Clean up memlayout.h

Get rid of last instances of linear address and "la"
Get ready for detecting physical memory dynamically

defs.h

@@ -66,6 +66,7 @@ char*           enter_alloc(void);
 char*           kalloc(void);
 void            kfree(char*);
 void            kinit(void);
+uint            detect_memory(void);
 
 // kbd.c
 void            kbdintr(void);

kalloc.c

@@ -19,7 +19,8 @@ struct {
 } kmem;
 
 extern char end[]; // first address after kernel loaded from ELF file
-char *newend;
+extern uint maxpa;        // Maximum physical address
+static char *newend;
 
 // simple page allocator to get off the ground during entry
 char *
@@ -36,6 +37,12 @@ enter_alloc(void)
   return p;
 }
 
+uint
+detect_memory(void)
+{
+  return 0xE000000;
+}
+
 // Initialize free list of physical pages.
 void
 kinit(void)
@@ -44,7 +51,7 @@ kinit(void)
 
   initlock(&kmem.lock, "kmem");
   p = (char*)PGROUNDUP((uint)newend);
-  for(; p + PGSIZE <= (char*)p2v(PHYSTOP); p += PGSIZE)
+  for(; p + PGSIZE <= (char*)p2v(maxpa); p += PGSIZE)
     kfree(p);
 }
 
@@ -58,7 +65,7 @@ kfree(char *v)
 {
   struct run *r;
 
-  if((uint)v % PGSIZE || v < end || v2p(v) >= PHYSTOP)
+  if((uint)v % PGSIZE || v < end || v2p(v) >= maxpa)
     panic("kfree");
 
   // Fill with junk to catch dangling refs.

lapic.c

@@ -135,7 +135,6 @@ microdelay(int us)
 // Start additional processor running entry code at addr.
 // See Appendix B of MultiProcessor Specification.
 void
-
 lapicstartap(uchar apicid, uint addr)
 {
   int i;
@@ -169,3 +168,5 @@ lapicstartap(uchar apicid, uint addr)
     microdelay(200);
   }
 }
+
+

memlayout.h

@@ -1,17 +1,12 @@
 // Memory layout
 
-#define PGSIZE          4096            // bytes mapped by a page
-#define PGSHIFT         12              // log2(PGSIZE)
-
-#define KSTKSIZE        (8*PGSIZE)              // size of a kernel stack
-
-#define DEVSPACE  0xFE000000  // other devices are in the top of the phys address space
-#define PHYSTOP   0xE000000 // use phys mem up to here as free pool
+#define EXTMEM  0x100000            // Start of extended memory
+#define DEVSPACE 0xFE000000         // Other devices are at high addresses
 
 // Key addresses for address space layout (see kmap in vm.c for the layout)
-#define KERNBASE 0xF0000000  // First kernel virtual address
+#define KERNBASE 0xF0000000         // First kernel virtual address
 #define USERTOP  (KERNBASE-PGSIZE)  // Highest user virtual address
-#define KERNLINK 0xF0100000   // Address where kernel is linked
+#define KERNLINK (KERNBASE+EXTMEM)  // Address where kernel is linked
 
 #ifndef __ASSEMBLER__
 

mmu.h

@@ -100,32 +100,34 @@ struct segdesc {
 #define STS_IG32    0xE     // 32-bit Interrupt Gate
 #define STS_TG32    0xF     // 32-bit Trap Gate
 
-// A linear address 'la' has a three-part structure as follows:
+// A virtual address 'la' has a three-part structure as follows:
 //
 // +--------10------+-------10-------+---------12----------+
 // | Page Directory |   Page Table   | Offset within Page  |
 // |      Index     |      Index     |                     |
 // +----------------+----------------+---------------------+
-//  \--- PDX(la) --/ \--- PTX(la) --/ 
+//  \--- PDX(va) --/ \--- PTX(va) --/ 
 
 // page directory index
-#define PDX(la)		(((uint)(la) >> PDXSHIFT) & 0x3FF)
+#define PDX(va)		(((uint)(va) >> PDXSHIFT) & 0x3FF)
 
 // page table index
-#define PTX(la)		(((uint)(la) >> PTXSHIFT) & 0x3FF)
+#define PTX(va)		(((uint)(va) >> PTXSHIFT) & 0x3FF)
 
-// construct linear address from indexes and offset
+// construct virtual address from indexes and offset
 #define PGADDR(d, t, o)	((uint)((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))
 
 // Page directory and page table constants.
 #define NPDENTRIES	1024		// page directory entries per page directory
 #define NPTENTRIES	1024		// page table entries per page table
+#define PGSIZE          4096            // bytes mapped by a page
 
+#define PGSHIFT         12              // log2(PGSIZE)
 #define PTXSHIFT	12		// offset of PTX in a linear address
 #define PDXSHIFT	22		// offset of PDX in a linear address
 
 #define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
-#define PGROUNDDOWN(a) ((char*)((((unsigned int)(a)) & ~(PGSIZE-1))))
+#define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1))
 
 // Page table/directory entry flags.
 #define PTE_P		0x001	// Present

vm.c

@@ -8,6 +8,7 @@
 #include "elf.h"
 
 extern char data[];  // defined in data.S
+uint maxpa;  // max physical address
 pde_t *kpgdir;  // for use in scheduler()
 struct segdesc gdt[NSEGS];
 
@@ -64,8 +65,8 @@ walkpgdir(pde_t *pgdir, const void *va, char* (*alloc)(void))
   return &pgtab[PTX(va)];
 }
 
-// Create PTEs for virtual addresses starting at la that refer to
-// physical addresses starting at pa. la and size might not
+// Create PTEs for virtual addresses starting at va that refer to
+// physical addresses starting at pa. va and size might not
 // be page-aligned.
 static int
 mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(void))
@@ -73,8 +74,8 @@ mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(vo
   char *a, *last;
   pte_t *pte;
   
-  a = PGROUNDDOWN(va);
-  last = PGROUNDDOWN(va + size - 1);
+  a = (char *) PGROUNDDOWN((uint) va);
+  last = (char *) PGROUNDDOWN(((uint) va) + size - 1);
   for(;;){
     pte = walkpgdir(pgdir, a, alloc);
     if(pte == 0)
@@ -100,13 +101,13 @@ mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(vo
 // 
 // setupkvm() and exec() set up every page table like this:
 //   0..USERTOP      : user memory (text, data, stack, heap), mapped to some unused phys mem
-//   KERNBASE..KERNBASE+1M: mapped to 0..1M
-//   KERNBASE+1M..KERNBASE+end : mapped to 1M..end (mapped without write permission)
-//   KERNBASE+end..KERBASE+PHYSTOP     : mapped to end..PHYSTOP (rw data + free memory)
+//   KERNBASE..KERNBASE+EXTMEM: mapped to 0..EXTMEM  (below extended memory)
+//   KERNBASE+EXTMEM..KERNBASE+end : mapped to EXTMEM..end (mapped without write permission)
+//   KERNBASE+end..KERBASE+maxpa     : mapped to end..maxpa (rw data + free memory)
 //   0xfe000000..0    : mapped direct (devices such as ioapic)
 //
 // The kernel allocates memory for its heap and for user memory
-// between kernend and the end of physical memory (PHYSTOP).
+// between kernend and the end of physical memory (maxpa).
 // The virtual address space of each user program includes the kernel
 // (which is inaccessible in user mode).  The user program sits in
 // the bottom of the address space, and the kernel at the top at KERNBASE.
@@ -118,7 +119,7 @@ static struct kmap {
 } kmap[] = {
   { P2V(0), 0, 1024*1024, PTE_W},  // First 1Mbyte contains BIOS and some IO devices
   { (void *)KERNLINK, V2P(KERNLINK), V2P(data),  0},  // kernel text, rodata
-  { data, V2P(data), PHYSTOP,  PTE_W},  // kernel data, memory
+  { data, V2P(data), 0,  PTE_W},  // kernel data, memory
   { (void*)DEVSPACE, DEVSPACE, 0, PTE_W},  // more devices
 };
 
@@ -129,6 +130,13 @@ setupkvm(char* (*alloc)(void))
   pde_t *pgdir;
   struct kmap *k;
 
+  if (kmap[2].phys_end == 0) {
+    maxpa = detect_memory();
+    kmap[2].phys_end = maxpa;
+    if (p2v(maxpa) > kmap[3].virt)
+      panic("detect_memory: too much memory");
+
+  }
   if((pgdir = (pde_t*)alloc()) == 0)
     return 0;
   memset(pgdir, 0, PGSIZE);