Add -p flag: force physical memory addressing

4 files changed, 17 insertions, 10 deletions

diff --git a/pk/handlers.c b/pk/handlers.c
index 972a5dc..2c50ae6 100644
--- a/pk/handlers.c
+++ b/pk/handlers.c
@@ -4,10 +4,7 @@
 #include "config.h"
 #include "syscall.h"
 #include "vm.h"
-
-int have_fp = 1; // initialized to 1 because it can't be in the .bss section!
-int have_accelerator = 1;
-  
+ 
 static void handle_accelerator_disabled(trapframe_t* tf)
 {
   if (have_accelerator)
diff --git a/pk/init.c b/pk/init.c
index 84b28f3..6ca3c49 100644
--- a/pk/init.c
+++ b/pk/init.c
@@ -9,6 +9,9 @@
 #include <string.h>
 
 elf_info current;
+int have_vm = 1; // unless -p flag is given
+int have_fp;
+int have_accelerator;
 
 void init_tf(trapframe_t* tf, long pc, long sp, int user64)
 {
@@ -26,10 +29,14 @@ static void handle_option(const char* s)
 {
   switch (s[1])
   {
-    case 's':
+    case 's': // print cycle count upon termination
       current.t0 = rdcycle();
       break;
 
+    case 'p': // physical memory mode
+      have_vm = 0;
+      break;
+
     default:
       panic("unrecognized option: `%c'", s[1]);
       break;
diff --git a/pk/pk.h b/pk/pk.h
index 2be2069..282530c 100644
--- a/pk/pk.h
+++ b/pk/pk.h
@@ -34,7 +34,8 @@ extern "C" {
 #endif
 
 extern int have_fp;
-extern int have_vector;
+extern int have_accelerator;
+extern int have_vm;
 extern uint32_t mem_mb;
 int emulate_fp(trapframe_t*);
 void init_fp(trapframe_t* tf);
diff --git a/pk/vm.c b/pk/vm.c
index d7371c5..6f02930 100644
--- a/pk/vm.c
+++ b/pk/vm.c
@@ -23,7 +23,6 @@ static pte_t* root_page_table;
 static uintptr_t first_free_page;
 static size_t next_free_page;
 static size_t free_pages;
-static int have_vm;
 
 static uintptr_t __page_alloc()
 {
@@ -408,9 +407,12 @@ void vm_init()
 
     __map_kernel_range(0, current.user_min, PROT_READ|PROT_WRITE|PROT_EXEC);
 
-    write_csr(ptbr, root_page_table_paddr);
-    set_csr(status, SR_VM);
-    have_vm = clear_csr(status, SR_VM) & SR_VM;
+    if (have_vm)
+    {
+      write_csr(ptbr, root_page_table_paddr);
+      set_csr(status, SR_VM);
+      have_vm = clear_csr(status, SR_VM) & SR_VM;
+    }
 
     size_t stack_size = RISCV_PGSIZE * stack_pages;
     current.stack_top = MIN(first_free_page, 0x80000000); // for RV32 sanity