Re: [Qemu-devel] [PATCH 1/2] decodetree: Initial support for variable-length ISAs

[Peter Maydell]

On Thu, 31 Jan 2019 at 21:10, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Assuming that the ISA clearly describes how to determine
> the length of the instruction, and the ISA has a reasonable
> maximum instruction length, the input to the decoder can be
> right-justified in an appropriate insn word.
>
> This is not 100% convenient, as out-of-line %fields are
> numbered relative to the maximum instruction length, but
> this appears to still be usable.

Prompted by a query on IRC I noticed that this patch from a few
years back added variable-insn-width support to decodetree,
including a new commandline argument --varinsnwidth, but
we don't document how to use it in docs/devel/decodetree.rst.
In fact decodetree.rst doesn't document decodetree.py's
commandline options at all. Could you maybe write up a
docs patch to describe them?

thanks
-- PMM