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From: minixug!root@nluug.nl (The Master)
Newsgroups: comp.os.minix
Subject: mem_copy problem in MM
Message-ID: <21169@nigel.udel.EDU>
Date: 6 Jun 90 04:19:53 GMT
Sender: mmdf@udel.EDU
Lines: 47

Hi!

I have a problem, and I don't know what I am doing wrong
here.  Thus, it is probably some very obvious error...

In MM, I have a structure of data, say:

PUBLIC struct testdata testdata;

Now, I add a system call with format m1, which has a
pointer to a similar structure in user space.  The
ptr is in m1_p1.

To copy the MM version of the data to the address in
user space, I can use the following code:

  vir_bytes src, dst;
  int len, r;

  /* Get the SRC and DST addresses right. */
  src = (vir_bytes) &testdada;
  dst = (vir_bytes) mm_in.m1_p1;
  len = sizeof(struct testdata);
  r = mem_copy(MM_PROC_NR, D, (long) src, who, D, (long) dst, (long) len);
  return(r);

Now, when I call this system call with the function:

#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <lib.h>


int testit(bufp)
struct testdata *bufp;
{
  int st;

  st = callm1(MM, TESTCALL, 0, 0, 0, bufp, NIL_PTR, NIL_PTR);
  return(st);
}

I get the result "-1", and perror() says "Invalid argument" .

Does anyone know what is going on here?  It is driving me up
the wall!