From d069c9b486d2a2b9b26294023dd397f366d5e5ba Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sat, 15 Nov 2014 15:21:24 +0100
Subject: pc: get rid of fixed 8MB memory map (now dynamically between 4 to 16
 MB depending on kernel size)

we now do mapping of KZERO to ROUND(end, 4*MB) where
end needs not to be above 16MB. this allows for bigger
kernels.
---
 sys/src/9/pc/l.s      | 47 +++++++++++++++++++++++------------------------
 sys/src/9/pc/mem.h    | 12 +++++++-----
 sys/src/9/pc/memory.c |  3 ++-
 3 files changed, 32 insertions(+), 30 deletions(-)

diff --git a/sys/src/9/pc/l.s b/sys/src/9/pc/l.s
index 663107e7a..661e66422 100644
--- a/sys/src/9/pc/l.s
+++ b/sys/src/9/pc/l.s
@@ -162,46 +162,45 @@ TEXT m0idtptr(SB), $0
 TEXT mode32bit(SB), $0
 	/* At this point, the GDT setup is done. */
 
-	MOVL	$PADDR(CPU0PDB), DI		/* clear 4 pages for the tables etc. */
+	MOVL	$((CPU0END-CPU0PDB)>>2), CX
+	MOVL	$PADDR(CPU0PDB), DI
 	XORL	AX, AX
-	MOVL	$(4*BY2PG), CX
-	SHRL	$2, CX
 
 	CLD
 	REP;	STOSL
 
+	MOVL	$PADDR(CPU0PTE), DX
+	MOVL	$(PTEWRITE|PTEVALID), BX	/* page permissions */
+	ORL	BX, DX
+
 	MOVL	$PADDR(CPU0PDB), AX
 	ADDL	$PDO(KZERO), AX			/* page directory offset for KZERO */
-	MOVL	$PADDR(CPU0PTE), (AX)		/* PTE's for KZERO */
-	MOVL	$(PTEWRITE|PTEVALID), BX	/* page permissions */
-	ORL	BX, (AX)
 
-	ADDL	$4, AX
-	MOVL	$PADDR(CPU0PTE1), (AX)		/* PTE's for KZERO+4MB */
-	MOVL	$(PTEWRITE|PTEVALID), BX	/* page permissions */
-	ORL	BX, (AX)
+	MOVL	DX, 0(AX)			/* PTE's for KZERO */
+	ADDL	$BY2PG, DX
+	MOVL	DX, 4(AX)			/* PTE's for KZERO+4MB */
+	ADDL	$BY2PG, DX
+	MOVL	DX, 8(AX)			/* PTE's for KZERO+8MB */
+	ADDL	$BY2PG, DX
+	MOVL	DX, 12(AX)			/* PTE's for KZERO+12MB */
 
 	MOVL	$PADDR(CPU0PTE), AX		/* first page of page table */
-	MOVL	$1024, CX			/* 1024 pages in 4MB */
+	MOVL	$end-KZERO(SB), CX
+	ADDL	$(BY2XPG-1), CX
+	ANDL	$~(BY2XPG-1), CX		/* round to 4MB */
+	MOVL	CX, MemMin-KZERO(SB)		/* see memory.c */
+	SHRL	$PGSHIFT, CX
+	MOVL	BX, DX
 _setpte:
-	MOVL	BX, (AX)
-	ADDL	$(1<<PGSHIFT), BX
+	MOVL	DX, (AX)
+	ADDL	$BY2PG, DX
 	ADDL	$4, AX
 	LOOP	_setpte
 
-	MOVL	$PADDR(CPU0PTE1), AX		/* second page of page table */
-	MOVL	$1024, CX			/* 1024 pages in 4MB */
-_setpte1:
-	MOVL	BX, (AX)
-	ADDL	$(1<<PGSHIFT), BX
-	ADDL	$4, AX
-	LOOP	_setpte1
-
 	MOVL	$PADDR(CPU0PTE), AX
 	ADDL	$PTO(MACHADDR), AX		/* page table entry offset for MACHADDR */
-	MOVL	$PADDR(CPU0MACH), (AX)		/* PTE for Mach */
-	MOVL	$(PTEWRITE|PTEVALID), BX	/* page permissions */
-	ORL	BX, (AX)
+	ORL	$PADDR(CPU0MACH), BX
+	MOVL	BX, (AX)			/* PTE for Mach */
 
 /*
  * Now ready to use the new map. Make sure the processor options are what is wanted.
diff --git a/sys/src/9/pc/mem.h b/sys/src/9/pc/mem.h
index 79ab270d6..7f5b09a16 100644
--- a/sys/src/9/pc/mem.h
+++ b/sys/src/9/pc/mem.h
@@ -63,12 +63,14 @@
 #define	REBOOTADDR	(0x11000)		/* reboot code - physical address */
 #define	CPU0PDB		(KZERO+0x12000)		/* bootstrap processor PDB */
 #define	CPU0PTE		(KZERO+0x13000)		/* bootstrap processor PTE's for 0-4MB */
-#define	CPU0GDT		(KZERO+0x14000)		/* bootstrap processor GDT */
-#define	MACHADDR	(KZERO+0x15000)		/* as seen by current processor */
-#define	CPU0MACH	(KZERO+0x16000)		/* Mach for bootstrap processor */
+#define	CPU0PTE1	(KZERO+0x14000)		/* bootstrap processor PTE's for 4-8MB */
+#define	CPU0PTE2	(KZERO+0x15000)		/* bootstrap processor PTE's for 8-12MB */
+#define	CPU0PTE3	(KZERO+0x16000)		/* bootstrap processor PTE's for 12-16MB */
+#define	CPU0GDT		(KZERO+0x17000)		/* bootstrap processor GDT */
+#define	MACHADDR	(KZERO+0x18000)		/* as seen by current processor */
+#define	CPU0MACH	(KZERO+0x19000)		/* Mach for bootstrap processor */
 #define	MACHSIZE	BY2PG
-#define CPU0PTE1	(KZERO+0x17000)		/* bootstrap processor PTE's for 4MB-8MB */
-#define CPU0END		(CPU0PTE1+BY2PG)
+#define	CPU0END		(CPU0MACH+BY2PG)
 /*
  * N.B.  ramscan knows that CPU0END is the end of reserved data
  * N.B.  _startPADDR knows that CPU0PDB is the first reserved page
diff --git a/sys/src/9/pc/memory.c b/sys/src/9/pc/memory.c
index 5f2429265..acff53d10 100644
--- a/sys/src/9/pc/memory.c
+++ b/sys/src/9/pc/memory.c
@@ -15,6 +15,8 @@
 
 #define MEMDEBUG	0
 
+u32int MemMin = 8*MB;	/* set in l.s */
+
 enum {
 	MemUPA		= 0,		/* unbacked physical address */
 	MemRAM		= 1,		/* physical memory */
@@ -24,7 +26,6 @@ enum {
 
 	KB		= 1024,
 
-	MemMin		= 8*MB,
 	MemMax		= (3*1024+768)*MB,
 };
 
-- 
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