powerpc 7450 MMU initialization broken
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
QEMU |
Expired
|
Undecided
|
Unassigned |
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_
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).
tags: | added: mmu ppc |
Changed in qemu: | |
status: | Incomplete → Triaged |
Looking through old bug tickets... is this still an issue with the latest version of QEMU? Or could we close this ticket nowadays?