Re: Current kernel with http://gnats.netbsd.org/39965 and pmap patches

I wrote:

> I don't understand what XXX calculations in amiga_init.c do and
> how they map PA of Sysmap (Sysptmap_pa) into VM_MAX_KERNEL_ADDRESS
> in mmu040_setup() case... (it's a bit different from other m68k ports)

Is this what those calculations intend?
(though I'm still being confused a bit)


--- atari/atari_init.c.0	2008-12-17 19:12:51.000000000 +0900
+++ atari/atari_init.c	2008-12-18 02:22:18.000000000 +0900
@@ -959,15 +965,15 @@
 	u_int		sysptmap_pa;	/* System page table		*/
 	u_int		kbase;
 {
-	int		i;
+	int		num1, num2;
 	st_entry_t	sg_proto, *sg, *esg;
-	pt_entry_t	pg_proto;
+	pt_entry_t	pg_proto, *pg, *epg;
 
 	/*
 	 * First invalidate the entire "segment table" pages
 	 * (levels 1 and 2 have the same "invalid" values).
 	 */
-	sg  = (u_int *)Sysseg_pa;
+	sg  = (st_entry_t *)Sysseg_pa;
 	esg = &sg[kstsize * NPTEPG];
 	while (sg < esg)
 		*sg++ = SG_NV;
@@ -981,24 +987,24 @@
 	 * pages of PTEs.  Note that we set the "used" bit
 	 * now to save the HW the expense of doing it.
 	 */
-	i   = (ptsize >> PGSHIFT) * (NPTEPG / SG4_LEV3SIZE);
-	sg  = &((u_int *)Sysseg_pa)[SG4_LEV1SIZE];
-	esg = &sg[i];
+	num2 = (ptsize >> PGSHIFT) * (NPTEPG / SG4_LEV3SIZE);
+	sg  = &((st_entry_t *)Sysseg_pa)[SG4_LEV1SIZE];
+	esg = &sg[num2];
 	sg_proto = ((u_int)pt + kbase) | SG_U | SG_RW | SG_V;
 	while (sg < esg) {
 		*sg++     = sg_proto;
-		sg_proto += (SG4_LEV3SIZE * sizeof (st_entry_t));
+		sg_proto += (SG4_LEV3SIZE * sizeof(st_entry_t));
 	}
 
 	/*
 	 * Initialize level 1 descriptors.  We need:
-	 *	roundup(num, SG4_LEV2SIZE) / SG4_LEVEL2SIZE
-	 * level 1 descriptors to map the 'num' level 2's.
+	 *	roundup(num2, SG4_LEV2SIZE) / SG4_LEVEL2SIZE
+	 * level 1 descriptors to map the 'num2' level 2's.
 	 */
-	i = roundup(i, SG4_LEV2SIZE) / SG4_LEV2SIZE;
-	protostfree = (-1 << (i + 2)) /* & ~(-1 << MAXKL2SIZE) */;
+	num1 = roundup(num2, SG4_LEV2SIZE) / SG4_LEV2SIZE;
+	protostfree = (-1 << (num1 + 1)) /* & ~(-1 << MAXKL2SIZE) */;
 	sg  = (u_int *)Sysseg_pa;
-	esg = &sg[i];
+	esg = &sg[num1];
 	sg_proto = ((u_int)&sg[SG4_LEV1SIZE] + kbase) | SG_U | SG_RW |SG_V;
 	while (sg < esg) {
 		*sg++     = sg_proto;
@@ -1013,9 +1019,7 @@
 	/*
 	 * Kernel segment table at end of next level 2 table
 	 */
-	/* XXX fix calculations XXX */
-	i = ((((ptsize >> PGSHIFT) + 3) & -2) - 1) * (NPTEPG / SG4_LEV3SIZE);
-	sg = &((u_int *)Sysseg_pa)[SG4_LEV1SIZE + i];
+	sg = &((st_entry_t *)Sysseg_pa)[SG4_LEV1SIZE + num1 * SG4_LEV2SIZE];
 	esg = &sg[NPTEPG / SG4_LEV3SIZE];
 	sg_proto = sysptmap_pa | SG_U | SG_RW | SG_V;
 	while (sg < esg) {
@@ -1026,23 +1030,25 @@
 	/*
 	 * Initialize Sysptmap
 	 */
-	sg = (u_int *) sysptmap_pa;
-	esg = &sg[ptsize >> PGSHIFT];
+	pg = (pt_entry_t *) sysptmap_pa;
+	epg = &sg[ptsize >> PGSHIFT];
 	pg_proto = ((u_int)pt + kbase) | PG_RW | PG_CI | PG_V;
-	while (sg < esg) {
-		*sg++ = pg_proto;
+	while (pg < epg) {
+		*pg++ = pg_proto;
 		pg_proto += PAGE_SIZE;
 	}
 
 	/*
 	 * Invalidate rest of Sysptmap page
 	 */
-	esg = (u_int *)(sysptmap_pa + PAGE_SIZE - sizeof(st_entry_t));
-	while (sg < esg)
-		*sg++ = SG_NV;
-	sg = (u_int *) Sysptmap;
-	sg = &sg[256 - 1];              /* XXX */
-	*sg = sysptmap_pa | PG_RW | PG_CI | PG_V;
+	epg = (pt_entry_t *)(sysptmap_pa + (NPTEPG - 1) * sizeof(pt_entry_t));
+	while (pg < epg)
+		*pg++ = SG_NV;
+
+	/*
+	 * Initialize the last one to point to Sysptmap.
+	 */
+	*pg = sysptmap_pa | PG_RW | PG_CI | PG_V;
 }
 #endif /* M68040 */
 


---
Izumi Tsutsui