[src/trunk]: src/sys/arch/sun2/sun2 Now, instead of swapping in and out the P...

[fredette <fredette%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3db83fd912c0
branches:  trunk
changeset: 509853:3db83fd912c0
user:      fredette <fredette%NetBSD.org@localhost>
date:      Mon May 14 15:12:39 2001 +0000

description:
Now, instead of swapping in and out the PROM's segment zero,
swap in and out the mappings for virtual pages zero through three,
which are what the PROM really uses.  This is tied to the
move to ELF and the low memory usage changes.

diffstat:

 sys/arch/sun2/sun2/promlib.c |  59 +++++++++++++++++++++++++++++--------------
 1 files changed, 40 insertions(+), 19 deletions(-)

diffs (123 lines):

diff -r b3296a7c7f61 -r 3db83fd912c0 sys/arch/sun2/sun2/promlib.c
--- a/sys/arch/sun2/sun2/promlib.c      Mon May 14 15:07:23 2001 +0000
+++ b/sys/arch/sun2/sun2/promlib.c      Mon May 14 15:12:39 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: promlib.c,v 1.2 2001/04/10 12:40:53 fredette Exp $     */
+/*     $NetBSD: promlib.c,v 1.3 2001/05/14 15:12:39 fredette Exp $     */
 
 /*-
  * Copyright (c) 1996 The NetBSD Foundation, Inc.
@@ -48,6 +48,7 @@
 #include <sun2/sun2/machdep.h>
 #include <sun2/sun2/control.h>
 #include <sun2/sun2/vector.h>
+#include <machine/pte.h>
 
 /*
  * The state we save when we get ready to disappear into the PROM.
@@ -55,24 +56,41 @@
 struct kernel_state {
        int saved_spl;
        int saved_ctx;
-       int saved_pmeg;
+       u_int saved_ptes[4];
 };
 
 static void **sunmon_vbr;
 static struct kernel_state sunmon_kernel_state;
 static struct bootparam sunmon_bootparam;
+static u_int sunmon_ptes[4];
 
 static void tracedump __P((int));
 
 /*
  * The PROM keeps its data is in the first four physical pages, and
- * assumes that they're mapped to the first four virtual pages (i.e.,
- * segment zero).  Normally we keep segment zero either unmapped or
- * mapped to something else entirely, so before we can dereference
- * pointers in romVectorPtr or call the PROM, we have to set up its
- * mapping.  The pmeg to use is the same one used to map KERNBASE,
- * since KERNBASE points to the first four physical pages.
+ * assumes that they're mapped to the first four virtual pages.
+ * Normally we keep the first four virtual pages unmapped, so before
+ * we can dereference pointers in romVectorPtr or call the PROM, we 
+ * have to restore its mappings.  
+ */
+
+/*
+ * This swaps out one set of PTEs for the first 
+ * four virtual pages, and swaps another set in.
  */
+static inline void _prom_swap_ptes __P((u_int *, u_int *));
+static inline void
+_prom_swap_ptes(swapout, swapin)
+       u_int *swapout, *swapin;
+{
+       int pte_number;
+       vm_offset_t va;
+
+       for(pte_number = 0, va = 0; pte_number < 4; pte_number++, va += NBPG) {
+               swapout[pte_number] = get_pte(va);
+               set_pte(va, swapin[pte_number]);
+       }
+}
 
 /*
  * Prepare for running the PROM monitor.
@@ -84,13 +102,13 @@
        int full;
 {
        /*
-        * Save the current context, and the PMEG for segment
-        * zero, and reset them to what the PROM expects.
+        * Save the current context, and the PTEs for pages
+        * zero through three, and reset them to what the PROM 
+        * expects.
         */
        state->saved_ctx = get_context();
        set_context(0);
-       state->saved_pmeg = get_segmap(0);
-       set_segmap(0, get_segmap(KERNBASE));
+       _prom_swap_ptes(state->saved_ptes, sunmon_ptes);
 
        /*
         * If we're going to enter the PROM fully, raise the interrupt
@@ -126,10 +144,10 @@
        }
 
        /*
-        * Restore our PMEG for segment zero, and restore
-        * the current context.
+        * Restore our PTEs for pages zero through three, 
+        * and restore the current context.
         */
-       set_segmap(0, state->saved_pmeg);
+       _prom_swap_ptes(sunmon_ptes, state->saved_ptes);
        set_context(state->saved_ctx);
 }
 
@@ -348,10 +366,10 @@
 
        /*
         * Any second the pointers in the PROM vector are going to
-        * break (since they point into segment zero, which we like to
-        * keep unmapped), so we grab a complete copy of the
-        * bootparams, taking care to adjust the pointers in the copy
-        * to also point to the copy.
+        * break (since they point into pages zero through three, 
+        * which we like to keep unmapped), so we grab a complete 
+        * copy of the bootparams, taking care to adjust the pointers 
+        * in the copy to also point to the copy.
         */
        old_bp = *romVectorPtr->bootParam;
        new_bp = &sunmon_bootparam;
@@ -362,6 +380,9 @@
        }
        new_bp->fileName += bp_shift;
 
+       /* Save the PROM's mappings for pages zero through three. */
+       _prom_swap_ptes(sunmon_ptes, sunmon_ptes);
+
        /* Save the PROM monitor Vector Base Register (VBR). */
        sunmon_vbr = getvbr();