The mobile communication terminal 1 calls the selected call destination according to an application program (program). A call is made through a telephone network N2 by means of mobile communication between the mobile communication terminal 1 and a phone at the call destination, and the call charge...
/kernel/exec.c...更新页表,内存等操作// Save program name for debugging.for(last=s=path;*s;s++)if(*s=='/')last=s+1;safestrcpy(p->name,last,sizeof(p->name));// Commit to the user image.oldpagetable=p->pagetable;p->pagetable=pagetable;p->sz=sz;p->trapframe->epc=elf.entr...
For example, to trace the fork system call, a program calls trace(1 << SYS_fork), where SYS_fork is a syscall number from kernel/syscall.h. You have to modify the xv6 kernel to print out a line when each system call is about to return, if the system call’s number is set in ...
The segment is locked and cannot be reallocated. ERROR_TOO_MANY_MODULES 214 (0xD6) Too many dynamic-link modules are attached to this program or dynamic-link module. ERROR_NESTING_NOT_ALLOWED 215 (0xD7) Cannot nest calls to LoadModule. ...
is not even.staticintHalf(intinput){if( input %2!=0)thrownewException( );elsereturninput /2; }// Half2 throws a derived exception if the input is not even.staticintHalf2(intinput){if( input %2!=0)thrownewNotEvenException( );elsereturninput /2; }// CalcHalf calls Half and ...
(5,5,"SemaphoreExample3");// Attempt to enter the semaphore three times. If another// copy of this program is already running, only the first// two requests can be satisfied. The third blocks. Note// that in a real application, timeouts should be used// on the WaitOne calls, to ...
status= system(command)calls the operating system to execute the specified command. The operation waits for the command to finish execution before returning the exit status of the command to thestatusvariable. The function starts a new cmd/shell process, executescommand, exits the process, and ret...
There are three cornerstones of system programming in Linux: system calls, the C library, and the C compiler. Each deserves an introduction. System Calls System programming starts and ends with system calls. System calls (often shortened to syscalls) are function invocations made from user space—...
(5,5,"SemaphoreExample3");// Attempt to enter the semaphore three times. If another// copy of this program is already running, only the first// two requests can be satisfied. The third blocks. Note// that in a real application, timeouts should be used// on the WaitOne calls, to ...
Program terminated Example 10–6 Bringing a Stand-Alone System to Run Level 0 In this example, theinitcommand is used to bring an x86 based stand-alone system to the level where it is safe to turn off power. #init 0# INIT: New run level: 0 ...