Add support for executing the FreeBSD 1/i386 a.out binaries on amd64.

In particular:
- implement compat shims for old stat(2) variants and ogetdirentries(2);
- implement delivery of signals with ancient stack frame layout and
  corresponding sigreturn(2);
- implement old getpagesize(2);
- provide a user-mode trampoline and LDT call gate for lcall $7,$0;
- port a.out image activator and connect it to the build as a module
  on amd64.

The changes are hidden under COMPAT_43.

MFC after:   1 month

2 files changed, 20 insertions, 0 deletions

diff --git a/sys/ia64/ia32/ia32_misc.c b/sys/ia64/ia32/ia32_misc.c
index c85e31d..148e31a 100644
--- a/sys/ia64/ia32/ia32_misc.c
+++ b/sys/ia64/ia32/ia32_misc.c
@@ -48,3 +48,14 @@ freebsd32_sysarch(struct thread *td, struct freebsd32_sysarch_args *uap)
 
 	return (EOPNOTSUPP);
 }
+
+#ifdef COMPAT_43
+int
+ofreebsd32_getpagesize(struct thread *td,
+    struct ofreebsd32_getpagesize_args *uap)
+{
+
+	td->td_retval[0] = IA32_PAGE_SIZE;
+	return (0);
+}
+#endif
diff --git a/sys/ia64/ia32/ia32_signal.c b/sys/ia64/ia32/ia32_signal.c
index e41f0af..b8dab90 100644
--- a/sys/ia64/ia32/ia32_signal.c
+++ b/sys/ia64/ia32/ia32_signal.c
@@ -92,6 +92,15 @@ x) */
 };
 int sz_ia32_sigcode = sizeof(ia32_sigcode);
 
+#ifdef COMPAT_43
+int
+ofreebsd32_sigreturn(struct thread *td, struct ofreebsd32_sigreturn_args *uap)
+{
+
+	return (EOPNOTSUPP);
+}
+#endif
+
 /*
  * Signal sending has not been implemented on ia64.  This causes
  * the sigtramp code to not understand the arguments and the application