make coverage-html failed with no rule found

[Jiatong Shen]

Hello community,

    I am trying to get qemu uniting test coverage report. I find this https://www.qemu.org/docs/master/devel/testing.html#gcc-gcov-support link might be relevant. but when I execute make  coverage-html. 

it complains

make: *** No rule to make target 'coverage-html'.  Stop

What am I doing wrong? Would be appreciated to receive help. Thank you very much in advance.

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Best Regards,

Jiatong Shen