char* kalloc(void);
void kfree(char*);
void kinit(void);
+uint detect_memory(void);
// kbd.c
void kbdintr(void);
} 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 *
return p;
}
+uint
+detect_memory(void)
+{
+ return 0xE000000;
+}
+
// Initialize free list of physical pages.
void
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);
}
{
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.
// Start additional processor running entry code at addr.
// See Appendix B of MultiProcessor Specification.
void
-
lapicstartap(uchar apicid, uint addr)
{
int i;
microdelay(200);
}
}
+
+
// 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__
#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
#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];
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))
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)
//
// 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.
} 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
};
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);
projects / cs3210-lab0.git / commitdiff