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Hi
I have an inquiry. our company is using Cortex-A9 quad Core. So in ARM website there are many technical reference manuals for the same in different revisions , such as:
r2p0
r2p2
r3p0
r4p0
r4p1
so what should i follow?
or should i follow latest revision?
or my SOC has specific revision corresponding to Cortex -A9 implemented, if its so, how can i found it, if my SOC doc does not refers about it?
Hello anoopstm,
the conclusion would be that you should follow the description of your SOC TRM what revision core had been implemented.
Unless your SOC TRM had referred about it, the MIDR (Main ID Register) would be helpful.
It can be referred by the following instruction.
MRC p15, 0, <Rt>, c0, c0, 0 ; Read MIDR into Rt
In MIDR, the Bits[23:20] show "Major revision number, rX" and Bits[3:0] show "Minor revision number, pY".
However, I am not sure whether MIDR information is always valid because I had not tried it.
Anyway, I think that you need not to bother the differences of revisions.
Please refer to the The Birth & Evolution of Cortex-A9, and What’s Coming Next… and you will find the differences basically come from the performance improvement.
From the functional aspect, I think all revisions would be almost the same.
Best regards,
Yasuhiko Koumoto.
Thank you so much for this knowledge.