GNU Arm Embedded Toolchain

Compatbility of toolchain with Armv7-A (Cortex-A8)

Asked by Peter

The front of the website sates that the tool-chain supports the Cortex-R7 (ARMv7-R architecture) series processor. However, the very similar Cortex-A8 (ARMv7-A architecture) doesn't seem to be supported.

My understanding is that the only difference between ARMv7-A and ARMv7-R is that the A profile has virtual memory and the R profile has protected memory. This affects the co-processor 15 registers and behaviors, but it doesn't seem like this would impact a no-OS toolchain. Additionally a thread on this forum (link below) seems to indicate that compiling should work for the Cortex-8A.

https://answers.launchpad.net/gcc-arm-embedded/+question/240556

So my questions are:
1.) Why isn't there official support for Cortex A8?
2.) What are the potential incompatibilities when compiling for the Cortex-A8?

Regards
Peter

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Tejas Belagod (belagod-tejas) said : 		#1

Hi Peter,

Besides VMSA, there are subtle ISA differences between the ARMv7-A and ARMv7-R profiles, viz (S/U)DIV.

Technically speaking, this toolchain could work for a bare-metal A-profile target, but it is not this project's (GCC ARM Embedded) mandate to provide support for an A-profile target. Therefore, we don't test or tune this toolchain for A-profile targets extensively - we only run a basic validation for A-profile targets.

The multilibs we configure/build are R and M profiles only, so if you compile an application for an A-profile target, you will be linking in generic ARMv7 ARM/Thumb libraries into your application (eg. you will not link in Cortex-A8-tuned memcpy).

This project is highly focussed on R/M-profile architectures, so we can't promise to support A-profile actively. As the link says, this is something you could get from linaro or build one from upstream sources.

Has this answered your question?

Thanks,
Tejas.

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Peter (peter-mckinnis) said : 		#2

Tejas

Thanks for the very helpful response. Looks like the linaro builds will work well.

Regards
Peter