physical memory userspace/kernel split on Linux x86-64

[Karaoui mohamed lamine]

2015-05-27 3:12 GMT+02:00 Le Tan <tamlokveer at gmail.com>:

> Hi,
> Is there an explict split between userspace and kernel in physical
> memory on Linux x86-64? That is, given a physical address, can I tell
> whether this address is from userspace or not?
>

No. The same physical address can be  used by both the kernel and the
userspace.
The kernel and userspace share the same physical memory.
Any memory page can be allocated for the userspace then released (free)
then re-allocated for kernel use.

As far as I know, in virtual address space, the kernel will use the
> upper half and the userspace will use the lower half. But what about
> in physical address space?


> Thanks very much!
>
> Le
>
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