Hello, I use x86 device with FPGA device. The FPGA device acts strangely with Linux, while with vother OS on same HW there is no issue. The Other PCIe device acts find without any issues. Doing lspci after reset, sometimes the device appear and other times not enumerated at all. After reset it is almost always missing. Then I force rescan several times, until it appears in lspci: 03:00.0 RAM memory: Xilinx Corporation Default PCIe endpoint ID (rev ff) After it appears there is still inconsistency when reading configuration BAR with lspci -vv: 03:00.0 RAM memory: Xilinx Corporation Default PCIe endpoint ID Subsystem: Xilinx Corporation Default PCIe endpoint ID 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- Interrupt: pin A routed to IRQ 255 Region 0: [virtual] Memory at 91500000 (32-bit, non-prefetchable) [size=1M] Capabilities: [40] 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: [48] MSI: Enable- Count=1/1 Maskable- 64bit+ Address: 0000000000000000 Data: 0000 Capabilities: [58] Express (v1) Endpoint, MSI 00 DevCap: MaxPayload 256 bytes, PhantFunc 1, Latency L0s <64ns, L1 <1us ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 10.000W DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported- RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+ MaxPayload 128 bytes, MaxReadReq 512 bytes DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend- LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s unlimited ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk- ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- Capabilities: [100 v1] Device Serial Number 00-00-00-00-00-00-00-00 [root@localhost ~]# lspci -xx -s 03:00.00 03:00.0 RAM memory: Xilinx Corporation Default PCIe endpoint ID 00: ee 10 07 00 00 00 10 00 00 00 00 05 00 00 00 00 10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 20: 00 00 00 00 00 00 00 00 00 00 00 00 ee 10 07 00 30: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00 Other tries of reading (without reseting in between): ========= 03:00.0 RAM memory: Xilinx Corporation Default PCIe endpoint ID (rev ff) (prog-if ff) !!! Unknown header type 7f root@localhost ~]# lspci -xx -s 03:00.00 03:00.0 RAM memory: Xilinx Corporation Default PCIe endpoint ID (rev ff) 00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [root@localhost pcimem]# ./pcimem /sys/bus/pci/devices/0000\:03\:00.0/resource0 0 w*100 /sys/bus/pci/devices/0000:03:00.0/resource0 opened. Target offset is 0x0, page size is 4096 mmap(0, 4096, 0x3, 0x1, 3, 0x0) PCI Memory mapped to address 0x7faf91256000. 0x0000: 0xFFFFFFFF ... The BIOS is also different between Linux and the other OS on same HW. Any idea what configuration can cause this behavior ? Thank you, Ran