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Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM

Le 07/08/2018 à 14:53, basti a écrit :
Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
but free -m only show 2GB.

Whats wrong here?
As I know 686 can address 4GB RAM

No. It can address 4 GiB memory space. Memory space does not contain only RAM, it is also used to address system devices such as the graphics controller. The part of the memory address space which is reserved for system devices is often called "PCI hole". Some motherboards reserve a very large amount of address space for the PCI hole, up to 2 GiB as I have already seen. When you are lucky, the RAM which cannot be mapped in the PCI hole can be remapped beyond the 4 GiB boundary. Sometimes it requires to enable an option in the BIOS settings. But you need a 686-pae or amd64 kernel to use RAM beyond 4 GiB, as Michael pointed out.

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