Add -p flag to pk to disable demand paging

pk/mmap.c

@@ -24,7 +24,7 @@ static uintptr_t first_free_page;
 static size_t next_free_page;
 static size_t free_pages;
 
-int have_vm = 1; // unless -p flag is given
+int demand_paging = 1; // unless -p flag is given
 
 static uintptr_t __page_alloc()
 {
@@ -244,7 +244,7 @@ uintptr_t __do_mmap(uintptr_t addr, size_t length, int prot, int flags, file_t*
     *pte = (pte_t)v;
   }
 
-  if (!have_vm || (flags & MAP_POPULATE))
+  if (!demand_paging || (flags & MAP_POPULATE))
     for (uintptr_t a = addr; a < addr + length; a += RISCV_PGSIZE)
       kassert(__handle_page_fault(a, prot) == 0);
 

pk/mmap.h

@@ -19,7 +19,7 @@
 #define MAP_POPULATE 0x8000
 #define MREMAP_FIXED 0x2
 
-extern int have_vm;
+extern int demand_paging;
 uintptr_t pk_vm_init();
 int handle_page_fault(uintptr_t vaddr, int prot);
 void populate_mapping(const void* start, size_t size, int prot);

pk/pk.c

@@ -16,6 +16,10 @@ static void handle_option(const char* s)
       current.cycle0 = 1;
       break;
 
+    case 'p': // disable demand paging
+      demand_paging = 0;
+      break;
+
     default:
       panic("unrecognized option: `%c'", s[1]);
       break;