Thanks everyone. I think i got enough information for further study. Thanks, Vijay On Thu, Jun 21, 2012 at 7:10 PM, kishore sheik ahamed <linuxinme@xxxxxxxxx> wrote: > Hey Vijay > > I am a newbie too. Just sharing what I could go through. > > It is said that Kernel or atleast a part of kernel needs to be non paged for > fast interrupt access etc as pinned memory > Wiki says > > Pinned/Locked/Fixed pages > > Operating systems have memory areas that are pinned (never swapped to > secondary storage). For example, interrupt mechanisms rely on an array of > pointers to their handlers, such as I/O completion and page fault. If the > pages containing these pointers or the code that they invoke were pageable, > interrupt-handling would become far more complex and time-consuming, > particularly in the case of page fault interrupts. Hence, some part of the > page table structures is not pageable. > > Some pages may be pinned for short periods of time, others may be pinned for > long periods of time, and still others may need to be permanently pinned. > For example: > > The paging supervisor code and drivers for secondary storage devices on > which pages reside must be permanently pinned, as otherwise paging wouldn't > even work because the necessary code wouldn't be available. > Timing-dependent components may be pinned to avoid variable paging delays. > Data buffers that are accessed directly by peripheral devices that use > direct memory access or I/O channels must reside in pinned pages while the > I/O operation is in progress because such devices and the buses to which > they are attached expect to find data buffers located at physical memory > addresses; regardless of whether the bus has a memory management unit for > I/O, transfers cannot be stopped if a page fault occurs and then restarted > when the page fault has been processed. > > There are other two discussion thread which say kernel is non-pageable and > now due to growing kernel Data structures it is allowed > > http://kerneltrap.org/node/6404 > > http://kerneltrap.org/node/8206 > > > Regards > > Kishore > > > > On Thu, Jun 21, 2012 at 5:57 PM, Vijay Chauhan <kernel.vijay@xxxxxxxxx> > wrote: >> >> Hello, >> >> I am newbie. >> It has been said "kernel memory is not pageable" >> What does it mean? There is no concept of kernel virtual address? >> >> Any simple explanation will help me to udnerstand. >> >> Thanks, >> Vijay >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
