[lldb-dev] Building LLDB when LLVM is built with threading disabled

[Zachary Turner]

It sounds to me like you simply need to link in libpthread.   "LLVM with
threading enabled" is a very confusing thing.  Compiling LLVM with
"threading disabled" DOES NOT mean that you promise your application will
be single-threaded.  It only means that you agree that a very specific
subset of operations will not be thread-safe.  If someone is deciding
whether to link libpthread based on the value of LLVM_ENABLE_THREADING,
that right there is a bug, because the two are independent.  LLDB always
needs to link libpthread.

That said, it might be interesting just to know why this broke recently.
 In that case, you can use the "git bisect" command to track down the
offending changelist.

On Wed, Sep 10, 2014 at 10:09 AM, Keno Fischer <kfischer at college.harvard.edu
> wrote:

> This is copied from a user who sent me his error message, but I saw
> the same (the errors can be fixed by linking in -lpthread manually, so
> it's probably just a make system issue):
>
> llvm[6]: Linking Release+Asserts Shared Library liblldb.so
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbExpression.a(ClangExpressionParser.o):
> In function
> `lldb_private::ClangExpressionParser::Parse(lldb_private::Stream&)':
>
> ClangExpressionParser.cpp:(.text._ZN12lldb_private21ClangExpressionParser5ParseERNS_6StreamE+0x397):
> warning: the use of `mktemp' is dangerous, better use `mkstemp' or
> `mkdtemp'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function
> `lldb_private::NativeProcessLinux::OperationArgs::OperationArgs(lldb_private::NativeProcessLinux*)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux13OperationArgsC2EPS0_+0x1a):
> undefined reference to `sem_init'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function
> `lldb_private::NativeProcessLinux::OperationArgs::~OperationArgs()':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux13OperationArgsD2Ev+0x9):
> undefined reference to `sem_destroy'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function
> `lldb_private::NativeProcessLinux::ServeOperation(lldb_private::NativeProcessLinux::OperationArgs*)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14ServeOperationEPNS0_13OperationArgsE+0xd):
> undefined reference to `sem_post'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14ServeOperationEPNS0_13OperationArgsE+0x24):
> undefined reference to `sem_wait'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14ServeOperationEPNS0_13OperationArgsE+0x6c):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function `lldb_private::NativeProcessLinux::DoOperation(void*)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux11DoOperationEPv+0x36):
> undefined reference to `sem_post'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux11DoOperationEPv+0x4e):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function `lldb_private::NativeProcessLinux::StopMonitor()':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux11StopMonitorEv+0x19):
> undefined reference to `sem_destroy'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux11StopMonitorEv+0x26):
> undefined reference to `sem_destroy'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function
> `lldb_private::NativeProcessLinux::LaunchInferior(lldb_private::Module*,
> char const**, char const**, char const*, char const*, char const*,
> char const*, lldb_private::ProcessLaunchInfo const&,
> lldb_private::Error&)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14LaunchInferiorEPNS_6ModuleEPPKcS5_S4_S4_S4_S4_RKNS_17ProcessLaunchInfoERNS_5ErrorE+0xd1):
> undefined reference to `sem_init'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14LaunchInferiorEPNS_6ModuleEPPKcS5_S4_S4_S4_S4_RKNS_17ProcessLaunchInfoERNS_5ErrorE+0xe1):
> undefined reference to `sem_init'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14LaunchInferiorEPNS_6ModuleEPPKcS5_S4_S4_S4_S4_RKNS_17ProcessLaunchInfoERNS_5ErrorE+0x116):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function `lldb_private::NativeProcessLinux::AttachToInferior(unsigned
> long, lldb_private::Error&)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux16AttachToInferiorEmRNS_5ErrorE+0x1bb):
> undefined reference to `sem_init'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux16AttachToInferiorEmRNS_5ErrorE+0x1cc):
> undefined reference to `sem_init'
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux16AttachToInferiorEmRNS_5ErrorE+0x222):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function `lldb_private::NativeProcessLinux::LaunchOpThread(void*)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14LaunchOpThreadEPv+0x25):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(NativeProcessLinux.o):
> In function `lldb_private::NativeProcessLinux::AttachOpThread(void*)':
>
> NativeProcessLinux.cpp:(.text._ZN12lldb_private18NativeProcessLinux14AttachOpThreadEPv+0x25):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function
> `ProcessMonitor::OperationArgs::OperationArgs(ProcessMonitor*)':
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor13OperationArgsC2EPS_+0x1a):
> undefined reference to `sem_init'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::OperationArgs::~OperationArgs()':
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor13OperationArgsD2Ev+0x9):
> undefined reference to `sem_destroy'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function
> `ProcessMonitor::ServeOperation(ProcessMonitor::OperationArgs*)':
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor14ServeOperationEPNS_13OperationArgsE+0xd):
> undefined reference to `sem_post'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor14ServeOperationEPNS_13OperationArgsE+0x24):
> undefined reference to `sem_wait'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor14ServeOperationEPNS_13OperationArgsE+0x69):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::DoOperation(Operation*)':
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor11DoOperationEP9Operation+0x2a):
> undefined reference to `sem_post'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor11DoOperationEP9Operation+0x3e):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::StopMonitor()':
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor11StopMonitorEv+0x16):
> undefined reference to `sem_destroy'
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor11StopMonitorEv+0x20):
> undefined reference to `sem_destroy'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::ProcessMonitor(ProcessPOSIX*,
> lldb_private::Module*, char const**, char const**, char const*, char
> const*, char const*, char const*, lldb_private::ProcessLaunchInfo
> const&, lldb_private::Error&)':
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXPN12lldb_private6ModuleEPPKcS7_S6_S6_S6_S6_RKNS2_17ProcessLaunchInfoERNS2_5ErrorE+0xd3):
> undefined reference to `sem_init'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXPN12lldb_private6ModuleEPPKcS7_S6_S6_S6_S6_RKNS2_17ProcessLaunchInfoERNS2_5ErrorE+0xe0):
> undefined reference to `sem_init'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXPN12lldb_private6ModuleEPPKcS7_S6_S6_S6_S6_RKNS2_17ProcessLaunchInfoERNS2_5ErrorE+0x116):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::ProcessMonitor(ProcessPOSIX*, unsigned
> long, lldb_private::Error&)':
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXmRN12lldb_private5ErrorE+0x50):
> undefined reference to `sem_init'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXmRN12lldb_private5ErrorE+0x5d):
> undefined reference to `sem_init'
>
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitorC2EP12ProcessPOSIXmRN12lldb_private5ErrorE+0xae):
> undefined reference to `sem_wait'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::LaunchOpThread(void*)':
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor14LaunchOpThreadEPv+0x25):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbPluginProcessLinux.a(ProcessMonitor.o):
> In function `ProcessMonitor::AttachOpThread(void*)':
> ProcessMonitor.cpp:(.text._ZN14ProcessMonitor14AttachOpThreadEPv+0x25):
> undefined reference to `sem_post'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `MonitorChildProcessThreadFunction(void*)':
> Host.cpp:(.text._ZL33MonitorChildProcessThreadFunctionPv+0xf3):
> undefined reference to `pthread_testcancel'
> Host.cpp:(.text._ZL33MonitorChildProcessThreadFunctionPv+0x10b):
> undefined reference to `pthread_testcancel'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadCreate(char const*, void*
> (*)(void*), void*, lldb_private::Error*)':
>
> Host.cpp:(.text._ZN12lldb_private4Host12ThreadCreateEPKcPFPvS3_ES3_PNS_5ErrorE+0x63):
> undefined reference to `pthread_create'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadCancel(unsigned long,
> lldb_private::Error*)':
> Host.cpp:(.text._ZN12lldb_private4Host12ThreadCancelEmPNS_5ErrorE+0xa):
> undefined reference to `pthread_cancel'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadDetach(unsigned long,
> lldb_private::Error*)':
> Host.cpp:(.text._ZN12lldb_private4Host12ThreadDetachEmPNS_5ErrorE+0xa):
> undefined reference to `pthread_detach'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadJoin(unsigned long, void**,
> lldb_private::Error*)':
> Host.cpp:(.text._ZN12lldb_private4Host10ThreadJoinEmPPvPNS_5ErrorE+0xa):
> undefined reference to `pthread_join'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadLocalStorageCreate(void
> (*)(void*))':
>
> Host.cpp:(.text._ZN12lldb_private4Host24ThreadLocalStorageCreateEPFvPvE+0xd):
> undefined reference to `pthread_key_create'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadLocalStorageGet(unsigned int)':
> Host.cpp:(.text._ZN12lldb_private4Host21ThreadLocalStorageGetEj+0x1):
> undefined reference to `pthread_getspecific'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Host.o):
> In function `lldb_private::Host::ThreadLocalStorageSet(unsigned int,
> void*)':
> Host.cpp:(.text._ZN12lldb_private4Host21ThreadLocalStorageSetEjPv+0x1):
> undefined reference to `pthread_setspecific'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Mutex.o):
> In function `lldb_private::Mutex::Mutex(lldb_private::Mutex::Type)':
> Mutex.cpp:(.text._ZN12lldb_private5MutexC2ENS0_4TypeE+0x4c): undefined
> reference to `pthread_mutexattr_init'
> Mutex.cpp:(.text._ZN12lldb_private5MutexC2ENS0_4TypeE+0x7a): undefined
> reference to `pthread_mutexattr_destroy'
> Mutex.cpp:(.text._ZN12lldb_private5MutexC2ENS0_4TypeE+0xa9): undefined
> reference to `pthread_mutexattr_settype'
> Mutex.cpp:(.text._ZN12lldb_private5MutexC2ENS0_4TypeE+0xd6): undefined
> reference to `pthread_mutexattr_settype'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(Mutex.o):
> In function `lldb_private::Mutex::TryLock(char const*)':
> Mutex.cpp:(.text._ZN12lldb_private5Mutex7TryLockEPKc+0x1): undefined
> reference to `pthread_mutex_trylock'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::ProcessRunLock()':
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLockC2Ev+0x7):
> undefined reference to `pthread_rwlock_init'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::~ProcessRunLock()':
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLockD2Ev+0x1):
> undefined reference to `pthread_rwlock_destroy'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::ReadTryLock()':
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock11ReadTryLockEv+0x5):
> undefined reference to `pthread_rwlock_rdlock'
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock11ReadTryLockEv+0x24):
> undefined reference to `pthread_rwlock_unlock'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::ReadUnlock()':
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock10ReadUnlockEv+0x5):
> undefined reference to `pthread_rwlock_unlock'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::SetRunning()':
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock10SetRunningEv+0x5):
> undefined reference to `pthread_rwlock_wrlock'
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock10SetRunningEv+0x11):
> undefined reference to `pthread_rwlock_unlock'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::TrySetRunning()':
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock13TrySetRunningEv+0xa):
> undefined reference to `pthread_rwlock_trywrlock'
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock13TrySetRunningEv+0x20):
> undefined reference to `pthread_rwlock_unlock'
>
> /mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldbHostCommon.a(ProcessRunLock.o):
> In function `lldb_private::ProcessRunLock::SetStopped()':
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock10SetStoppedEv+0x5):
> undefined reference to `pthread_rwlock_wrlock'
>
> ProcessRunLock.cpp:(.text._ZN12lldb_private14ProcessRunLock10SetStoppedEv+0x11):
> undefined reference to `pthread_rwlock_unlock'
> collect2: error: ld returned 1 exit status
> make[6]: ***
> [/mnt/hdd/mlubin/julia-0.4/deps/llvm-svn/build_Release+Asserts/Release+Asserts/lib/liblldb.so]
> Error 1
>
> On Wed, Sep 10, 2014 at 1:00 PM, Zachary Turner <zturner at google.com>
> wrote:
> > Threading should be enabled by default in LLVM, you have to go out of
> your
> > way to disable it.
> >
> >
> > On Tue, Sep 9, 2014 at 5:12 PM, Greg Clayton <gclayton at apple.com> wrote:
> >>
> >> Because LLVM enables threading manually, this is the main reason we
> didn't
> >> use their locking primitives.
> >>
> >> I am not sure if we recently started using any of LLVM threading stuff
> >> that gets disabled (Zach's changes?) when threading isn't enabled in
> LLVM,
> >> but I don't believe we have enabled threading in LLVM builds.
> >>
> >> Can you elaborate on what is making the build fail now after you disable
> >> threads?
> >>
> >> > On Sep 9, 2014, at 4:50 PM, Keno Fischer <
> kfischer at college.harvard.edu>
> >> > wrote:
> >> >
> >> > We build LLVM with threads disabled by default (using make&configure).
> >> > Recently this started causing the LLDB build to fail. I'm not sure if
> >> > this is because of changes to LLDB or the LLVM build system in general
> >> > but it brings me to two questions. First, is it now necessary to build
> >> > LLVM with threads enabled to build LLDB? And, second, if not, is it
> >> > reasonable to link in pthread even when --disable-threads is passed to
> >> > ./configure, since I don't believe LLDB can be built without threading
> >> > support entirely?
> >> >
> >> > Thanks,
> >> > Keno
> >> > _______________________________________________
> >> > lldb-dev mailing list
> >> > lldb-dev at cs.uiuc.edu
> >> > http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> >>
> >> _______________________________________________
> >> lldb-dev mailing list
> >> lldb-dev at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> >
> >
>
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