[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>

1 files changed, 33 insertions, 24 deletions

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index f37078d9640..21e9267608c 100644
--- 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);