re: COMPAT_50 vs NET_RT_IFLIST

[Paul Goyette <paul%whooppee.com@localhost>]

Alas, making the suggested changes does not help.  Same results as
before:

Userland and Kernel both -current with suggested changes (the diffs
are attached to this Email):

	# ifconfig -l
	wm0 lo0
	# ifconfig lo0
	lo0: flags=0x8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33624
	        inet 127.0.0.1/8 flags 0x0
	        inet6 ::1/128 flags 0x20<NODAD>
	        inet6 fe80::1%lo0/64 flags 0x0 scopeid 0x2
	#


And with a 5.2 base system loaded in /chroot52 directory:

	# chroot /chroot52 ifconfig -l

	# chroot /chroot52 ifconfig lo0

	#


On Mon, 29 Apr 2019, matthew green wrote:

> > I still cannot explain how things got broken between 5.2 and 8.0.  I
> > will defer to those who are more expert in this area than am I.  My
> > suspicion is that the breakage is related to sys/socket.h rev 1.99
> > which versioned AF_{,O}ROUTE for some 64-bit cleanliness.
>
> i think i have a guess about the problem.
>
> sys/net/if.h, sys/net/route.h, and sys/compat/net/if.h all
> have this code:
>
> /*
> * Message format for use in obtaining information about interfaces from
> * sysctl and the routing socket.  We need to force 64-bit alignment if we
> * aren't using compatiblity definitons.
> */
> #if !defined(_KERNEL) || !defined(COMPAT_RTSOCK)
> #define __align64       __aligned(sizeof(uint64_t))
> #else
> #define __align64
> #endif
> struct if_msghdr {
>        u_short ifm_msglen __align64;
>
> but i think this comment is wrong.
>
> the compat structures are defined in the compat headers and
> the above structure should never change, however when the
> code handling code wants to talk to the *real* structure it
> will get this adjusted one (without the align), and thus
> it will copy the wrong portions out from it.
>
> the fix may be as simple as removing this from these headers
> (leaving it always defined for the current defs), and making
> sure that the compat headers have the right alignment (my
> quick look seem ok.)
>
> this will, obviously, need a recompile of the newer kernel.
>
>
> .mrg.
>
> !DSPAM:5cc6a3b33697082216442!

+--------------------+--------------------------+-----------------------+
| Paul Goyette       | PGP Key fingerprint:     | E-mail addresses:     |
| (Retired)          | FA29 0E3B 35AF E8AE 6651 | paul%whooppee.com@localhost     |
| Software Developer | 0786 F758 55DE 53BA 7731 | pgoyette%netbsd.org@localhost   |
+--------------------+--------------------------+-----------------------+

Index: if.h
===================================================================
RCS file: /cvsroot/src/sys/net/if.h,v
retrieving revision 1.269
diff -u -p -r1.269 if.h
--- if.h	23 Mar 2019 09:48:04 -0000	1.269
+++ if.h	29 Apr 2019 11:34:55 -0000
@@ -737,14 +737,10 @@ struct ifaddr {
 
 /*
  * Message format for use in obtaining information about interfaces from
- * sysctl and the routing socket.  We need to force 64-bit alignment if we
- * aren't using compatiblity definitons.
+ * sysctl and the routing socket.  We need to force 64-bit alignment.
  */
-#if !defined(_KERNEL) || !defined(COMPAT_RTSOCK)
 #define	__align64	__aligned(sizeof(uint64_t))
-#else
-#define	__align64
-#endif
+
 struct if_msghdr {
 	u_short	ifm_msglen __align64;
 				/* to skip over non-understood messages */
Index: route.h
===================================================================
RCS file: /cvsroot/src/sys/net/route.h,v
retrieving revision 1.121
diff -u -p -r1.121 route.h
--- route.h	29 Apr 2019 05:42:09 -0000	1.121
+++ route.h	29 Apr 2019 11:34:55 -0000
@@ -204,16 +204,11 @@ struct	rtstat {
  * at a 64-bit boundary, we also force the size to be a multiple of 64-bits.
  */
 
-#if !defined(_KERNEL) || !defined(COMPAT_RTSOCK)
 /*
- * If we aren't being compiled for backwards compatiblity, enforce 64-bit
- * alignment so any routing message is the same regardless if the kernel
- * is an ILP32 or LP64 kernel.
+ * Enforce 64-bit alignment so any routing message is the same regardless
+ * if the kernel is an ILP32 or LP64 kernel.
  */
 #define	__align64	__aligned(sizeof(uint64_t))
-#else
-#define	__align64
-#endif
 
 struct rt_msghdr {
 	u_short	rtm_msglen __align64;