Liming, Thanks for looking into this! Can someone also answer my question about the expected behavior of taking an exception in OVMF? Is the CpuDeadloop() expected? Thanks, Andrew Fish > On Oct 10, 2019, at 6:19 PM, Gao, Liming wrote: > > Andrew: > I verify the change (2de1f611be06ded3a59726a4052a9039be7d459b MdeModulePkg/BdsDxe: Also call PlatformBootManagerWaitCallback on 0) in Emulator. > It works, because PCD value is set to 10 in Emulator. > > Before this change, if TimeOut PCD is zero, BdsEntry doesn’t call PlatformBootManagerWaitCallback(). > After this change, if TimeOut PCD is zero, BdsEntry still call PlatformBootManagerWaitCallback(). So, it trigs this issue. I agree your fix. > > Pete: > Will you contribute the patch to fix this hang issue in OVMF? > > Thanks > Liming > From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of Andrew Fish via Groups.Io > Sent: Friday, October 11, 2019 5:12 AM > To: devel@edk2.groups.io; Pete Batard > Subject: [edk2-devel] OVMF is crashing for me in master > > This is my flavor of OVMF: build -p OvmfPkg/OvmfPkgX64.dsc -a X64 -t XCODE5 > > It looks like I took an exception? Is it expected that an unhandled exception just hang in a dead loop? I would have expected some serial output about the failure? > > Looks like a divide by zero exception. The exception context has PC and FP so I can manually walk the stack. Yikes I see PlatformBootManagerWaitCallback() will fault if PcdPlatformBootTimeOut is zero? > /Volumes/Case/UDK2018(master)>git grep PcdPlatformBootTimeOut -- *.dsc > ArmVirtPkg/ArmVirtQemu.dsc:194: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3 > ArmVirtPkg/ArmVirtQemuKernel.dsc:191: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3 > ArmVirtPkg/ArmVirtXen.dsc:122: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3 > EmulatorPkg/EmulatorPkg.dsc:236: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|L"Timeout"|gEfiGlobalVariableGuid|0x0|10 > OvmfPkg/OvmfPkgIa32.dsc:541: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0 > OvmfPkg/OvmfPkgIa32X64.dsc:553: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0 > OvmfPkg/OvmfPkgX64.dsc:552: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0 > OvmfPkg/OvmfXen.dsc:470: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0 > UefiPayloadPkg/UefiPayloadPkgIa32.dsc:344: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3 > UefiPayloadPkg/UefiPayloadPkgIa32X64.dsc:345: gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3 > > > OK PcdPlatformBootTimeOut is zero on Ovmf, so how did this ever work? > > > Ahhh gotom.... > /Volumes/Case/UDK2018(master)>git blame -L344,344 /Volumes/Case/UDK2018/MdeModulePkg/Universal/BdsDxe/BdsEntry.c > 2de1f611be0 (Pete Batard 2019-09-25 23:50:05 +0800 344) PlatformBootManagerWaitCallback (0); > > > This call causes a divide by zero if PcdPlatformBootTimeOut == 0. > > This fixes my crash: > diff --git a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c > index 70df6b841a..d6ae43e900 100644 > --- a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c > +++ b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c > @@ -1634,6 +1634,11 @@ PlatformBootManagerWaitCallback ( > UINT16 Timeout; > > Timeout = PcdGet16 (PcdPlatformBootTimeOut); > + if (Timeout == 0) { > + Timeout = 100; > + } else { > + Timeout = (Timeout - TimeoutRemain) * 100 / Timeout; > + } > > Black.Raw = 0x00000000; > White.Raw = 0x00FFFFFF; > @@ -1643,7 +1648,7 @@ PlatformBootManagerWaitCallback ( > Black.Pixel, > L"Start boot option", > White.Pixel, > - (Timeout - TimeoutRemain) * 100 / Timeout, > + Timeout, > 0 > ); > } > > > > lldb debugger output: > > (lldb) bt > * thread #1, stop reason = signal SIGTRAP > * frame #0: 0x0000000007b58a70 CpuDxe.dll:CpuDeadLoop() + 13 at /Volumes/Case/UDK2018/MdePkg/Library/BaseLib/CpuDeadLoop.c:31 > frame #1: 0x0000000007b61222 CpuDxe.dll:CommonExceptionHandlerWorker() + 674 at /Volumes/Case/UDK2018/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiDxeSmmCpuException.c:115 > frame #2: 0x0000000007b61624 CpuDxe.dll:CommonExceptionHandler() + 36 at /Volumes/Case/UDK2018/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c:40 > frame #3: 0x0000000007b5ff26 CpuDxe.dll:HasErrorCode() + 230 > (lldb) fr sel 1 > frame #1: 0x0000000007b61222 CpuDxe.dll:CommonExceptionHandlerWorker() + 674 at /Volumes/Case/UDK2018/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiDxeSmmCpuException.c:115 > 91 (ExternalInterruptHandler[ExceptionType]) (ExceptionType, SystemContext); > 92 } else if (ExceptionType < CPU_EXCEPTION_NUM) { > 93 // > 94 // Get Spinlock to display CPU information > 95 // > 96 while (!AcquireSpinLockOrFail (&ExceptionHandlerData->DisplayMessageSpinLock)) { > 97 CpuPause (); > 98 } > 99 // > 100 // Initialize the serial port before dumping. > 101 // > 102 SerialPortInitialize (); > 103 // > 104 // Display ExceptionType, CPU information and Image information > 105 // > 106 DumpImageAndCpuContent (ExceptionType, SystemContext); > 107 // > 108 // Release Spinlock of output message > 109 // > 110 ReleaseSpinLock (&ExceptionHandlerData->DisplayMessageSpinLock); > 111 // > 112 // Enter a dead loop if needn't to execute old IDT handler further > 113 // > 114 if (ReservedVectors[ExceptionType].Attribute != EFI_VECTOR_HANDOFF_HOOK_BEFORE) { > -> 115 CpuDeadLoop (); > 116 } > 117 } > 118 } > 119 > (lldb) p ExceptionType > (EFI_EXCEPTION_TYPE) $0 = 0 > (lldb) p SystemContext.SystemContextX64->Rip > (UINT64) $1 = 0x0000000007a9cc38 > (lldb) p SystemContext.SystemContextX64->Rbp > (UINT64) $2 = 0x0000000007e8fc20 > (lldb) efi_backtrace --pc 0x0000000007a9cc38 --frame 0x0000000007e8fc20 --symbols > frame 0: 0x07a9cc38 BdsDxe:PlatformBootManagerWaitCallback + 35 at /Volumes/Case/UDK2018/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c:1646:37 > frame 1: 0x07a9e744 BdsDxe:BdsWait + 269 at /Volumes/Case/UDK2018/MdeModulePkg/Universal/BdsDxe/BdsEntry.c:344:3 > frame 2: 0x07a9dff9 BdsDxe:BdsEntry + 2620 at /Volumes/Case/UDK2018/MdeModulePkg/Universal/BdsDxe/BdsEntry.c:1002:5 > frame 3: 0x07eb367d DxeCore:DxeMain + 2680 at /Volumes/Case/UDK2018/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c:544:3 > frame 4: 0x07e943cb DxeCore:_ModuleEntryPoint + 20 at /Volumes/Case/UDK2018/MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.c:48:3 > frame 5: 0x07edc947 DxeIpl.dll`AsmEnableCache > frame 6: 0x07ee1e4e DxeIpl:HandOffToDxeCore + 509 at /Volumes/Case/UDK2018/MdeModulePkg/Core/DxeIplPeim/X64/DxeLoadFunc.c:113:3 > frame 7: 0x07ee0604 DxeIpl:DxeLoadCore + 1354 at /Volumes/Case/UDK2018/MdeModulePkg/Core/DxeIplPeim/DxeLoad.c:449:3 > frame 8: 0x07eeff2f PeiCore.dll`PeiCore.cold.3 + 847 > frame 9: 0x07ee9d04 PeiCore:PeiCore + 163 at /Volumes/Case/UDK2018/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c:502:3 > frame 10: 0x0082c387 0x0082c387 > frame 11: 0x00825dd7 0x00825dd7 > frame 12: 0x0082ad27 0x0082ad27 > frame 13: 0x0082b3a8 0x0082b3a8 > frame 14: 0x0082bf23 0x0082bf23 > frame 15: 0x00825e24 0x00825e24 > frame 16: 0x00823af2 0x00823af2 > frame 17: 0xfffd1db8 SecMain:SecStartupPhase2 + 67 at /Volumes/Case/UDK2018/OvmfPkg/Sec/SecMain.c:858:3 > frame 18: 0xfffd1d67 SecMain:SecCoreStartupWithStack + 420 at /Volumes/Case/UDK2018/OvmfPkg/Sec/SecMain.c:821:3 > frame 19: 0xfffd1e14 SecMain:ProcessLibraryConstructorList + 0 at /Volumes/Case/UDK2018/Build/OvmfX64/DEBUG_XCODE5/X64/OvmfPkg/Sec/SecMain/DEBUG/AutoGen.c:201 > > (lldb) l /Volumes/Case/UDK2018/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c:1646 > 1646 (Timeout - TimeoutRemain) * 100 / Timeout, > 1647 0 > 1648 ); > 1649 } > 1650 > 1651 /** > 1652 The function is called when no boot option could be launched, > 1653 including platform recovery options and options pointing to applications > 1654 built into firmware volumes. > 1655 > (lldb) l /Volumes/Case/UDK2018/MdeModulePkg/Universal/BdsDxe/BdsEntry.c:344 > 344 PlatformBootManagerWaitCallback (0); > 345 DEBUG ((EFI_D_INFO, "[Bds]Exit the waiting!\n")); > 346 } > 347 > 348 /** > 349 Attempt to boot each boot option in the BootOptions array. > 350 > 351 @param BootOptions Input boot option array. > 352 @param BootOptionCount Input boot option count. > 353 @param BootManagerMenu Input boot manager menu. > 354 > > > Thanks, > > Andrew Fish > >