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).

1 files changed, 2 insertions, 3 deletions

diff --git a/kalloc.c b/kalloc.c
index 9ff3245..35ea6ed 100644
--- a/kalloc.c
+++ b/kalloc.c
@@ -19,7 +19,6 @@ struct {
 } kmem;
 
 extern char end[]; // first address after kernel loaded from ELF file
-extern uint maxpa;        // Maximum physical address
 static char *newend;
 
 // simple page allocator to get off the ground during entry
@@ -51,7 +50,7 @@ kinit(void)
 
   initlock(&kmem.lock, "kmem");
   p = (char*)PGROUNDUP((uint)newend);
-  for(; p + PGSIZE <= (char*)p2v(maxpa); p += PGSIZE)
+  for(; p + PGSIZE <= (char*)p2v(PHYSTOP); p += PGSIZE)
     kfree(p);
 }
 
@@ -65,7 +64,7 @@ kfree(char *v)
 {
   struct run *r;
 
-  if((uint)v % PGSIZE || v < end || v2p(v) >= maxpa)
+  if((uint)v % PGSIZE || v < end || v2p(v) >= PHYSTOP)
     panic("kfree");
 
   // Fill with junk to catch dangling refs.