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fix logic error for CPUs lacking xAPIC (thanks to Brian for reporting this)

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This was SVN commit r7628.
This commit is contained in:
janwas 2010-06-19 18:22:47 +00:00
parent 85bfdf0983
commit eb5f0ce639
1 changed files with 16 additions and 8 deletions
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24
source/lib/sysdep/arch/x86_x64/topology.cpp
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@ -137,6 +137,21 @@ static size_t LogicalPerCache()
// core, package and shared cache. if they are available, we can determine
// the exact topology; otherwise we have to guess.
// side effect: `removes' (via std::unique) duplicate IDs.
static bool AreApicIdsUnique(u8* apicIds, size_t numProcessors)
{
u8* const end = std::unique(apicIds, apicIds+numProcessors);
const size_t numIds = end-apicIds;
if(numIds == numProcessors) // all unique
return true;
// the only legitimate cause of duplication is when no xAPIC is
// present (i.e. all are 0)
debug_assert(numIds == 1);
debug_assert(apicIds[0] == 0);
return false;
}
/**
* @return an array of the processors' unique APIC IDs or zero if
* no xAPIC is present or process affinity is limited.
@ -161,17 +176,10 @@ static const u8* ApicIds()
};
if(os_cpu_CallByEachCPU(StoreApicId::Callback, (uintptr_t)&apicIds) == INFO::OK)
{
const size_t numProcessors = os_cpu_NumProcessors();
u8* end = std::unique(apicIdStorage, apicIdStorage+numProcessors);
if(end == apicIdStorage+1) // exactly one unique value
debug_assert(apicIdStorage[0]); // all 0 (no APIC supported)
else
{
debug_assert(end == apicIdStorage+numProcessors); // all unique
if(AreApicIdsUnique(apicIdStorage, os_cpu_NumProcessors()))
apicIds = apicIdStorage; // return valid array from now on
}
}
}
return apicIds;
}