On 4/17/2022 1:12 AM, Martin Trübner wrote:
what would LBEAR do other than a LG Rn,X'110' ?
Martin, X'110' is not the BEAR. The BEAR is a special register that holds the last Breaking Event Address (BEA). X'110' is simply the place where the BEAR is automatically stored when an interrupt occurs.
My assumption is that STBEAR stores the BEAR into into virtual storage so the last BEA can be inspected *without* forcing an interrupt.
Presumably LBEAR is a way of loading the BEAR without requiring a breaking event to do so.
I can envision the usefulness of this for functions that interrupt normal instruction flow (e.g., an interrupt) and wish to restore things back the way they were (including the pre-interrupt BEAR) to maintain transparency.
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