VxWorks example, setting up a write protected memory block

/* Must allocate on page boundry, so we use valloc quick n dirty */
/* Allocating in multiples of page boundry size, again quick n dirty */

char *vmPtr;

void barry_vm_alloc( void )
{
	vmPtr=valloc(4096);
	if( NULL == vmPtr )
		{
		printf("Cannot vm alloc\r\n");
		}
}

void barry_vm_set( int enable )
{
	vmBaseStateSet (NULL, vmPtr, 4096,
                    VM_STATE_MASK_WRITABLE,
                    (enable ? VM_STATE_WRITABLE_NOT : VM_STATE_WRITABLE));
}

void barry_vm_write( void )
{
	*vmPtr=123;
}

Fun with pthread

pthread_addr_t

/* Attributes for threads.  */
typedef struct __pthread_attr_s
{
  int __detachstate;
  int __schedpolicy;
  struct __sched_param __schedparam;
  int __inheritsched;
  int __scope;
  size_t __guardsize;
  int __stackaddr_set;
  void *__stackaddr;
  size_t __stacksize;
} pthread_attr_t;

#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

void* print_foo( void *ptr )
{
        printf("Thread!\r\n");
        pthread_exit(NULL);
}

void create_thread(void)
{
        pthread_t thread1;
        pthread_attr_t attr;
        int ireg=pthread_create(&thread1,NULL,print_foo,(void*)NULL);
        printf("Create thread = %d\r\n",ireg);
        // Comment out the next line to see the '12' error occur.
        pthread_detach( thread1 );
}

int main( int argc, char *argv[] )
{
        while(1)
        {
       // Force many threads to start, to create the error condition
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        create_thread();
        sleep(1);
        }
}

BSD rt_entry structure for route and arp routes

## ROUTE.H ##
struct rtentry {
	struct	radix_node rt_nodes[2];	/* tree glue, and other values */
#define	rt_key(r)	((struct sockaddr *)((r)->rt_nodes->rn_key))
#define	rt_mask(r)	((struct sockaddr *)((r)->rt_nodes->rn_mask))
	struct	sockaddr *rt_gateway;	/* value */
	short	rt_flags;		/* up/down?, host/net */
	short	rt_refcnt;		/* # held references */
	u_long	rt_use;			/* raw # packets forwarded */
	struct	ifnet *rt_ifp;		/* the answer: interface to use */
	struct	ifaddr *rt_ifa;		/* the answer: interface to use */
	struct	sockaddr *rt_genmask;	/* for generation of cloned routes */
	caddr_t	rt_llinfo;		/* pointer to link level info cache */
	struct	rtentry *rt_gwroute;	/* implied entry for gatewayed routes */
                int	rt_mod;			/* last modified XXX */ 
	struct	rt_metrics rt_rmx;	/* metrics used by rx'ing protocols */
        struct  rtentry *rt_parent;     /* parent of route (if cloned) */
};

## if_ether.h ##
arptab and llinfo_arp
struct	arptab {
	struct	in_addr at_iaddr;	/* internet address */
	u_char	at_enaddr[6];		/* ethernet address */
	u_char	at_timer;		/* minutes since last reference */
	u_char	at_flags;		/* flags */
	struct	mbuf *at_hold;		/* last packet until resolved/timeout */
} ETHER_PACKED;

struct llinfo_arp {
	struct	llinfo_arp *la_next;
	struct	llinfo_arp *la_prev;
	struct	rtentry *la_rt;
	struct	mbuf *la_hold;		/* last packet until resolved/timeout */
	long	la_asked;		/* last time we QUERIED for this addr */
#define la_timer la_rt->rt_rmx.rmx_expire /* deletion time in seconds */
} ETHER_PACKED;