target/linux/brcm47xx/patches-2.6.33/170-128MB_ram_bugfix.patch

   1 --- a/arch/mips/bcm47xx/prom.c
   2 +++ b/arch/mips/bcm47xx/prom.c
   3 @@ -126,6 +126,7 @@ static __init void prom_init_cmdline(voi
   4  static __init void prom_init_mem(void)
   5  {
   6         unsigned long mem;
   7 +       unsigned long max;
   8
   9         /* Figure out memory size by finding aliases.
  10          *
  11 @@ -134,21 +135,26 @@ static __init void prom_init_mem(void)
  12          * want to reuse the memory used by CFE (around 4MB). That means cfe_*
  13          * functions stop to work at some point during the boot, we should only
  14          * call them at the beginning of the boot.
  15 +        *
  16 +        * BCM47XX uses 128MB for addressing the ram, if the system contains
  17 +        * less that that amount of ram it remaps the ram more often into the
  18 +        * available space.
  19 +        * Accessing memory after 128MB will cause an exception.
  20 +        * max contains the biggest possible address supported by the platform.
  21 +        * If the method wants to try something above we assume 128MB ram.
  22          */
  23 +       max = ((unsigned long)(prom_init) | ((128 << 20) - 1));
  24         for (mem = (1 << 20); mem < (128 << 20); mem += (1 << 20)) {
  25 +               if (((unsigned long)(prom_init) + mem) > max) {
  26 +                       mem = (128 << 20);
  27 +                       printk("assume 128MB RAM\n");
  28 +                       break;
  29 +               }
  30                 if (*(unsigned long *)((unsigned long)(prom_init) + mem) ==
  31                     *(unsigned long *)(prom_init))
  32                         break;
  33         }
  34
  35 -       /* Ignoring the last page when ddr size is 128M. Cached
  36 -        * accesses to last page is causing the processor to prefetch
  37 -        * using address above 128M stepping out of the ddr address
  38 -        * space.
  39 -        */
  40 -       if (mem == 0x8000000)
  41 -               mem -= 0x1000;
  42 -
  43         add_memory_region(0, mem, BOOT_MEM_RAM);
  44  }
  45