Re: > 1GB physical on x86: Summary so far

Felix Schroeter (
Sun, 13 Jul 1997 22:02:52 +0200 (CEST)


In article <> you write:
>Felix Schroeter <> writes:
>> Does that mean, if you have a 1GB real mem machine, there's 1GB of virtual
>> memory already used for a permanent mapping of the real 1GB of memory?

>But it's really not a big deal since it's only "virtual memory"
>which only costs a few page-table entries (and no swap).

It costs 1GB/1024 = 1MB for the PTEs. And it causes that no user processes
can ever have more than 3GB of VM (in fact a bit less, because the kernel
needs its own VM in addition to the physmem mapping). On systems without
such a permanent mapping, you had a bit less than 4 GB for the VM.

Regards, Felix.