Just to add more, CPL is used to protect the kernel memory from user land programs. e.g. kernel space memory is marked as accessible when CPL=0 thus while running in user mode (CPL=3) you cannot access kernel memory (address space). There are other CPL i.e. 1, 2, which are less privileged then 0 but Linux uses only 0 and 3.
Thanks! On Tue, Jan 6, 2009 at 8:29 AM, Mulyadi Santosa <[email protected]>wrote: > Hi > > On Tue, Jan 6, 2009 at 2:26 PM, battipatisainagendra Bhavaniprasad > <[email protected]> wrote: > > Hi Mr.Mulyadi Santosh, > > Thank you your your reply.I could not understand > > point No.2.Can you give me some tutorial on what is CPL...e.t.c. > > > > Please reply. > > pls check Intel CPU documentation. For a brief explanation, CPL stands > for Current Privilege Level. It denotes the privilege the processor is > currently operating on. CPL=3 means user mode, while CPL=0 means > kernel mode. > > regards, > > Mulyadi. > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to [email protected] > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- http://linuxexplained.blogspot.com
