From 6f2327580fe9a5f5b093814126fe7ffc02345407 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@26-4-190.dynamic.csail.mit.edu>
Date: Wed, 24 Aug 2011 10:24:40 -0400
Subject: [PATCH] Eliminate USERTOP; no use for it.
---
memlayout.h | 1 -
vm.c | 6 +++---
2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/memlayout.h b/memlayout.h
index ad4fda2..c2879b1 100644
--- a/memlayout.h
+++ b/memlayout.h
@@ -6,7 +6,6 @@
// Key addresses for address space layout (see kmap in vm.c for the layout)
#define KERNBASE 0xF0000000 // First kernel virtual address
-#define USERTOP (KERNBASE-PGSIZE) // Highest user virtual address
#define KERNLINK (KERNBASE+EXTMEM) // Address where kernel is linked
#ifndef __ASSEMBLER__
diff --git a/vm.c b/vm.c
index e509a72..59c95ca 100644
--- a/vm.c
+++ b/vm.c
@@ -99,7 +99,7 @@ mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm, char* (*alloc)(vo
// than its memory.
//
// setupkvm() and exec() set up every page table like this:
-// 0..USERTOP : user memory (text, data, stack, heap), mapped to some unused phys mem
+// 0..KERNBASE : 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+PHYSTOP : mapped to end..PHYSTOP (rw data + free memory)
@@ -223,7 +223,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
char *mem;
uint a;
- if(newsz > USERTOP)
+ if(newsz >= KERNBASE)
return 0;
if(newsz < oldsz)
return oldsz;
@@ -279,7 +279,7 @@ freevm(pde_t *pgdir)
if(pgdir == 0)
panic("freevm: no pgdir");
- deallocuvm(pgdir, USERTOP, 0);
+ deallocuvm(pgdir, KERNBASE, 0);
for(i = 0; i < NPDENTRIES; i++){
if(pgdir[i] & PTE_P) {
char * v = p2v(PTE_ADDR(pgdir[i]));
--
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