Changeset cae5404 in mainline

Timestamp:

2010-06-26T21:59:52Z (14 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

720db0c

Parents:

decfbe56

Message:

add simple temporary workaround (far from any proper solution) for the infamous ticket #3

File:

• kernel/arch/ia32/src/mm/frame.c (modified) (3 diffs)

kernel/arch/ia32/src/mm/frame.c

@@ -47 +47 @@
 #include <print.h>
 
+#define PHYSMEM_LIMIT  0x7C000000
+
 size_t hardcoded_unmapped_ktext_size = 0;
 size_t hardcoded_unmapped_kdata_size = 0;
@@ -55 +57 @@
 {
         unsigned int i;
-
+        
         for (i = 0; i < e820counter; i++) {
                 uint64_t base = e820table[i].base_address;
@@ -61 +63 @@
                 
 #ifdef __32_BITS__
-                /* Ignore physical memory above 4 GB */
-                if ((base >> 32) != 0)
+                /*
+                 * XXX FIXME:
+                 *
+                 * Ignore zones which start above PHYSMEM_LIMIT
+                 * or clip zones which go beyond PHYSMEM_LIMIT.
+                 *
+                 * The PHYSMEM_LIMIT (2 GB - 64 MB) is a rather
+                 * arbitrary constant which allows to have at
+                 * least 64 MB in the kernel address space to
+                 * map hardware resources.
+                 *
+                 * The kernel uses fixed 1:1 identity mapping
+                 * of the physical memory with 2:2 GB split.
+                 * This is a severe limitation of the current
+                 * kernel memory management.
+                 *
+                 */
+                
+                if (base > PHYSMEM_LIMIT)
                         continue;
                 
-                /* Clip regions above 4 GB */
-                if (((base + size) >> 32) != 0)
-                        size = 0xffffffff - base;
+                if (base + size > PHYSMEM_LIMIT)
+                        size = PHYSMEM_LIMIT - base;
 #endif
-
+                
                 pfn_t pfn;
                 size_t count;