IP28 boot error under 3.16

[Joshua Kinard <kumba@gentoo.org>]

Has anyone tried booting IP28 lately?

I tried a cut of 3.16 from git (~08/05/14) and I get the following crash at
the ARCS console:

Exception: <vector=normal>
Status register: 0x34004882<CU1,CU0,FR,IM7,IM4,IPL=???,KX,MODE=KERNEL>
Cause register: 0x10<CE=0,EXC=RADE>
Exception PC: 0xa800000020654004, Exception RA: 0xa800000020654c9c
Read address error exception, bad address: 0xdfbdd600
Local I/O interrupt register 2: 0x0xc8<EISA,SLOT0,SLOT1>
  Saved user regs in hex (&gpda9000000020f01dc8, & regs 0x9000000020f01fc9):
  arg: dfbe0000 ffffffffa8000000 ffffffffa8000000 40000 20690000 20690000
20690000 9
  tmp: 9 38 0 ffffffff9fc60670
  sve: a8000000204f1330 ffffffff9fc572d0 ffffffff9fc572d3
  t8 206e0000 t9 206e0000 at 34004880 v0 dfbd9800 v1 a800000020654fe0 k1
ffffffffbad11bad
  gp a80000002060c000 fp 740b sp a80000002060fdc0 ra a800000020654c9c

PANIC: Unexpected exception

Going by the Exception PC and the RA, I figured out which line looks to be
causing this:

    (gdb) l *(sgihpc_init+0x78)
    0xa800000020654004 is in sgihpc_init (arch/mips/sgi-ip22/ip22-hpc.c:41).
    36              hpc3c1 = (struct hpc3_regs *)
    37                       ioremap(HPC3_CHIP1_BASE, sizeof(struct hpc3_regs));
    38              /* IOC lives in PBUS PIO channel 6 */
    39              sgioc = (struct sgioc_regs *)hpc3c0->pbus_extregs[6];
    40
--> 41              hpc3c0->pbus_piocfg[6][0] |= HPC3_PIOCFG_DS16;
    42              if (ip22_is_fullhouse()) {
    43                      /* Full House comes with INT2 which lives in
PBUS PIO
    44                       * channel 4 */
    45                      sgint = (struct sgint_regs
*)hpc3c0->pbus_extregs[4];

To me, it looks like a pointer isn't getting converted to 64bit address
space correctly (0xdfbdd600 -> ???).  I haven't played with this IP28
machine for a few years, so I forget what the best approach to fixing this is.

Thoughts?

-- 
Joshua Kinard
Gentoo/MIPS
kumba@gentoo.org
4096R/D25D95E3 2011-03-28

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