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Description
Flashcards by sohib algotimel, updated more than 1 year ago
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Created by sohib algotimel
over 9 years ago
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| Question | Answer |
| what the system calls required t create a child process | Fork is the only way to create a new process in MINIX 3. It creates an exact duplicate of the original process wait for the child to finish, the parent executes a waitpid system call, which just waits until the child terminates , this child process must execute the user command. It does this by using the execve system call, which causes its entire core image to be replaced by the file named in its first parameter. |
| Draw process tree of Minix 3 | |
| how Process are represented in minix 3 | process. A process is basically a program in execution. Associated with each process is its address space, a list of memory locations from some minimum (usually 0) to some maximum, which the process can read and write. In many operating systems, all the information about each process, other than the contents of its own address space, is stored in an operating system table called the process table, which is an array (or linked list) of structures, one for each process currently in existence. |
| how minix 3 is made fault tolerant | The reincarnation server (RS) starts, and if necessary restarts, device drivers that are not loaded into memory at the same time as the kernel. In particular, if a driver fails during operation, the reincarnation server detects this failure, kills the driver if it is not already dead, and starts a fresh copy of the driver, making the system highly fault tolerant. |
| how OS hide hardware complexities from the users | Put a layer of software on top of the bare hardware, to manage all parts of the system, and present the user with an interface or virtual machine that is easier to understand and program. This layer of software is the operating system. |
| designers of OS try to keep kernel size small, comment | Small kernel size is important because kernel bugs are far more devastating than bugs in user-mode programs and more code means more bugs. |
| d. server process and driver process run in user mode | Server process and device driver provide very useful service to user if they in kernel mode its may damge the system. Device drivers runs in user mode: Allowed to request that the system task read data from or write data to I/O ports. Maybe also make other kernel calls. |
| Starting minix 3 using disk,hard disk drive and cd | CD-ROM is an exact copy of a bootable floppy disk, which is placed in memory and used as a RAM disk. After this first step control is transferred to the RAM disk and booting continues exactly as if a physical floppy disk were the boot device the hardware reads the first sector of the first track of the boot disk into memory and executes the code it finds there. On a diskette this sector contains the bootstrap program.The MINIX 3 bootstrap loads a larger program, boot, which then loads the operating system itself. A hard disk is divided into partitions, and the first sector of a hard disk contains a small program and the disk's partition table. Collectively these two pieces are called the master boot record. The program part is executed to read the partition table and to select the active partition. |
| notify and other three primitives. | A notify is nonblocking, which means the sender continues to execute whether or not the recipient is waiting. Because it does not block, a notification avoids the possibility of a message deadlock. |
| compare between layer 1 and layer 2,3 and 4 | layer 1,2,3 : usermode layer 4: kernel as much as you go up the privilege decrease and each layer depend on the layer down of it when start minix 3 the system will start from layer 1 then layer2 then layer3 then layer4 shutdown the reverse user cant contact with kernel but kernel can contact with every thing |
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