MIPS simulator is broken

["Steve Ellcey " <sellcey@imgtec.com>]

Mike,

Your December 26th change to the mips simulator has broken it, at least
for me.  I am trying to compile and run a program with mips32r2 big-endian
and am using the mti32.ld linker script.

After your commit my attempts to run a 'hello world' program die with:


mips-core: 4 byte read to unmapped address 0xffffffff80020004 at 0xffffffff80020004
program stopped with signal 10 (User defined signal 1).


Any idea what is causing this?

Steve Ellcey
sellcey@imgtec.com



The commit that caused this is:


commit 26f8bf63bf36f9062a5cc1afacf71462a4abe0c8
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Sat Dec 26 11:35:03 2015 -0500

    sim: mips: delete mmu stubs to move to common sim_{read,write}
    
    The only unique thing about mip's sim_{read,write} helpers is the call to
    address_translation on the incoming address.  When we look closer at that
    function though, we see it's just a stub that maps physical to virtual,
    and the cache/return values are hardcoded.  If we delete this function,
    we can then collapse all the callers and drop the custom sim_{read,write}
    logic entirely.
    
    Some day we might want to add MMU support, but when we do, we'll want to
    have the common layers handle things so all targets benefit.