68000flat: don't push unneeded pid return word onto switch stacks

diff --git a/Kernel/lib/68000flat.S b/Kernel/lib/68000flat.S
index 3740eca..9f1f0b3 100644 (file)
--- a/Kernel/lib/68000flat.S
+++ b/Kernel/lib/68000flat.S
@@ -13,9 +13,6 @@ platform_switchout:
         or #$0700,sr
         ; save machine state
 
-        clr.w -(sp) ; return code set here is ignored, but switchin can
-        ; return from either switchout OR dofork, so they must both write
-        ; U_DATA__U_SP with the following on the stack:
        move.l usp,a0
        movem.l a0/a2-a4/a6/d2-d7,-(sp)
        move.l sp,U_DATA__U_SP(a5)      ; this is where the SP is restored in switchin
@@ -58,9 +55,7 @@ switchin:
        ; recover the task switch state
        movem.l (sp)+,a0/a2-a4/a6/d2-d7
        move.l a0,USP
-       ; and return code - FIXME: we have a different fork path so the d0
-       ; stacking can go
-       move.w (sp)+,d0
+       clr.w d0
 
         tst.b U_DATA__U_ININTERRUPT(a5)
         bne keepoff ; in ISR, leave interrupts off
@@ -150,7 +145,6 @@ loop:
        ;
        ; And a frame as if we did a switchout
        ;
-       move.w #0,-(a1)
        movem.l a0/a2-a4/a6/d2-d7,-(a1)
        move.l a1,U_DATA__U_SP(a2)      ; Set the stack pointer
 
@@ -167,19 +161,20 @@ forked_up:
 ;
 forkreturn:
        ; Wipe any stray kernel data
+       moveq #0,d0
        moveq #0,d1
-       move.l d1,a0
-       move.l d1,a1
-       move.l d1,a2
-       move.l d1,a3
-       move.l d1,a4
-       move.l d1,a6
-       move.l d1,d2
-       move.l d1,d3
-       move.l d1,d4
-       move.l d1,d5
-       move.l d1,d6
-       move.l d1,d7
+       moveq #0,d2
+       moveq #0,d3
+       moveq #0,d4
+       moveq #0,d5
+       moveq #0,d6
+       moveq #0,d7
+       move.l d0,a0
+       move.l d0,a1
+       move.l d0,a2
+       move.l d0,a3
+       move.l d0,a4
+       move.l d0,a6
        ; recover A5 to match the parent
        move.l (sp)+,a5
        ; and RTE to the same address (which is fine as the user memory