnBtn- PwrFlt- MRL- PresDet- CmdCplt- HPIrq- LinkChg-
 			Control: AttnInd Unknown, PwrInd Unknown, Power- Interlock-
-		SltSta:	Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet- Interlock-
+		SltSta:	Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet+ Interlock-
 			Changed: MRL- PresDet- LinkState+
 		RootCap: CRSVisible+
 		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
@@ -62,14 +62,14 @@
 			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
 			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd+
 			 AtomicOpsCap: Routing- 32bit+ 64bit+ 128bitCAS-
-		DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis- LTR- OBFF Disabled, ARIFwd-
+		DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis- LTR- OBFF Disabled, ARIFwd+
 			 AtomicOpsCtl: ReqEn- EgressBlck-
 		LnkCap2: Supported Link Speeds: 2.5-8GT/s, Crosslink- Retimer- 2Retimers- DRS-
-		LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
+		LnkCtl2: Target Link Speed: 8GT/s, EnterCompliance- SpeedDis-
 			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
 			 Compliance De-emphasis: -6dB
-		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
-			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
+		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+ EqualizationPhase1+
+			 EqualizationPhase2+ EqualizationPhase3+ LinkEqualizationRequest-
 			 Retimer- 2Retimers- CrosslinkRes: unsupported
 	Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
 		Address: 00000000fee00000  Data: 0000
@@ -91,7 +91,7 @@
 		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
 	Capabilities: [270 v1] Secondary PCI Express
 		LnkCtl3: LnkEquIntrruptEn- PerformEqu-
-		LaneErrStat: LaneErr at lane: 0 7
+		LaneErrStat: LaneErr at lane: 1 2 3 6
 	Capabilities: [2a0 v1] Access Control Services
 		ACSCap:	SrcValid+ TransBlk+ ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans+
 		ACSCtl:	SrcValid+ TransBlk- ReqRedir+ CmpltRedir+ UpstreamFwd+ EgressCtrl- DirectTrans-

The following differences are the expected side effect of the card failing to enumerate:

Setting Non working Working
Memory behind bridge None 2M
Prefetchable memory behind bridge None 8M
Link Status Speed 2.5GT/s Width x4 DLActive- Working Speed 8GT/s Width x8 DLActive+
Device Control 2 ARIFwd- Working ARIFwd+
Link Control 2 Target Link Speed: 2.5GT/s Target Link Speed: 8GT/s
Link Status 2 EqualizationComplete- EqualizationPhase1- EqualizationPhase2- EqualizationPhase3- EqualizationComplete+ EqualizationPhase1+ EqualizationPhase2+ EqualizationPhase3+

Both the non working and working card have same lanes Lane Error Status, so don't see that as significant.

The Slot Status PresDet bit is clear with the non-working card and set with the working card. From the PCIe specification:

This bit indicates the presence of an adapter in the slot, reflected by the logical “OR” of the Physical Layer in-band presence detect mechanism and, if present, any out-of-band presence detect mechanism defined for the slot’s corresponding form factor. Note that the in-band presence detect mechanism requires that power be applied to an adapter for its presence to be detected. Consequently, form factors that require a power controller for hot-plug must implement a physical pin presence detect mechanism.

Defined encodings are:
0b Slot Empty
1b Card Present in slot

So, with the non-working card looks like the root port attempts to enumerate the card but fails for some reason.

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