Comment 2 for bug 1449610

Hi,

The unprivileged/privileged extension is optional for armv6-m architecture implementation.[1] Without this extension, it will not support Supervisor Call (SVC). If you want to use SVC, you need to specify the target of -march=armv6s-m.

It will also be better to use -mcpu=cortex-m0 rather than -march=armv6-m, because CPUs like Cortex-m0, Coetex-m0+ are implemented with the unprivileged/privileged extension.

BR,
Tony

[1]You can find more information about such extension in the section A1.2 and A4.9 in the ARMv6m Architecture Reference Manual.