Incompatible pointer type warning in os161

Question

I am implementing a fork system call in os161 kernel. I am trying to create a new process and for its thread creation I used thread_fork. I am using the function md_forkentry to allocate heap and stack to the trapframe of the new thread and switch to user mode; but I get this warning after compiling the code: passing arg 4 of 'thread_fork' from incompatible pointer type

//Function Prototypes
int thread_fork(const char* name,void* data1,unsgined long data2,void (*func) (void*,unsigned long),struct thread **ret)
void md_forkentry(struct trapframe* tf,unsigned long n);

//the code 
struct trapframe* tf;
struct thread* child_thread;
//line I get the error from
int result=thread_fork("Child Process",(void*) tf,0,&md_forkentry,&child_thread);

score 0 · Accepted Answer · answered Mar 13 '20 at 23:31

Your prototype for md_forkentry() does not match the type of the 4th parameter of thread_fork().

md_forkentry() must be prototyped as:

void md_forkentry(void *, unsigned long);

(or vice-versa, i.e. fix the parameter type given in the prototype for thread_fork() if necessary)

Incompatible pointer type warning in os161

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