[xv6] adventure

Build & Startup

Every change has to be (re)built by

• make

Run the xv6 OS (without pop-up) by

• make qemu-nox

Or in debug mode by (cover elsewhere)

• make qemu-nox-gdb

Add Command

says, there is sample.c to be a command in xv6

• system call required?
• vi defs.h     (add forward declaration)



// proc.c
......
int             csc ( void ); 

• vi proc.c     (add function to this)

//custom process named "csc()"intcsc(){......}

• vi syscall.h  (define sys call vector)

// System call numbers #define SYS_fork    1 ......#define SYS_close  21 #define SYS_csc    22

• vi syscall.c  (connect shell and kernel by extern)

extern int sys_chdir(void);
......
extern int sys_csc(void);
......
static int (*syscalls[])(void) = {
......
[SYS_csc]     sys_csc,
};    

• vi user.h     (callable function via shell)

// system calls
......
int csc ( void );

• vi sysproc.c  (implement the method)

......
int
sys_csc ( void )
{
  return csc ();
} 

• vi usys.S     (marco to connect user call to sys call)

......SYSCALL(csc)

• vi sysfunc.h  (add sys call handler)
• put sample.c into xv6 folder

#include "types.h"......intmain(int argc, char *argv[]){  csc();  exit();}

• vi Makefile

UPROGS=\
        _cat\
        ......
        _sample\
        ......
......
EXTRA=\
        ......
        ln.c ...... sample.c ......\
        ......

• make              (Build the whole OS)

1. 
   
2. aas

Add Executable

says, step by step

• prepare C++ codes and header files
• vi example.cpp     (function)

using namespace std;
double example(double a, double b){
  return a + b;
}

• vi plus.h

#ifndef A_Hdouble example(double a, double b);#endif

• vi main.cpp    (main program)

#include <iostream>#include <stdlib.h>#include "plus.h"using namespace std;int main(int argc, char *argv[0]){  double x, y;  x = atof(argv[1]);  y = atof(argv[2]);  cout << plus(x, y) << endl;  return 0;}

• compile the codes to objects (plus.o & main.o)
• g++ -c example.cpp
• g++ -c main.cpp
• link objects to executable (plus)
• g++ -o plus example.o main.o
• execute it
• ./plus

Or, in one go

• create a Makefile
• vi Makefile

# default targetplus: example.o main.o        # target: prerequistites/dependencies        g++ -o plus example.o main.oexample.o main.o:             # prerequistites/dependencies:        g++ -c example.cpp        g++ -c main.cppclean:                        # other target        rm example.o main.o plus

Or with marco constantPROG   = plusSRCS   = example.cpp main.cppOBJS   = $(SRCS:.cpp=.o)      # replace .o to .cpp in SRCS# default target$(PROG): $(OBJS)              # target: prerequistites/dependencies        g++ -o $@ $(OBJS)$(OBJS):                      # prerequistites/dependencies:        g++ -c $*.cppclean:                        # other target        rm $(OBJS) $(PROG)

• simply use either
• make
• make plus
• to remove generated files
• make clean

g++ -o aShell aShell.cpp