[Qemu-devel] [Bug 811683] Re: 7400, 7410, 7450 cpus vector have wrong exception prefix at reset

[till]

Google for MPC7450UM.pdf and MPC7410UM.pdf. These two documents cover
the

7441, 7445, 7451, 7455, 7457, 7447, 7448 and the 7410 and 7400 CPUs,
respectively.

For all these, Alex' description applies. However, (and I made a mistake in my 
original post),
the setting affected is

env->hreset_excp_prefix = 0xfff00000UL;

in addition, hreset_vector should be:

env->hreset_vector = 0x00000100UL;

NOTE - I believe the other points raised by Alex (initialize MSR[IP] --
which BTW is called MSR_EP in qemu -- and switching the exception prefix
when MSR[IP] is changed) are already correctly handled, see:

target-ppc/helper.c: cpu_reset()
target-ppc/helper-hreg.h: hreg_store_msr()

Should I post a patch to the mailing-list?

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https://bugs.launchpad.net/bugs/811683

Title:
  7400,7410,7450 cpus vector have wrong exception prefix at reset

Status in QEMU:
  New

Bug description:
  I have a proprietary ROM implementing system calls that are executed
  via the 'SC' instruction.

  I use qemu-0.14.1,

  qemu-system-ppc -M prep -cpu $CPU -bios my_bios -kernel my_kernel

  That works fine on a 604 (CPU=0x00040103) - but does not on an emulated 7400 
(CPU=0x000c0209) or 7450 (CPU=0x80000201). I found that the emulator jumps to 
0x00000c00 instead of 0xfff00c00.
  Probably this is due to a wrong setting in target-ppc/translate_init.c:

  init_excp_604() correctly sets env->hreset_vector=0xfff00000UL;

  but

  init_excp_7400() says env->hreset_vector=0x00000000UL;

  which seems wrong. (the 7400 manual says a hard-reset jumps initializes the
  prefix to 0xfff00000.)

  Likewise, init_excp_7450() (and probably other, related CPUs) are
  wrong.

  Indeed, when I change the value in init_excp_7400() to 0xfff00000UL then
  everything works as expected for me.

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