Non-gcc compilers

[Matthew Dillon]

:I think on -current we have another possibility to do what my ntp patch 
:does. I think I remember a commit log which allows to add clock drivers 
:with a make.conf variable, but I was lazy at that time and forgot to 
:investigate if my patch is still needed instead of adding it to 
:make.conf. The code for this clock driver wasn't added, as there where 
:some issues with the in kernel code, I don't remember which issues, as I 
:haven't encountered any problems, but the discussion should be available 
:in -current.

    I don't consider it a big deal.  As long as it doesn't break anything
    there is no particular reason not to compile it in.

:This patch is from a mail from bde, see 
:http://www.leidinger.net/FreeBSD/misc-patches/kern_exec.c.patch for more 
:(it's the mail itself).
:
:>     Also, newer gcc's use a masking operation on %esp instead of a subtract
:>     and do not actually need an aligned stack pointer to be optimal.  But
:>     it doesn't hurt so I will commit it anyway :-)
:
:Feel free to send me a diff of your version.
:
:Bye,
:Alexander.

    I committed it.  Patch (again DFly) attached.  I will email BDE to make
    sure that the '- 4' is not needed.  Basically I just used the patch you
    had listed and cleaned it up a bit and removed the - 4.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>

Index: kern_exec.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_exec.c,v
retrieving revision 1.15
retrieving revision 1.16
diff -u -r1.15 -r1.16
--- kern_exec.c	16 Nov 2003 02:37:39 -0000	1.15
+++ kern_exec.c	16 Nov 2003 19:32:31 -0000	1.16
@@ -24,7 +24,7 @@
  * SUCH DAMAGE.
  *
  * $FreeBSD: src/sys/kern/kern_exec.c,v 1.107.2.15 2002/07/30 15:40:46 nectar Exp $
- * $DragonFly: src/sys/kern/kern_exec.c,v 1.15 2003/11/16 02:37:39 dillon Exp $
+ * $DragonFly: src/sys/kern/kern_exec.c,v 1.16 2003/11/16 19:32:31 dillon Exp $
  */
 
 #include <sys/param.h>
@@ -753,23 +753,26 @@
 	/*
 	 * If we have a valid auxargs ptr, prepare some room
 	 * on the stack.
-	 */
-	if (imgp->auxargs)
-	/*
+	 *
 	 * The '+ 2' is for the null pointers at the end of each of the
 	 * arg and env vector sets, and 'AT_COUNT*2' is room for the
 	 * ELF Auxargs data.
 	 */
+	if (imgp->auxargs) {
+		vectp = (char **)(destp - (imgp->args->argc +
+			imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*));
+	} else {
 		vectp = (char **)(destp - (imgp->args->argc +
-		    imgp->args->envc + 2 + AT_COUNT*2) * sizeof(char*));
-	else 
+			imgp->args->envc + 2) * sizeof(char*));
+	}
+
 	/*
-	 * The '+ 2' is for the null pointers at the end of each of the
-	 * arg and env vector sets
+	 * Align the stack to a multiple of 0x20 to be friendly to high-end
+	 * cpus.  This is not strictly necessary since newer gcc's now use
+	 * a masking operation on the stack pointer instead of assuming
+	 * alignment, but it doesn't hurt either.
 	 */
-		vectp = (char **)
-		    (destp - (imgp->args->argc + imgp->args->envc + 2) *
-		    sizeof(char*));
+	vectp = (char **)((vm_offset_t)vectp & ~(vm_offset_t)0x1F);
 
 	/*
 	 * vectp also becomes our initial stack base