[p3n1cillin]

What

PS5MC (PPSA99420, Kodi 22, catalog release) stops right after its heap: 2048 MiB of direct memory line on Windows:

terminate called after throwing an instance of 'std::runtime_error'
  what():  sysctlbyname_nid_postfix: unsupported name vm.overcommit

All three of its sysctlbyname("vm.overcommit") call sites (guest 0x3A4C351, 0x3A4CFA9, 0x3A4E43E) are mimalloc's unix_detect_overcommit. Each reads the page size through sysconf(47), then vm.overcommit into a zeroed 4-byte int, and sets mimalloc's overcommit flag from (result | value) != 0; mimalloc's start-up messages "secure level: %d" and "mem tracking: %s" follow the first site.

sysctlbyname("vm.overcommit") now reports 0, the default FreeBSD gives its int vm.overcommit. It goes through the existing CopyOut: a null buffer gets the length 4, and a short buffer gets a partial copy and ENOMEM. A write, which FreeBSD takes as a new policy, throws. The console's value is unknown; this is recorded under Unknown function info in docs/dev/debt/libkernel.md.

Tested

• PS5MC PPSA99420 on Windows 11 (MinGW GCC 15.2.0). It loads only with feat(libkernel): carry chflags implementation #4379, feat(libkernel): implement getpriority for the guest process #4374, feat(libkernel): implement sigpending #4383 and feat(libkernel): add clock_settime with FreeBSD argument checks #5183, all on main 3faa9cb40. Before this change it stops as above within 3 s. After, mimalloc starts and Python's start-up is next (feat(libkernel): report _SC_CLK_TCK through sysconf #5185, fix(libkernel): handle FIOCLEX and FIONCLEX in ioctl #5186); with those too, Kodi creates its GUI and runs for the whole 90 s run.
• guest_system_configuration covers the length query, the value, a 2-byte buffer (ENOMEM, the rest untouched, errno otherwise unchanged) and a throwing write. All 125 libkernel tests pass on Windows; Linux was not built locally.
• python tools/check_conventions.py --base origin/main passes. feat(libkernel): report machdep.tsc_freq through sysctlbyname #5078 and feat(libkernel): report hw.realmem through sysctl #5098 add other names in the same part of SystemConfiguration.cpp and the same debt list; whichever merges later needs a trivial rebase.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none to build; PS5MC reaches it with feat(libkernel): carry chflags implementation #4379, feat(libkernel): implement getpriority for the guest process #4374, feat(libkernel): implement sigpending #4383 and feat(libkernel): add clock_settime with FreeBSD argument checks #5183
• Unblocks: PS5MC (PPSA99420)
• AI-assisted: yes

🤖 Generated with Claude Code

[p3n1cillin]

Linux run: Ubuntu in WSL2, GCC 15.2.0, Ninja Release, BUILD_TESTING=ON, full build of a local test head 838d4fd85. That head is main 3faa9cb40 with this PR, my other open libkernel PRs (#5013, #5061, #5078, #5098, #5183–#5187, #5191) and the open PRs the catalog titles need (#4377, #4379, #4374, #4383, #3798, #4467, #4863, #4105). All 123 libkernel and 69 libc tests pass, including guest_system_configuration, guest_getrlimit, guest_kernel_fcntl, guest_freebsd_clocks, guest_kernel_sys and guest_filesystem. Not built alone on Linux; no title run on Linux.

[coltken95]

Tested on Linux x86-64 (Release build), with this PR alone (341fbb2) merged into main 9d0a41d:

• With the PR: guest_system_configuration passes.
• With main's sources and the PR's test: guest_system_configuration aborts.

AI-assisted: yes (Claude Code)

[babyhuey]

A title that stops here on main: PS5MC / kodi-ps5 (PPSA99420, catalog release). Since #4379 (chflags) merged, main bf8dc61 stops it at sysctlbyname_nid_postfix: unsupported name vm.overcommit, just after it maps its heap and opens /dev/crypto (Linux, Ubuntu 24.04, GCC 13, Release, headless). With this PR (341fbb2, clean merge) guest_system_configuration passes. Kodi then starts properly: it loads its settings and initializes its services, and exits on its own at a later step, XBPython: Python initialization failed in _PyImport_InitExternal: external importer setup failed (a bare RuntimeError), then CServiceManager::InitStageTwo: Unable to initialize the python binding modules, XBMC_Run returned -1.

[oneandonlydean]

Rebased onto main to resolve the conflict in docs/dev/debt/libkernel.md after #5098; no other change.