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Question on the role of MXR with respect to different transformations #84
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Which of the two operations is performed depends entirely on whether the address is virtual or physical and is not affected by MXR or MPRV. I.e., the fact that it is a physical address has no impact on whether pointer masking is applied, just which of the two operations it is. In this case, because MXR=1, no pointer masking will be applied. |
@martinmaas The privileged spec says
which in M-mode accesses are not using virtual memory. The spec here says
This seems to indicate that MXR=1 should not affect whether pointer masking is applied. |
Although MXR has no effect on permission checks, it does have an effect on whether or not pointer masking applies. We agree that these two statements taken together could lead to confusion, and we will thus add the following non-normative statement after the second paragraph quoted above:
(Please note that this is just adding a non-normative clarifying statement and not a change to the spec.) |
Hi,
The
Zjpm
spec mentions two different types of transformations:It also specifies that
MXR
being set disables pointer masking. Can you clarify if that applies to physical address transformation as well?Specifically, I am trying to understand the behavior when:
Mode = M, mstatus.MPRV=0, mstatus.MXR=1 and a load/store from/to physical address is performed. Does a ignore transformation on physical address occur in this case?
Thank you.
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