See the thread starting at
https://sourceware.org/pipermail/gdb/2020-July/048808.html
and in particular the analysis I give in
https://sourceware.org/pipermail/gdb/2020-July/048817.html

The manual states in the section E.1 about the remote protocol that remote
stubs must implement the 's' command. This appears to be false. Further, it
does not mention the '?' command, which does appear to be required.

The attached patch against git master at the time of writing fixes these
two nits.

-- 
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