Flags passed via a settings file (`.hotspotrc`, or `-XX:Flags=my-file`) do not have the `-XX:` prefix like they would have if passed as command-line args. `JVM_GetVmArguments` then prints these flags also without the prefix, along with command-line flags that _are_ prefixed. However, users of `JVM_GetVmArguments` expect the arguments to be in a format that they can pass as command-line args, for example [in CDS static_dump](https://github.com/openjdk/jdk/blob/63f00fff921ed4ac0f595a0a013d399700433a2c...) - CDS static_dump currently *does not work* if the main VM uses flags from a settings file. So, always add the `-XX:` prefix to flags from settings files in `JVM_GetVmArguments`. Updated existing test to cover this behaviour. I looked for existing users of `JVM_GetVmArguments` and they either seem like they'll benefit from this change (CDS, JMH via `RuntimeMXBean.getInputArguments()`) or they won't care. **Testing** * Updated the existing InputArgument test with a case that verifies the new behaviour. * Confirmed that CDS static_dump and JMH now work on a VM with flags from a file. ------------- Commit messages: - 8378110: Add -XX: prefix to settings-file flags in RuntimeMXBean.getInputArguments() Changes: https://git.openjdk.org/jdk/pull/29793/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29793&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8378110 Stats: 50 lines in 2 files changed: 37 ins; 5 del; 8 mod Patch: https://git.openjdk.org/jdk/pull/29793.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/29793/head:pull/29793 PR: https://git.openjdk.org/jdk/pull/29793