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  • what is the mode used when page tables of a process are loaded and modified?--KERNEL /USER?
  • are page tables of the process also stored in process control block??
asked in Operating System by Veteran (11.1k points)   | 48 views

@akriti, when page tables are first loaded than that hsould be in kernal mode as Dispacther is responsible for loading a p/c with its content and Dispatcher is called by Kernal mode to execute as far as i know. when talking about modification in page table than a p/c while executing itself can modify it's table. so there should not be Kernal mode in this. Not sure about point 2 though.

2nd ques.. that page table are stored in PCB. nope whole page table is not stored in PCb.there is Memory management information in PCB : includes the information of page table, memory limits, Segment table depending on memory used by the operating system.

for 2nd ques. of yours , source is wikipidia. https://en.wikipedia.org/wiki/Process_control_block

@mohit,i read in galvin that we need priviledged instruction to modify the page tables..

and thanks for he link
and also,can you give some good link regarding which operations are done in kernel mode and user mode..

system calls are perfomed in kernel mode right??

yes @akriti, you are right about 2nd part. and priviledged  inst. are done in kernal mode. it is clearly given in the answer in this link.  I guess, we can trust stackoverflow :) http://stackoverflow.com/questions/35592339/can-you-modify-your-own-page-tables-os-related

alright..and any good link for various operations in user mode and kernel mode?

and also while switchinf from user mode to kernel mode,which system call or instruction is used and vice-versa

@akriti, first try to find it by yourself, it is a good habit and moreover i mostly rely on wikipedia n stackoverflow.so i guess this is the link you need i guess http://stackoverflow.com/questions/1311402/differences-between-user-and-kernel-modes . hope it helps.  no offence though.

thanks @mohit:-)

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