SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world.
And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download two short videos (registration required) highlighting:

System Workbench for STM32

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Hex generating

I my case, I wanted SREC output, so this post helped a lot.
I have one thing to add - noted above by Kevin also - the forum software on this site changes the quote characters!
If you are cutting and pasting be aware of that - compare “this” to "this" and note the substitution of curly quotes in the first for the straight quotes in the second which is in “monospace font/code sample” quoting - see help.
This should work:

arm-none-eabi-objcopy -O binary "${BuildArtifactFileBaseName}.elf" "${BuildArtifactFileBaseName}.bin" && arm-none-eabi-objcopy --output-target=srec "${BuildArtifactFileBaseName}.elf" "${BuildArtifactFileBaseName}.srec" && arm-none-eabi-size "${BuildArtifactFileName}"

so you can also do
arm-none-eabi-objcopy --info
to see the supported output formats for your platform.

(edit to acknowledge Kevin and to add output format example)