__PHYSICAL_MEMORY_EXTENSION__

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samiam95124
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__PHYSICAL_MEMORY_EXTENSION__

Post by samiam95124 »

Hi,

Can someone tell me what:

__PHYSICAL_MEMORY_EXTENSION__

Does in the APIC example code? Is that the same as PAE? And why would the APIC care about that?

Thanks,

Scott Franco
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BrightLight
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Re: __PHYSICAL_MEMORY_EXTENSION__

Post by BrightLight »

In the provided example code, the system is assumed to be in 32-bit mode with a 32-bit address bus. That code checks if the system is using PAE paging, thus a 36-bit address bus. If so, it supports relocating the local APIC to addresses to higher memory locations than 4 GB, the maximum address on a system with a 32-bit address bus.
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Beginner Mistakes wrote:This may look like a set of tutorials to copy & paste, plus a forum to ask your questions whenever you get stuck. This is not so.
You know your OS is advanced when you stop using the Intel programming guide as a reference.
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