physical memory userspace/kernel split on Linux x86-64

[Le Tan]

Hi Min-Hua,

2015-05-27 22:23 GMT+08:00 Min-Hua Chen <orca.chen at gmail.com>:
> Hi,
>
> Linux kernel basically manages all available physical memory pages.
> If user-space need a page, kernel allocates a page for it. Hence a
> physical page may be in mapped to user-space virtual address or
> kernel-space virtual address or both.
>
> The user-space and kernel-space exist in virtual address space, not
> physical.

Very clear description! I always seems to be confused by some basic concept. :)

Thanks!

Le

> Thanks,
> Min-Hua
>
> On Wed, May 27, 2015 at 09:12:11AM +0800, Le Tan wrote:
>> 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?
>> 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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