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ARMCC compiling for A7

Note: This was originally posted on 28th March 2013 at http://forums.arm.com

Hi,

I am trying to build my project for the cortex A7. I am currently running an older version of the realview tools. I wanted to know what the difference is between the cpu = 7-a and cpu = cortex-a7 options was?
Will the A7 be able to run code compiled using the 7-a option?

Thanks
Mohit

Mohit Taneja over 12 years ago

Note: This was originally posted on 28th March 2013 at http://forums.arm.com

Thanks!
I take it I wont have access to LPAE either?
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Martin Weidmann over 12 years ago

Note: This was originally posted on 28th March 2013 at http://forums.arm.com

The Cortex-A7 processor implements ARMv7-A. So compiling generically for ARMv7-A will produce compatible code. What the compiler will not do is optimize the code specifically for the Cortex-A7's pipeline.

The other potential issue is extensions. ARMv7-A has a number of optional extensions. The Cortex-A7 implements a couple of them, for example Virtualization. If you build for the base architecture, the tools will fault if you try to use an instruction that was added by an extension. That said, I don't usually find this to be a problem if I'm compiling C code. It tends to only be assembler (e.g. hand written init code) that uses this kind of feature.
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Peter Harris over 12 years ago

Note: This was originally posted on 28th March 2013 at http://forums.arm.com

IIRC LPAE isn't an ISA level extension, so I don't think the compiler output changes.
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