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fix incorrect screening of APIC IDs (now handle OS X's lack of thread affinity and/or running under a VM without complaint)

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This was SVN commit r7797.
This commit is contained in:
janwas 2010-07-24 18:48:25 +00:00
parent 523a6a5819
commit fea6745ec9
1 changed files with 12 additions and 6 deletions
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18
source/lib/sysdep/arch/x86_x64/topology.cpp
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@ -120,18 +120,24 @@ static size_t MaxLogicalPerCache()
// 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.
// if false is returned, the APIC IDs are fishy and shouldn't be used.
// side effect: sorts IDs and `removes' (via std::unique) duplicates.
static bool AreApicIdsUnique(u8* apicIds, size_t numIds)
{
std::sort(apicIds, apicIds+numIds);
u8* const end = std::unique(apicIds, apicIds+numIds);
const size_t numUnique = end-apicIds;
if(numUnique == numIds) // all unique
// all unique => IDs are valid.
if(numUnique == numIds)
return true;
// the only legitimate cause of duplication is when no xAPIC is
// present (i.e. all are 0)
debug_assert(numUnique == 1);
debug_assert(apicIds[0] == 0);
// all zero => the system lacks an xAPIC.
if(numUnique == 1 && apicIds[0] == 0)
return false;
// duplicated IDs => something went wrong. for example, VMs might not
// expose all physical processors, and OS X still doesn't support
// thread affinity masks.
return false;
}