Mail Archives: djgpp/1997/01/06/08:11:06
"Mark Habersack" <grendel AT ananke DOT amu DOT edu DOT pl> wrote:
>2. Memory protection. On 286 memory has been protected by means of
>segment sizes and location stored in descriptors in either LDT or
>GDT. i386 enables another protection scheme: each page, information
>on which is stored in Page Directories and Directory Tables, can have
>its own set of protection bits - this allows for a very minute memory
>protection. i486 extends the scheme even more by making possible
>creation of read-only pages for all users of the OS (including the OS
>itself - unlike on i386 where OS, i.e. software running at the Ring
>0, can read/write any area of memory).
HOW DO YOU DO THAT?? Sorry for the screaming. It's just that I am
working on a multitasking operating system, and are now doing the
memory protection/virtual memory stuff, and found it quite anoing that
I was unable to protect the kernal from itself. I only got
documentation on the i386, so I was not aware that it was possible, to
write-protect memory for supervisor code on a i486. Is there any good
documentation on the i486 around? Somting like the 386INTEL.TXT from
Intel.
Kurt. Programmer Funcom/R&D
The above expressions is not ment to represent Funcom.
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