I think the OS can just use the segment mechanism to implement the virtual memory management. When I look through the intel manual find that the Segment Descriptor have a member P, when the P is set this segment is located in the physical memory otherwise the segment is not located,but If this flag is clear, the processor generates a segment-not-present exception when a segment selector that points to the segment descriptor is loaded into a segment register. Just like the page mechanism we can just use the segment mechanism to manage the virtual memory. But it is Inefficiencies for swapping all segment from disk to memory and this way is no use in the Multiprocessor.
regards
Fan
2012/11/1 Fan Yang <lljyangfan@xxxxxxxxx>
2012/11/1 Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>Hi..
multitasking and memory management are not directly related IMHO, but
On Wed, Oct 31, 2012 at 9:30 PM, Fan Yang <lljyangfan@xxxxxxxxx> wrote:
> Hi all:
> I have a problem, if i don't active the page mechanism just use the
> segment mechanism at the x86 cpu, how can I manage the Multi-tasking?
you're right that we need process address space switching.
I think what you're going to do is already done by Linux kernel port
to non MMU architectures. Can't recall which ones, so try to check
https://en.wikipedia.org/wiki/Memory_management_unit for further
examples
-
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.comHi Mulyadi SantosaVery honored to see your reply.Yes, the page mechanism can protect different task to interfere each other by mapping different task to different physical memory, and this work is already done by kernel.In order to solve the prev problem I look through the intel manualhttp://download.intel.com/design/processor/manuals/253668.pdf ,and in chapter 3.1 I see this sentence "Segmentation provides a mechanism of isolating individual code, data, and stack modules so that multiple programs (or tasks) can run on the same processor without interfering with one another." then this manual tell me that "There is no mode bit to disable segmentation. The use of paging, however, is optional." that is to say the segment mechanism must be support in the OS, but the page mechanism is optional, but at the manual I can't find any example to explain how to use the single segment mechanism to protect the different tasks to interfere with one another ,so I have a guess you just see.BTW, I try the 2.6.32.27 kernel version but nothing changed.ThanksFan
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
