[Qemu-devel] [Bug 812398] Re: powerpc 7450 MMU initialization broken

[Samuel Bronson]

** Tags added: mmu ppc

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/812398

Title:
  powerpc 7450 MMU initialization broken

Status in QEMU:
  New

Bug description:
  The 7540 family of PPCs' MMU can update TLBs using hardware search
  (like a 604 or 7400) but also using a software algorithm. The
  mechanism used is defined by HID0[STEN].

  By default (CPU reset) HID0 is set to 0x80000000 (BTW; another small bug, 
qemu doesn't set the hardwired MSB), hence
  the software-table lookup feature is *disabled*. However, the default (and 
immutable) 'mmu_model' for this CPU family is POWERC_MMU_SOFT_74XX which choses 
the soft TLB replacement scheme.

  To fix this:

  1) the initial mmu_model for the 7450 family (includes 7441, 7445, 7451, 
7455, 7457, 7447, 7448) should be: POWERPC_MMU_32B
  2) when HID0[STEN] is written then the mmu_model should be changed 
accordingly (I'm not familiar enough with the qemu internal state to judge if 
any cached state would have to be updated).

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/812398/+subscriptions