Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap

From: Simon Jeons
Date: Wed Apr 10 2013 - 22:40:41 EST


Hi H.Peter,
On 04/04/2013 09:13 AM, H. Peter Anvin wrote:
On 04/03/2013 06:11 PM, Simon Jeons wrote:
Why we consider boot_cpu_data.x86_phys_bits instead of e820 map here?

Because x86_phys_bits is what controls how much address space the
processor has. e820 tells us how much *RAM* the machine has, or
specifically, how much RAM the machine had on boot.

I have 8GB memory in my machine, but when I accumulated every e820 ranges which dump in dmesg, there are 25MB memory less then 8GB(1024*8) memory, why 25MB miss?


-hpa


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