ARM946. Hardware vector floating-point with software floating-point linkage

Asked by Vyacheslav K. on 2017-12-05

Hi!

I wanna migrate from ARM Compiler to your toolchain for ARM 946 target. I was little bit confused, when saw output of --print-multi-lib.
In ARM Compiler, I use softvfp+vfpv2 for hard vector float and soft linkage. In GNU ARM Embedded Toolchain, I don't see lib for armv5t architecture in --print-multi-lib output. Can I used this toolchain for build my project with described above requirement?

Question information

Language:
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Status:
Solved
For:
GNU ARM Embedded Toolchain Edit question
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Solved by:
Thomas Preud'homme
Solved:
2017-12-06
Last query:
2017-12-06
Last reply:
2017-12-06

Hi Vyacheslav,

Armv5T can be targeted (the default multilib 'thumb' targets Armv4T) but I'm afraid we don't have a multilib for vfpv2 so you'd have to use softfloat. Hope this helps.

Best regards.

Vyacheslav K. (grizzzly) said : #2

Thank you Thomas!

Do I understand correctly that I can use only 'soft' mode (only emulation of float point by using library)? Not 'softfp'.

P.S. So I'll try to build own toolchain for Armv5T with 'softfp' and/or 'hard' based on configures of GNU ARM Embedded Toolchain.

Yes, you should use -mfloat-abi=soft. softfp would still generate VFP instructions and we don't have a multilib for VFPv2.

Best regards,

Thomas

Hi again,

My mistake, I forgot the details of our multilib. We have a multilib for ARMv4T with VFPv2 in hardfloat variant. We don't have one for softfp though. So you can use our toolchain with -march=armv5t -mfloat-abi=hard and it'll work just fine for you.

Best regards.

Vyacheslav K. (grizzzly) said : #5

Thanks Thomas Preud'homme, that solved my question.