Building dropbear for riscv64 linux

[Jay Aurabind]

Hi,

I'm trying to build dropbear for riscv in a small userland, according
to https://github.com/michaeljclark/busybear-linux/blob/24fc2e81c57f7fa024cc2b911e470fd2104e38d9/scripts/build.sh#L66

I get a the below configure error:

checking build system type... x86_64-unknown-linux-gnu
checking host system type... Invalid configuration
`riscv64-linux-gnu': machine `riscv64' not recognized
configure: error: /bin/bash ./config.sub riscv64-linux-gnu failed

Looking at config.sub, the file does not contain any any entry for
riscv arch. On the contrary, openssh has riscv64 machines entries in
its config.sub:
https://github.com/openssh/openssh-portable/blob/38e83e4f219c752ebb1560633b73f06f0392018b/config.sub#L305

Does dropbear need extra patches? Is there some easy way I can get
dropbear to cross compile ?

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Thanks and Regards,
Aurabindo J