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Diffstat (limited to 'results/scraper/launchpad-without-comments/812398')
| -rw-r--r-- | results/scraper/launchpad-without-comments/812398 | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/results/scraper/launchpad-without-comments/812398 b/results/scraper/launchpad-without-comments/812398 new file mode 100644 index 00000000..a39f77a4 --- /dev/null +++ b/results/scraper/launchpad-without-comments/812398 @@ -0,0 +1,11 @@ +powerpc 7450 MMU initialization broken + +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). \ No newline at end of file |