Imbus/xv6-riscv-kernel
1
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Initial version of single-cpu xv6 with page tables

Browse source
This commit is contained in:
Frans Kaashoek 2010-07-02 14:51:53 -04:00
parent b7a517f227
commit 40889627ba
22 changed files with 307 additions and 152 deletions
Download patch file Download diff file Expand all files Collapse all files

36
kalloc.c
View file

@ -8,6 +8,7 @@
#include "types.h"
#include "defs.h"
#include "param.h"
#include "mmu.h"
#include "spinlock.h"
struct run {
@ -20,21 +21,28 @@ struct {
struct run *freelist;
} kmem;
int nfreemem;
static void
printfreelist(void)
{
struct run *r, **rp;
cprintf("freelist:\n");
for(rp=&kmem.freelist; (r=*rp) != 0; rp=&r->next){
cprintf("0x%x %d=0x%x\n", r, r->len, r->len);
}
}
// Initialize free list of physical pages.
// This code cheats by just considering one megabyte of
// pages after end. Real systems would determine the
// amount of memory available in the system and use it all.
void
kinit(void)
kinit(char *p, uint len)
{
extern char end[];
uint len;
char *p;
initlock(&kmem.lock, "kmem");
p = (char*)(((uint)end + PAGE) & ~(PAGE-1));
len = 256*PAGE; // assume computer has 256 pages of RAM, 1 MB
cprintf("mem = %d\n", len);
cprintf("end 0x%x free = %d(0x%x)\n", p, len);
nfreemem = 0;
kfree(p, len);
}
@ -47,19 +55,23 @@ kfree(char *v, int len)
{
struct run *r, *rend, **rp, *p, *pend;
if(len <= 0 || len % PAGE)
if(len <= 0 || len % PGSIZE)
panic("kfree");
// Fill with junk to catch dangling refs.
memset(v, 1, len);
acquire(&kmem.lock);
nfreemem += len;
p = (struct run*)v;
pend = (struct run*)(v + len);
for(rp=&kmem.freelist; (r=*rp) != 0 && r <= pend; rp=&r->next){
rend = (struct run*)((char*)r + r->len);
if(r <= p && p < rend)
if(r <= p && p < rend) {
cprintf("freeing a free page: r = 0x%x p = 0x%x rend = 0x%x\n",
r, p, rend);
panic("freeing free page");
}
if(rend == p){ // r before p: expand r to include p
r->len += len;
if(r->next && r->next == pend){ // r now next to r->next?
@ -93,7 +105,7 @@ kalloc(int n)
char *p;
struct run *r, **rp;
if(n % PAGE || n <= 0)
if(n % PGSIZE || n <= 0)
panic("kalloc");
acquire(&kmem.lock);
@ -103,6 +115,7 @@ kalloc(int n)
p = (char*)r + r->len;
if(r->len == 0)
*rp = r->next;
nfreemem -= n;
release(&kmem.lock);
return p;
}
@ -112,3 +125,4 @@ kalloc(int n)
cprintf("kalloc: out of memory\n");
return 0;
}