X86-64: Difference between revisions
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===How do I detect if the CPU is 64 bits ?=== |
===How do I detect if the CPU is 64 bits ?=== |
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You can find that out by checking CPUID. All AMD64 compliant processors have the longmode-capable-bit turned on in the extended feature flags (bit 29) in EDX, after calling CPUID with EAX=0x80000001. There are also other bits required by long mode, but you can see those yourself in CPUID at [http:// |
You can find that out by checking CPUID. All AMD64 compliant processors have the longmode-capable-bit turned on in the extended feature flags (bit 29) in EDX, after calling CPUID with EAX=0x80000001. There are also other bits required by long mode, but you can see those yourself in CPUID at [http://support.amd.com/us/Processor_TechDocs/24594.pdf AMD general purpose instruction reference] |
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==How do I enable Long Mode ?== |
==How do I enable Long Mode ?== |
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