From 5f069dcf2f9d833a6c4f58ed87269d61c6abb687 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@Frans-Kaashoeks-MacBook-Pro.local>
Date: Tue, 16 Aug 2011 20:23:17 -0400
Subject: Switch back to #define for PHYSTOP. Using the E820 to retrieve the
memory map is too complicated (must be done in 16-bit real-mode, probably
enlarged bootblock beyond 512 bytes, and a #define requires less
explanation).
---
vm.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
(limited to 'vm.c')
diff --git a/vm.c b/vm.c
index 0011188..e509a72 100644
--- a/vm.c
+++ b/vm.c
@@ -8,7 +8,6 @@
#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];
@@ -103,11 +102,11 @@ mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(vo
// 0..USERTOP : user memory (text, data, stack, heap), mapped to some unused phys mem
// 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)
+// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (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 (maxpa).
+// between kernend and the end of physical memory (PHYSTOP).
// 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.
@@ -119,7 +118,7 @@ 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), 0, PTE_W}, // kernel data, memory
+ { data, V2P(data), PHYSTOP, PTE_W}, // kernel data, memory
{ (void*)DEVSPACE, DEVSPACE, 0, PTE_W}, // more devices
};
@@ -130,17 +129,12 @@ 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);
k = kmap;
+ if (p2v(PHYSTOP) > (void *) DEVSPACE)
+ panic("PHYSTOP too high");
for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
if(mappages(pgdir, k->virt, k->phys_end - k->phys_start, (uint)k->phys_start,
k->perm, alloc) < 0)
--
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