swtch saves callee-saved registers

swtch idles on per-CPU stack, not on calling process's stack
fix pipe bugs
usertest.c tests pipes, fork, exit, close

1 files changed, 5 insertions, 0 deletions

diff --git a/kalloc.c b/kalloc.c
index 5ea38fd..1944508 100644
--- a/kalloc.c
+++ b/kalloc.c
@@ -45,10 +45,15 @@ kfree(char *cp, int len)
   struct run **rr;
   struct run *p = (struct run *) cp;
   struct run *pend = (struct run *) (cp + len);
+  int i;
 
   if(len % PAGE)
     panic("kfree");
 
+  // XXX fill with junk to help debug
+  for(i = 0; i < len; i++)
+    cp[i] = 1;
+
   rr = &freelist;
   while(*rr){
     struct run *rend = (struct run *) ((char *)(*rr) + (*rr)->len);