Strict SystemRDL Compliance
-Vinayak Sharma
SystemRDL exists so that a register specification means the same thing everywhere: to the architect who writes it, the tools that consume it, and the RTL, verification, and software teams who build on it. That promise holds only when the description is interpreted strictly and consistently. When behavior depends on which flags someone remembered to set, or differs from one project to the next, the specification stops being a single source of truth, and mismatches surfaces late, often during integration or silicon bring-up, when they are most expensive to fix.
The -rdlstrict switch in IDS is designed to prevent that. It enforces stricter compliance during generation so that your SystemRDL input produces clean, predictable RTL. In the latest release, it does more out of the box: several behaviors that previously required separate flags are now enabled by default. The result is less setup, fewer missed options, and more consistent output across projects and teams.
Here’s what changed and why it matters.
Smarter Defaults for Common Register Behaviors
The biggest shift is that -rdlstrict now assumes you want certain things every time, because in practice, you usually do.
Hardware-writable registers are automatically volatile. Any register that hardware can modify now gets auto_volatile property applied without you having to add it yourself. This used to be an easy thing to overlook, especially in larger designs with lots of register — now it just happens correctly by default.
External registers get optimized acknowledgment handling. external_ack=optimized property is applied automatically, so external interface accesses are efficient out of the box rather than something you configure after the fact.
Wide memories get wide external read access. For wide memories specifically, wide_external_access=true:r property is now the default, so read access through the external interface is set up correctly without extra flags.
Software writes take precedence. When both software and hardware can touch the same register or field, rtl_precedence=sw property now governs by default — software wins. This gives you one consistent, predictable rule instead of case-by-case ambiguity.
Two Options You No Longer Have to Specify
Two flags that were previously optional are now switched on automatically whenever -rdlstrict is used:
- -preserve— keeps your design information intact through the generation process, which leads to more consistent output.
- -if— automatically triggers the interface-related generation behavior it controls, without needing to be specified separately.
Together, these mean -rdlstrict alone now does what used to take three or four flags combined.
A More Usable Command Line
Beyond the generation defaults, the day-to-day experience of using the tool has improved too.
-verbose is actually useful now. It prints out the names of the files it generates, so you can see exactly what a run produced at a glance — handy for debugging or just double-checking your output.
Getting help is easier. Both –help and –h now work, so you don’t need to remember an exact flag name to pull up usage info.
Status messages are color-coded. Successes show up in green, warnings in yellow, and errors in red. When you’re scanning through a long generation log, that color coding makes it immediately obvious where to look.
Why This Matters
Standards compliance is more than a checkbox. It is what makes a register specification portable across tools, reusable across projects, and trustworthy for every team that depends on it. The more a flow relies on manual configuration, the more room there is for two teams, or two runs, to interpret the same specification differently.
With this release, -rdlstrict closes much of that gap. Safe, consistent defaults for volatility, precedence, and external access are now built in, so the correct behavior no longer depends on remembering the right combination of flags. Improved verbose output and color-coded logs also make it easier to verify exactly what each run produced.
If your scripts currently specify auto_volatile, external_ack, wide_external_access, -preserve, -if, or rtl_precedence=sw, now is a good time to revisit them. In many cases, -rdlstrict covers these settings on its own, so you can simplify your command line and let the tool enforce consistency for you.
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