From 9aecf50da5ff4a6f6ab62fccac0010bf9519b8b2 Mon Sep 17 00:00:00 2001
From: Michael Meissner <gnu@the-meissners.org>
Date: Mon, 12 Aug 1996 23:06:21 +0000
Subject: [PATCH] Test whether /dev/zero works before attemping to us it

---
 sim/ppc/ChangeLog    | 14 ++++++++++++++
 sim/ppc/Makefile.in  |  4 +++-
 sim/ppc/configure.in | 28 ++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/sim/ppc/ChangeLog b/sim/ppc/ChangeLog
index e67bdfe995..add31b5ff5 100644
--- a/sim/ppc/ChangeLog
+++ b/sim/ppc/ChangeLog
@@ -1,3 +1,17 @@
+Mon Aug 12 18:42:37 1996  Michael Meissner  <meissner@tiktok.cygnus.com>
+
+	* configure.in: Test whether /dev/zero works on the system, and if
+	it does, define HAVE_DEVZERO.
+	* configure: Regenerate.
+
+	* emul_generic.c (emul_add_tree_hardware): Do not add /iobus/disk
+	if we don't have a working /dev/zero on the system.
+
+	* emul_bugapi.c (emul_bugapi_init): If HAVE_DEVZERO is not
+	defined, don't add disk support.
+	(emul_bugapi_do_diskio): Ditto.
+	(emul_bugapi_instruction_call): Ditto.
+
 Wed Aug  7 14:34:20 1996  Michael Meissner  <meissner@tiktok.cygnus.com>
 
 	* emul_unix.c (HAVE_TCGETATTR): If HAVE_TERMIOS_STRUCTURE is not
diff --git a/sim/ppc/Makefile.in b/sim/ppc/Makefile.in
index 5ab3c22149..1d36f655f7 100644
--- a/sim/ppc/Makefile.in
+++ b/sim/ppc/Makefile.in
@@ -88,6 +88,7 @@ MODEL_CFLAGS = @sim_model@ @sim_default_model@ @sim_model_issue@
 STDIO_CFLAGS = @sim_stdio@
 TERMIO_CFLAGS = @sim_termio@
 WARNING_CFLAGS = @sim_warnings@
+DEVZERO_CFLAGS = @sim_devzero@
 CONFIG_CFLAGS = $(BSWAP_CFLAGS) \
   $(ENDIAN_CFLAGS) \
   $(REGPARM_CFLAGS) \
@@ -107,7 +108,8 @@ CONFIG_CFLAGS = $(BSWAP_CFLAGS) \
   $(MONITOR_CFLAGS) \
   $(MODEL_CFLAGS) \
   $(STDIO_CFLAGS) \
-  $(TERMIO_CFLAGS)
+  $(TERMIO_CFLAGS) \
+  $(DEVZERO_CFLAGS)
 
 STD_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(WARNING_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES)
 NOWARN_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES)
diff --git a/sim/ppc/configure.in b/sim/ppc/configure.in
index 1314a9340d..4924f78b7f 100644
--- a/sim/ppc/configure.in
+++ b/sim/ppc/configure.in
@@ -593,6 +593,33 @@ else
   ac_cv_termio_cline=no
 fi
 
+dnl Figure out if /dev/zero exists or not
+sim_devzero=""
+AC_MSG_CHECKING(for /dev/zero)
+AC_CACHE_VAL(ac_cv_devzero,
+[AC_TRY_RUN([#include <fcntl.h>
+main () {
+  char buf[2048];
+  int i;
+  int fd = open ("/dev/zero", O_RDONLY);
+  if (fd < 0)
+    return 1;
+  for (i = 0; i < sizeof (buf); i++)
+    buf[i] = 1;
+  if (read (fd, buf, sizeof (buf)) != sizeof (buf))
+    return 1;
+  for (i = 0; i < sizeof (buf); i++)
+    if (buf[i])
+      return 1;
+  return 0;
+}],[ac_cv_devzero=yes],[ac_cv_devzero=no],[ac_cv_devzero=no])])
+AC_MSG_RESULT($ac_cv_devzero)
+if test $ac_cv_devzero = yes; then
+  sim_devzero="-DHAVE_DEVZERO"
+else
+  sim_devzero=""
+fi
+
 AC_SUBST(CC_FOR_BUILD)
 AC_SUBST(CFLAGS)
 AC_SUBST(HDEFINES)
@@ -637,6 +664,7 @@ AC_SUBST(sim_default_model)
 AC_SUBST(sim_model_issue)
 AC_SUBST(sim_stdio)
 AC_SUBST(sim_termio)
+AC_SUBST(sim_devzero)
 
 AC_OUTPUT(Makefile,
 [case x$CONFIG_HEADERS in xconfig.h:config.in) echo > stamp-h ;; esac])
-- 
2.34.1