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RISC-V support has been merged in FreeRTOS. A couple of boards is directly supported.

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Haiku

Haiku has been ported to RISC-V: https://www.haiku-os.org/blog/kallisti5/2021-11-07_booting_our_risc-v_images/

Illumos

Illumos has been ported to the Allwinner D1: https://github.com/n-hys/illumos-gate/wiki/Allwinner-D1-Nezha

Linux

RISC-V Maintainers

• Palmer Dabbelt
• Albert Ou
• Paul Walmsley

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The Linux kernel supports RV64G as well as RV32G.

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Oberon

There is an Oberon port for RISC-V, e.g., for the Bouffalo Lab BL808: http://oberon.wikidot.com/project-oberon-v

OpenBSD

Releases

RISC-V Status

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• https://www.openbsd.org/riscv64.html
• https://www.openbsd.org/papers/Porting_OpenBSD_to_RISCV_FinalReport.pdf

xv6

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Plan 9

Plan 9 ports exist; see also: https://ntnuopen.ntnu.no/ntnu-xmlui/bitstream/handle/11250/2902876/no.ntnu:inspera:74730513:31541262.pdf?sequence=1

Haiku

Haiku has been ported to RISC-V: https://www.haiku-os.org/blog/kallisti5/2021-11-07_booting_our_risc-v_images/

Oberon

There is an Oberon port for RISC-V, e.g., for the Bouffalo Lab BL808: http://oberon.wikidot.com/project-oberon-v

Illumos

xv6

There are multiple RISC-V ports of xv6, including one for Illumos has been ported to the Allwinner D1: https://github.com/n-hysmichaelengel/illumos-gate/wiki/Allwinner-D1-Nezhaxv6-d1