fix(libkernel): follow the thread priority ranges and POSIX attribute errors measured on a PS5

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/libs/prx/libkernel/Pthread/Posix/Attr.cpp

@@ -1,7 +1,5 @@
 #include <cstdint>
 #include <cstddef>
-#include <stdexcept>
-#include <string>
 #include "SceTypes.hpp"
 #include "prx/libc/include/General.hpp"
 #include "../include/Pthread.hpp"
@@ -58,8 +56,7 @@ int APS5_VABI pthread_attr_getguardsize_nid_postfix(const PthreadAttr* attr, siz
 }
 
 int APS5_VABI pthread_attr_getinheritsched_nid_postfix(const PthreadAttr* attr, int* inherit_sched) {
-    if (!Valid(attr)) return PosixThread::GUEST_EINVAL;
-    if (!inherit_sched) throw std::runtime_error(std::string(__func__) + ": null output");
+    if (!Valid(attr) || !inherit_sched) return PosixThread::GUEST_EINVAL;
     *inherit_sched = (*attr)->_inheritsched;
     return 0;
 }

core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp

@@ -145,7 +145,7 @@ int APS5_VABI pthread_mutexattr_getprotocol_nid_postfix(const PthreadMutexattr*
 
 int APS5_VABI pthread_mutexattr_setprioceiling_nid_postfix(PthreadMutexattr* attr, int prioceiling) {
     if (!attr || !*attr) return PosixThread::GUEST_EINVAL;
-    if ((*attr)->protocol != POSIX_PRIO_PROTECT) return POSIX_EINVAL;
+    if ((*attr)->protocol != POSIX_PRIO_PROTECT || prioceiling < 256 || prioceiling > 767) return POSIX_EINVAL;
     (*attr)->ceiling = prioceiling;
     return 0;
 }

core/libs/prx/libkernel/Pthread/Posix/Thread.cpp

@@ -202,6 +202,10 @@ int APS5_VABI pthread_getschedparam_nid_postfix(Pthread thread, int* policy, Ker
 }
 
 int APS5_VABI pthread_getprio_nid_postfix(Pthread thread) {
+    if (!thread) {
+        *__error_nid_postfix() = PosixThread::GUEST_EINVAL;
+        return -1;
+    }
     const auto lock = LockLiveGuestThread(thread);
     if (!lock.owns_lock()) {
         *__error_nid_postfix() = PosixThread::GUEST_ESRCH;

core/libs/prx/libkernel/Pthread/src/Thread.cpp

@@ -1167,7 +1167,10 @@ void APS5_VABI scePthreadTestcancel() {
 }
 
 int APS5_VABI scePthreadSetprio(Pthread thread, int prio) {
-    if (!thread) return SCE_KERNEL_ERROR_EINVAL;
+    const auto level = static_cast<std::uint32_t>(prio) & 0xffffu;
+    if (!thread || !((level >= 256 && level <= 767) || (level >= 896 && level <= 959))) return SCE_KERNEL_ERROR_EINVAL;
+    const auto live = LockLiveGuestThread(thread);
+    if (!live) return SCE_KERNEL_ERROR_ESRCH;
     thread->priority.store(prio, std::memory_order_relaxed);
     return SCE_OK;
 }

core/libs/tests/GuestPthreadAttr.cpp

@@ -204,13 +204,7 @@ static void CheckSchedulingAttributes() {
 
     Require(pthread_attr_getscope_nid_postfix(&attr, nullptr) == GUEST_EINVAL);
 
-    bool threw = false;
-    try {
-        pthread_attr_getinheritsched_nid_postfix(&attr, nullptr);
-    } catch (const std::exception&) {
-        threw = true;
-    }
-    Require(threw);
+    Require(pthread_attr_getinheritsched_nid_postfix(&attr, nullptr) == GUEST_EINVAL);
 
     Require(scePthreadAttrDestroy(&attr) == SCE_OK);
     Require(pthread_attr_getinheritsched_nid_postfix(&attr, &inherit) == GUEST_EINVAL);
@@ -366,6 +360,11 @@ int main() {
     Require(reported.stackSize == STACK_SIZE);
     Require(reported.detachState == DETACH_JOINABLE);
 
+    for (const int rejected : {-1, 0, 255, 768, 895, 960, 1023, 131840}) Require(scePthreadSetprio(thread, rejected) == SCE_KERNEL_ERROR_EINVAL);
+    for (const int accepted : {256, 900, 959, 65792, -65280}) {
+        Require(scePthreadSetprio(thread, accepted) == SCE_OK);
+        Require(Query(thread).priority == accepted);
+    }
     Require(scePthreadSetprio(thread, UPDATED_PRIORITY) == SCE_OK);
     Require(scePthreadSetaffinity(thread, UPDATED_AFFINITY) == SCE_OK);
     reported = Query(thread);

core/libs/tests/GuestPthreadMutexattr.cpp

@@ -144,6 +144,9 @@ int main() {
     Require(pthread_mutexattr_setprotocol_nid_postfix(&attr, PRIO_PROTECT) == 0);
     Require(pthread_mutexattr_getprotocol_nid_postfix(&attr, &protocol) == 0 && protocol == PRIO_PROTECT);
     Require(pthread_mutexattr_getprioceiling_nid_postfix(&attr, &ceiling) == 0 && ceiling == sched_get_priority_max_nid_postfix(SCHED_RR));
+    for (const int outside : {0, 255, 768, 1000}) Require(pthread_mutexattr_setprioceiling_nid_postfix(&attr, outside) == GUEST_EINVAL);
+    Require(pthread_mutexattr_setprioceiling_nid_postfix(&attr, 256) == 0);
+    Require(pthread_mutexattr_getprioceiling_nid_postfix(&attr, &ceiling) == 0 && ceiling == 256);
     Require(pthread_mutexattr_setprioceiling_nid_postfix(&attr, 300) == 0);
     Require(pthread_mutexattr_getprioceiling_nid_postfix(&attr, &ceiling) == 0 && ceiling == 300);
     PthreadMutex mutex = nullptr;

core/libs/tests/GuestPthreadSchedparam.cpp

@@ -200,7 +200,7 @@ static void* APS5_VABI Spawn(void*) {
 
 int main() {
     *__error_nid_postfix() = 1234;
-    Require(pthread_getprio_nid_postfix(nullptr) == -1 && *__error_nid_postfix() == GUEST_ESRCH);
+    Require(pthread_getprio_nid_postfix(nullptr) == -1 && *__error_nid_postfix() == GUEST_EINVAL);
     Require(pthread_getprio_nid_postfix(reinterpret_cast<Pthread>(std::uintptr_t{1})) == -1 && *__error_nid_postfix() == GUEST_ESRCH);
     Pthread thread = nullptr;
     Require(scePthreadCreate(&thread, nullptr, Run, nullptr, "schedparam") == SCE_OK);

docs/dev/debt/libkernel.md

@@ -4,7 +4,7 @@
 
 - [sceKernelGetSocPowerConsumption](../../../core/libs/prx/libkernel/System/src/ThermalSensors.cpp) (libkernel) - returns `EINVAL` and writes nothing, as `sceKernelGetSocSensorTemperature` does when the host has no sensor: the host's package power is not read (Linux RAPL `energy_uj` is readable by root only, and Windows has no general source). The prototype is not documented. PS5LM Plus (PPSA99581) passes a zeroed 128-byte buffer and, on success, reads its first 32-bit word as milliwatts, accepting 1000 to 350000; on failure it shows 0 W
 - [scePthreadMutexattrSetprotocol](../../../core/libs/prx/libkernel/Pthread/src/Mutex.cpp) (libkernel) - accepts 0 to 2 as a PS5 (firmware 13.60) does and returns `EINVAL` otherwise, but the protocol is not stored or applied: priority inheritance and protection are not modelled. On the console a null or uninitialized mutex attribute returns `EINVAL` from the SCE attribute calls, `scePthreadMutexInit` takes an uninitialized attribute as the default one, and a destroyed mutex returns `EINVAL` from `scePthreadMutexDestroy`; a null mutex pointer crashed the payload and still throws
-- [pthread_mutexattr_setprotocol, pthread_mutexattr_getprotocol, pthread_mutexattr_setprioceiling, pthread_mutexattr_getprioceiling](../../../core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp) (libkernel) - the protocol and the priority ceiling are stored and reported as in [FreeBSD 11 libthr](https://github.com/freebsd/freebsd-src/blob/releng/11.0/lib/libthr/thread/thr_mutexattr.c#L192-L245) (the ceiling is set or read only under `PTHREAD_PRIO_PROTECT`, and setting a protocol resets it to the highest `SCHED_RR` priority). A null, uninitialized or destroyed attribute returns `EINVAL` before the other arguments are checked; this error behavior is unverified on the console. Mutexes do not apply the protocol or ceiling: a priority-inherit or priority-protect mutex locks like a normal one and does not change its owner's priority
+- [pthread_mutexattr_setprotocol, pthread_mutexattr_getprotocol, pthread_mutexattr_setprioceiling, pthread_mutexattr_getprioceiling](../../../core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp) (libkernel) - the protocol and the priority ceiling are stored and reported as in [FreeBSD 11 libthr](https://github.com/freebsd/freebsd-src/blob/releng/11.0/lib/libthr/thread/thr_mutexattr.c#L192-L245) (the ceiling is set or read only under `PTHREAD_PRIO_PROTECT`, and setting a protocol resets it to the highest `SCHED_RR` priority). A payload process on a PS5 (firmware 13.60) accepts protocols 0 to 2, starts the ceiling at 767 when protocol 2 is set, accepts ceilings 256 to 767 and returns `EINVAL` for other protocols and ceilings and for a null, uninitialized or destroyed attribute; a null output of `pthread_mutexattr_getprotocol` crashed it. Mutexes do not apply the protocol or ceiling: a priority-inherit or priority-protect mutex locks like a normal one and does not change its owner's priority
 - [sceCoredumpSetUserDataType](../../../core/libs/prx/libkernel/System/src/Coredump.cpp) (libkernel, NID `Uxqkdta7wEg`) - `(int type)` follows the PS5 12.00 `libkernel.sprx` at 0x138B0: the sign-extended `type` goes to syscall 601 (command 29, third argument 0), and the raw result comes back with no SCE code mapping, so a kernel error is -1 with `errno` set. Which types the kernel accepts is not measured. No dump is produced here, so every type returns 0. Palworld (PPSA23126, #2598) and Hello Neighbor (PPSA35154, discussion #6991) import it; #4144 left it throwing because no signature was known
 - [sceKernelGetMainSocId and sceKernelGetCpumode](../../../core/libs/prx/libkernel/System/src/Process.cpp) (libkernel) both return 0, and [sceKernelGetCpuFrequency](../../../core/libs/prx/libkernel/Time/Time.cpp) returns the host TSC frequency measured for `sceKernelGetTscFrequency`, not the console CPU clock. The PS5's SoC id and CPU mode are unknown; shadPS4's PS4 values are [0x710f10/0x740f30 and 0, 2 or 5 from the param.sfo CPU-mode flags](https://github.com/shadps4-emu/shadPS4/blob/e0a466753a1a/src/core/libraries/kernel/process.cpp). PPSA99203 only logs them (`[console] main SoC id: result=%#x out=%#x`, `CPU: %llu Hz, cpumode %d`), passing a pointer that `sceKernelGetMainSocId` leaves untouched
 - [sceKernelEnableDmemAliasing](../../../core/libs/prx/libkernel/DirectMemory/Export.cpp) (libkernel) returns 0 and changes nothing: direct memory can always be mapped more than once here, as `DoMapDirect` in [DirectMemory.cpp](../../../core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp) only checks that the physical pages are allocated, so there is no aliasing to turn on. [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/e0a466753a1aacbc8db8253be685bf7ab4d9daae/src/core/libraries/kernel/memory.cpp#L39-L43) (PS4) sets a flag there that lifts the `EBUSY` its [`sceKernelMapDirectMemory2`](https://github.com/shadps4-emu/shadPS4/blob/e0a466753a1aacbc8db8253be685bf7ab4d9daae/src/core/libraries/kernel/memory.cpp#L299-L301), and [`sceKernelMapDirectMemory` for SDK 2.50 and later](https://github.com/shadps4-emu/shadPS4/blob/e0a466753a1aacbc8db8253be685bf7ab4d9daae/src/core/libraries/kernel/memory.cpp#L237-L242), return for direct memory that is [already mapped](https://github.com/shadps4-emu/shadPS4/blob/e0a466753a1aacbc8db8253be685bf7ab4d9daae/src/core/memory.cpp#L548-L553); that check is not applied here. The no-argument `int` signature follows shadPS4 and ProsperoEden (PPSA99008), which calls it before mapping the same direct memory again. Whether the PS5 refuses such a mapping without the call is unverified
@@ -67,7 +67,7 @@
 - [sceKernelAioSubmitReadCommandsMultiple / sceKernelAioSubmitWriteCommandsMultiple / sceKernelAioWaitRequests / sceKernelAioPollRequests / sceKernelAioCancelRequest / sceKernelAioCancelRequests / sceKernelAioDeleteRequests](../../../core/libs/prx/libkernel/Aio/src/Aio.cpp) (libkernel) - behaviour from shadPS4 (one id per request for the Multiple submits, cancel turns any request aborted and id 0 reports processing, wait mode 2 returns once one request completed, poll copies every state without waiting); the 128 requests or ids per batch limit is from SharpProspero, with an unknown error, so larger batches throw; wait modes other than 1 (and) and 2 (or) throw; null pointers, negative counts and invalid ids return the codes the single-request siblings use, checked before any state is written
 - [scePthreadAttr setters and getters](../../../core/libs/prx/libkernel/Pthread/src/Attr.cpp) (libkernel) - measured on a PS5 (firmware 13.60): a null or uninitialized attribute returns `EINVAL`, as does a null output of the stack size, detach state and scheduling parameter getters; a policy other than 1 and 3, an inheritance other than 0 and 4, or a priority outside 256 to 767 (or a null parameter) returns `ENOTSUP` (`0x8002002D`); a detach state other than 0 and 1 and a stack size below 16384 return `EINVAL`; any affinity mask is accepted. A null attribute pointer to `scePthreadAttrInit` and a null output of `scePthreadAttrGetaffinity` crashed the payload, so they still throw. A new attribute holds a 64 KiB stack size on the console and 1 MiB here, which the host code that runs on guest threads needs. `scePthreadAttrGetschedpolicy` and `scePthreadAttrGetinheritsched` were not measured and follow [FreeBSD 11.4 libthr](https://github.com/freebsd/freebsd-src/blob/releng/11.4/lib/libthr/thread/thr_attr.c#L216-L262); a null output of `scePthreadAttrGetinheritsched` throws, since libthr writes through it unchecked
 - [scePthreadAttrGet](../../../core/libs/prx/libkernel/Pthread/src/Attr.cpp) and [pthread_attr_get_np](../../../core/libs/prx/libkernel/Pthread/Posix/Attr.cpp) (libkernel) - the returned scheduling policy is unmeasured on a console. Both report the recorded guest policy, following [FreeBSD 11.4 libthr](https://github.com/freebsd/freebsd-src/blob/releng/11.4/lib/libthr/thread/thr_attr.c#L134-L164)
-- [pthread_getprio](../../../core/libs/prx/libkernel/Pthread/Posix/Thread.cpp) (libkernel) is unmeasured on the console. NID `aO+WS2xWuo4` is named in the firmware 3.20 [export inventory](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libkernel.c). Its return and errno contract follows FreeBSD 11 [thr_getprio.c](https://github.com/freebsd/freebsd-src/blob/671fb7df97631020c42ce55527dc49fffe0656b7/lib/libthr/thread/thr_getprio.c): return the recorded guest priority, or -1 with `ESRCH` for an unknown or finished thread. The live-thread registry lock protects the read from a concurrent join. This reports guest scheduler state, not the host scheduling priority.
+- [pthread_getprio, scePthreadSetprio and pthread_setprio](../../../core/libs/prx/libkernel/Pthread/Posix/Thread.cpp) (libkernel) - measured in a payload process on a PS5 (firmware 13.60): `pthread_getprio` returns the priority, -1 with `ESRCH` for a joined thread and -1 with `EINVAL` for a null one; the setters accept a priority whose low 16 bits are 256 to 767 or 896 to 959 (so 65792 and -65280 too, stored as given) and return `EINVAL` otherwise, and `ESRCH` for a thread that has ended. The guest priority is recorded and reported, not applied to the host thread
 - [sceKernelGetAvailableCpumask](../../../core/libs/prx/libkernel/Pthread/src/Thread.cpp) (libkernel) - returns the default thread affinity, 0x1FFF (CPUs 0 to 12), as KytyPS5 does. Titles pin threads within it (PPSA02664 passes 0x1FFB, Hades II PPSA36082 0x3 and 0x3F); whether CPU 13 is available to a title is not confirmed
 - [sceKernelGetCurrentCpu](../../../core/libs/prx/libkernel/System/src/Process.cpp) (libkernel) - guest affinities are not applied to host threads, so the host CPU index is mapped into the calling thread's affinity clipped to `sceKernelGetAvailableCpumask` (the available mask when they do not overlap): host CPU n reports the (n modulo the CPU count)-th CPU of that mask, so a thread pinned to one CPU reports that CPU, as a FreeBSD `cpuset` guarantees on the console. Which CPU the console reports for a thread allowed on several is not known; shadPS4 returns 0
 - [pthread_attr_setsolosched_np](../../../core/libs/prx/libkernel/Pthread/Posix/Attr.cpp) (libkernel) takes `(attr, int)` and stores the value through `scePthreadAttrSetsolosched`, returning `EINVAL` (22) for a null or uninitialized attribute like the other POSIX attribute setters. Only the name is public (aerolib `2+pVfgiEd7A`); the signature and behaviour follow the SCE twin, which [KytyPS5](https://github.com/KytyPS5/KytyPS5/blob/947627d10d4ef4b68ba3c0189aab6c368e70a8d2/src/kernel/pthread.cpp#L2188-L2199) and [sharpemu](https://github.com/sharpemu/sharpemu/blob/a2983692930564815a77f81e74c151268f5b935f/src/SharpEmu.Libs/Kernel/KernelPthreadExtendedCompatExports.cs#L891-L913) store as an `int` without a range check, and [PS5PCEM](https://github.com/iStark/PS5PCEM/blob/71de7681f06c5db59a1120a3bb554c86780c3f5f/src/hle/libs/kernel_threading.zig#L1396-L1398) implements this alias over it. On a PS5 (firmware 13.60) only 0 and 16 are accepted; every other value returns `ENOTSUP` (45, `0x8002002D` from the SCE call) and keeps the stored one, and the SCE calls return `EINVAL` for a null or uninitialized attribute. PPSA15878 passes 16. Threads created from the attribute are not scheduled differently; what solo scheduling does on the console is unknown. Returnal (PPSA01285 v03.000.005) stopped on it with `what(): pthread_attr_setsolosched_np_nid_postfix not implemented` (#2872, #1155); LEGO Horizon Adventures (PPSA14632, #734) and Palworld (PPSA23126, #2598) import it
@@ -141,7 +141,7 @@
 - [ftruncate, truncate, sceKernelFtruncate](../../../core/libs/prx/libkernel/File/src/Stdio.cpp) (libkernel) extend a file on Windows with `SetFileInformationByHandle` (`FileEndOfFileInfo`), which reserves the clusters but writes no zero bytes, and report `EFBIG` for a length the volume cannot hold (`ERROR_INVALID_PARAMETER` on a disk file; seen with a length of `INT64_MAX`, the size from which NTFS refuses it was not measured) and `ENOSPC` when the free space is smaller. FreeBSD 11.4 makes the extension a hole on a file system that has them ([`ffs_truncate`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/ufs/ffs/ffs_inode.c) writes only the last block), so a length above the free space succeeds there. A write behind the end of the file still makes NTFS write zero bytes over the gap, as the file is not sparse. None of this was measured on a console.
 - [readv, writev, preadv, pwritev and their sceKernel forms](../../../core/libs/prx/libkernel/File/src/Stdio.cpp) (libkernel) - unreadable iovec-table errors follow FreeBSD 11.4's [`copyinuio`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/kern/subr_uio.c#L401-L434), not console measurements. The table is copied before inspecting its entries; payload-buffer validation is unchanged. A Linux `process_vm_readv` failure other than `EFAULT` throws, including when the host denies that API.
 - [/dev/random and /dev/urandom](../../../core/libs/prx/libkernel/File/src/RandomDevice.cpp) (libkernel) opened for reading return a descriptor backed by the host null device whose reads are filled with host OS entropy (`getentropy`, `rand_s` on Windows); both paths behave the same, never block, and positioned reads ignore the offset (FreeBSD `random(4)`). Only the exact paths are recognised, `fstat`, `lseek` and `mmap` see the null device, and opening them for writing throws
-- [pthread_attr_getinheritsched, pthread_attr_setinheritsched, pthread_attr_getscope, pthread_attr_setscope, pthread_attr_getstackaddr](../../../core/libs/prx/libkernel/Pthread/Posix/Attr.cpp) (libkernel) follow FreeBSD 11 libthr ([thr_attr.c](https://github.com/freebsd/freebsd-src/blob/5ed7eb0d97ba4436218e810f61bd059acba984c2/lib/libthr/thread/thr_attr.c), [thr_create.c](https://github.com/freebsd/freebsd-src/blob/5ed7eb0d97ba4436218e810f61bd059acba984c2/lib/libthr/thread/thr_create.c)), not measured on the console: the scope defaults to `PTHREAD_SCOPE_SYSTEM` (2), only it and `PTHREAD_SCOPE_PROCESS` (0) are accepted and other values return `EINVAL`, and an inherit value other than `PTHREAD_INHERIT_SCHED` (4) or `PTHREAD_EXPLICIT_SCHED` (0) returns `ENOTSUP`. `pthread_attr_getstackaddr` returns the configured stack address pointer (null by default). A null output of `pthread_attr_getinheritsched` throws, since libthr writes through it unchecked. A thread keeps the scope it was created with, taken from the creating thread under `PTHREAD_INHERIT_SCHED`, and `pthread_attr_get_np` and `scePthreadAttrGet` report it, but every guest thread is a host thread at system scope, so process scope changes nothing
+- [pthread_attr_getinheritsched, pthread_attr_setinheritsched, pthread_attr_getscope, pthread_attr_setscope, pthread_attr_getstackaddr](../../../core/libs/prx/libkernel/Pthread/Posix/Attr.cpp) (libkernel) follow FreeBSD 11 libthr ([thr_attr.c](https://github.com/freebsd/freebsd-src/blob/5ed7eb0d97ba4436218e810f61bd059acba984c2/lib/libthr/thread/thr_attr.c), [thr_create.c](https://github.com/freebsd/freebsd-src/blob/5ed7eb0d97ba4436218e810f61bd059acba984c2/lib/libthr/thread/thr_create.c)), measured in a payload process on a PS5 (firmware 13.60): the scope defaults to `PTHREAD_SCOPE_SYSTEM` (2), only it and `PTHREAD_SCOPE_PROCESS` (0) are accepted and other values return `EINVAL`, and an inherit value other than `PTHREAD_INHERIT_SCHED` (4) or `PTHREAD_EXPLICIT_SCHED` (0) returns `ENOTSUP`. `pthread_attr_getstackaddr` returns the configured stack address pointer (null by default). A null output of these getters, a null or uninitialized attribute and a destroyed one return `EINVAL`, as measured. A thread keeps the scope it was created with, taken from the creating thread under `PTHREAD_INHERIT_SCHED`, and `pthread_attr_get_np` and `scePthreadAttrGet` report it, but every guest thread is a host thread at system scope, so process scope changes nothing
 - [Shared memory](../../../core/libs/prx/libkernel/File/src/SharedMemory.cpp) (libkernel) on Linux implements anonymous and named objects, bounded descriptor writes and seeks, and `shm_unlink` with effective read/write permission checks from FreeBSD 11. Named paths up to 1023 bytes use `/anyps5-shm-` plus SHA-1; collisions are not detected, and the namespace is shared across processes in the host mount namespace. Named creation applies the guest umask without changing the host mask. Linux procfs and `/dev/shm` are required. Operations use an advisory directory lock; external host operations bypass it, unrelated objects serialize, and descriptor operations require two spare host descriptors and compare device/inode with the initial descriptor identity on both the pinned-object and ordinary-file fallback paths. [Guest mappings](../../../core/libs/prx/libkernel/DirectMemory/PosixMemory.cpp) support shared and private mappings of these descriptors through the allocation tracker and pin a duplicate descriptor during validation and mapping; mapping requires one spare host descriptor; file-backed mappings use the write-watch scan fallback because aliases and descriptor writes bypass per-mapping tracking. On Windows, anonymous objects are delete-on-close temporary files and `mmap` maps them as [regular files](../../../core/libs/prx/libkernel/DirectMemory/PosixMemory.cpp); named objects remain unsupported. Invalid non-null name pointers, console behaviour and title compatibility remain unverified.
 - [sceKernelAddReadEvent and sceKernelAddWriteEvent](../../../core/libs/prx/libkernel/Equeue/Equeue.cpp) (libkernel): a read event on a listening socket, here and in `kevent`, reports the number of completed connections waiting to be accepted in `data`, as FreeBSD 11.4's [`filt_solisten`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/kern/uipc_socket.c#L3384-L3392) reports `so_qlen`: on Linux a TCP listener's accept queue from `TCP_INFO` (`tcpi_unacked`, which Linux fills with the accept backlog for a listening socket), and elsewhere, or for a listener that is not TCP, 1 while a connection is waiting, as no host call reports that count. A write event reports the free space of the socket's send buffer in `data`, as FreeBSD 11.4's [`filt_sowrite`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/kern/uipc_socket.c#L3358-L3382) reports `sbspace`: on Linux the host's `SO_SNDBUF` less the bytes `SIOCOUTQ` counts as queued, which include the host's per-packet overhead, so the space shrinks by somewhat more than the bytes sent. Windows has no query for that space and macOS is not wired up, so both report the whole `SO_SNDBUF`, which does not shrink as data is queued. Only guest sockets are supported; other descriptors and a low watermark above 1 throw
 - [sceKernelAddReadEvent on pipes](../../../core/libs/prx/libkernel/Equeue/Equeue.cpp) (libkernel) is the one exception to the sockets-only rule above: it also takes the read end of a pipe, as `kevent` does through FreeBSD's `filt_piperead`, and ignores the size argument there. Host streams, other descriptors and a write event on a pipe throw