MIPS: init: Prevent adding memory before PHYS_OFFSET

On some SGI machines (IP28 and IP30) a small region of memory is mirrored
to pyhsical address 0 for exception vectors while rest of the memory
is reachable at a higher physical address. ARC PROM marks this
region as reserved, but with commit a94e4f24ec83 ("MIPS: init: Drop
boot_mem_map") this chunk is used, when searching for start of ram,
which breaks at least IP28 and IP30 machines. To fix this
add_region_memory() checks for start address < PHYS_OFFSET and ignores
these chunks.

Fixes: a94e4f24ec83 ("MIPS: init: Drop boot_mem_map")
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index f5c6b4c6de2474df602ef1f94e8db8194bb6adbb..5eec13b8d222d3940dba7bbf022f52dbfc43fb5b 100644 (file)
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -108,6 +108,9 @@ void __init add_memory_region(phys_addr_t start, phys_addr_t size, long type)
                return;
        }
 
+       if (start < PHYS_OFFSET)
+               return;
+
        memblock_add(start, size);
        /* Reserve any memory except the ordinary RAM ranges. */
        switch (type) {