On Sat, 31 Aug 2002 10:39:20 -0700 (PDT) Mcen navaraj <mcensamuel@yahoo.com> wrote: >hi, > >what is the use of gates in the intel processors ? >what is the use of interrupt gate ? If you refer to Intel x86 arch you have to distinguish between three types of interrupt gates which are inserted through three different functions in the Global Descriptor Table: - interrupt gates (which can NOT be accessed from User Mode processes. They are used for activate interrupt handlers); - system gates (can be accessed from User Mode processes. The four exceptions 3,4,5 and 128 are activated by means of system gates. In particular 128 is the well-known int 0x80 which is associated to the exception handler system_call you refer to; - trap gates (can NOT be accessed from User Mode processes and all exception handlers except the four described before are activated through these ones). >please tell me how many segments are created when a >process is created ?.What are the segments are created >when we create a process ? AFAIK Linux creates at boot time some segments. -two for kernel : kernel data segment and kernel code segment; -two for userland : user data segment and user code segment (this last ones are shared by all processes in User Mode); -in Linux 2.2 a task state segment (TSS) for each process, in Linux 2.4 simply one TSS per CPU; -a default Local Descriptor Table segment usually shared by all processes (but very rarely used). Regards, Angelo Dell'Aera 'buffer' <buffer@users.sourceforge.net> -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
