RFR: 8374744: Enable dumping of APX EGPRs (R16–R31) in JVM fatal error logs

[David Holmes]

On Fri, 30 Jan 2026 00:47:29 GMT, David Holmes <dholmes at openjdk.org> wrote:

> > > Why is this only implemented for Linux?
> > 
> > 
> > Hello David (@dholmes-ora), this change is only implemented for Linux as APX support is available from kernel >= 6.16. For Windows, the status of APX support is not known.
> > Thanks, Vamsi
> 
> None of the code predicated on `UseAPX` is Linux-only but is all OS-agnostic as far as I can see. These changes seem applicable to all x86 platforms: Linux, Windows, macOS. Unfortunately `os::print_register_info` is duplicated across all three OS (with one key difference for each OS - how to read a register from the context).

Of course that is why this is OS-specific - the relevant details need to be exposed by the OS eg. via the `uc_mcontext` on Linux. So in general this could apply to all platforms, but we need the OS-specific way to get the data. Sorry for my misunderstanding.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/29098#issuecomment-3821215854