It turns out that the reason for the difference between NetBSD and linux 
is that on linux, structures are, by default, aligned to a 32-bit 
boundary, even if they are composed solely of elements with less alignment 
than that.  On netbsd, structures are aligned to a byte boundary if no 
field within the structure requires a larger alignement.  Hence

#pragma pack(1)

struct test {
  int a,b;
};

#pragma pack()

is equivalent to writing

struct test {
  int a,b __attribute__((packed));
}


If you really want to force the structures to be internally packed, but 
word aligned, you will have to change the code to


#pragma pack(1)

struct test {
  int a,b;
} __attribute__((aligned(32)));

#pragma pack()


But for the above case, there then seems little point in using the packed 
pragma in the first place.

R.