Hi All, Pls help me here by answering following two queries. If my understanding is incorrect in asking the question pls correct me: 1. In case of Paging and discontiguous memory allocation for a particular process, is it possible that all the segments say DS, SS, CS, Heap and all can be in different page frames. I am asking this for a particular segment (I know all the segments can be in different non contiguous pages seperately, but what about one segment in different non contiguous page frames). For example lets say stack segment (or data segment) which is in RAM requires 45 pages and in RAM 45 pages are not contiguous avilable, so can it be reside from page frame no 100-125 and then again in 140-160 ? 2. In case of execution of fast interrupt handler when other interrupts are disable, if device controller generate interrupt then it will not reaches to CPU ? Is it loss of interrupts and not a good condition on system/driver ? Can we ignore it safely for our driver or we must not fall into this scenario ? 3. Inside kernel page fault should not happen, I was trying to understand it w.r.t copy from/to usr api. Say on usr address the particular page is not there and kernel wants to copy it in kernel address space? What will happen if we use memcpy rather than copy from usr, will the kernel crash due to page fault? how copy from usr prevents this? Is the page fault handler code always remains in RAM in case of Linux Kernel ? 4. In case of read/write system call, a normal user program wants to acess some file or more specifically (direct or indirect block of particular inode). This user space process page table which is in RAM doesn't contain valid bit for particular pages which correspond to these blocks. If these blocks are not in page-cache, it will be bring ito RAM by vector i/o with the help of bio-vec data structures. Will this scenario triggers the page fault inside kernel ? Best Regards, Krishna