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README.md

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 # RISC-V Hobby OS
 
+[![CI][ci]](https://github.com/rtfb/riscv-hobby-os/actions/workflows/maketest.yml)
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 This is a small hobbyist kernel for RISC-V. It doesn't try to be compatible with
 anything, but happens to go along the old Unix ways. It does preemptive
 multitasking, implements fork+exec system calls, and a bunch of others needed