Game bring-up: ProsperoCraft (PPSA99874): runs 120 s with #12436, #7532 and #9684

[milescoviello]

Status: on main, it aborts 3 s after start in sysctl (vm.loadavg). With #12436 it gets past that call, and the JVM then stops on a guard-page mprotect of its primordial thread's stack. With #12436, #7532 and #9684 merged together, it runs the full 120 s, and its Instances screen, new-instance form and on-screen keyboard follow pad input.

Setup

• Title: ProsperoCraft (PPSA99874 01.000.117), the catalog's Minecraft Java launcher with a Java 25 runtime
• Linux: Ubuntu 26.04.1 (kernel 7.0), i7-13700K, RTX 4070 Ti, NVIDIA 615.71.09, GCC 15.2, release libs, 120 s with pad input

The stops

1. On main:

   terminate called after throwing an instance of 'std::runtime_error'
     what():  sysctl_nid_postfix: unsupported MIB 2.2
   

   MIB {2, 2} is FreeBSD's vm.loadavg. The runtime's libjvm.so has its own getloadavg, which reads it through sysctl.
2. With fix(libkernel): answer vm.loadavg with the host's load averages #12436: Native memory allocation (mprotect) failed to protect 49152 bytes. Error detail: memory to guard stack pages (stackOverflow.cpp:113). The primordial thread runs on the host process's main stack, which guest mprotect doesn't cover.

Pull requests from this title

• fix(libkernel): answer vm.loadavg with the host's load averages #12436: vm.loadavg answers with the host's load averages.
• fix(linux): enter the guest entry on a main stack at the console's address #7532 (hugodearaujo): the guest entry on a main stack at the console's address.
• fix(libkernel): start thread stacks on a 16 KiB page boundary on Linux #9684 (NevesHenry): 16 KiB-aligned thread stacks.

AI-assisted: yes (Claude Code)