[SPARC64]: Move ramdisk discovery code out to seperate function.

And add some comments explaining all of the quirks involved in
the way the bootloader provides this information.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index f37078d964073561cda5cbd9a71f9228dcadfc0a..21e9267608c74fb5a7faea7a759a0840029cf37e 100644 (file)
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -883,6 +883,37 @@ static void __init trim_pavail(unsigned long *cur_size_p,
        }
 }
 
+static void __init find_ramdisk(unsigned long phys_base)
+{
+#ifdef CONFIG_BLK_DEV_INITRD
+       if (sparc_ramdisk_image || sparc_ramdisk_image64) {
+               unsigned long ramdisk_image;
+
+               /* Older versions of the bootloader only supported a
+                * 32-bit physical address for the ramdisk image
+                * location, stored at sparc_ramdisk_image.  Newer
+                * SILO versions set sparc_ramdisk_image to zero and
+                * provide a full 64-bit physical address at
+                * sparc_ramdisk_image64.
+                */
+               ramdisk_image = sparc_ramdisk_image;
+               if (!ramdisk_image)
+                       ramdisk_image = sparc_ramdisk_image64;
+
+               /* Another bootloader quirk.  The bootloader normalizes
+                * the physical address to KERNBASE, so we have to
+                * factor that back out and add in the lowest valid
+                * physical page address to get the true physical address.
+                */
+               ramdisk_image -= KERNBASE;
+               ramdisk_image += phys_base;
+
+               initrd_start = ramdisk_image;
+               initrd_end = ramdisk_image + sparc_ramdisk_size;
+       }
+#endif
+}
+
 /* About pages_avail, this is the value we will use to calculate
  * the zholes_size[] argument given to free_area_init_node().  The
  * page allocator uses this to calculate nr_kernel_pages,
@@ -912,30 +943,6 @@ static unsigned long __init bootmem_init(unsigned long *pages_avail,
                bytes_avail += pavail[i].reg_size;
        }
 
-       /* Determine the location of the initial ramdisk before trying
-        * to honor the "mem=xxx" command line argument.  We must know
-        * where the kernel image and the ramdisk image are so that we
-        * do not trim those two areas from the physical memory map.
-        */
-
-#ifdef CONFIG_BLK_DEV_INITRD
-       /* Now have to check initial ramdisk, so that bootmap does not overwrite it */
-       if (sparc_ramdisk_image || sparc_ramdisk_image64) {
-               unsigned long ramdisk_image = sparc_ramdisk_image ?
-                       sparc_ramdisk_image : sparc_ramdisk_image64;
-               ramdisk_image -= KERNBASE;
-               initrd_start = ramdisk_image + phys_base;
-               initrd_end = initrd_start + sparc_ramdisk_size;
-               if (initrd_end > end_of_phys_memory) {
-                       printk(KERN_CRIT "initrd extends beyond end of memory "
-                                        "(0x%016lx > 0x%016lx)\ndisabling initrd\n",
-                              initrd_end, end_of_phys_memory);
-                       initrd_start = 0;
-                       initrd_end = 0;
-               }
-       }
-#endif 
-
        if (cmdline_memory_size &&
            bytes_avail > cmdline_memory_size)
                trim_pavail(&bytes_avail,
@@ -1337,6 +1344,8 @@ void __init paging_init(void)
        for (i = 0; i < pavail_ents; i++)
                phys_base = min(phys_base, pavail[i].phys_addr);
 
+       find_ramdisk(phys_base);
+
        set_bit(0, mmu_context_bmap);
 
        shift = kern_base + PAGE_OFFSET - ((unsigned long)KERNBASE);