Follow FreeBSD 11's do_sem_wait and do_sem_wake (COMPAT_FREEBSD9/10) on
a struct _usem: a wait sets _has_waiters, returns at once while _count
is non-zero and otherwise sleeps on the semaphore's queue; a wake clears
_has_waiters when one waiter is left and releases one waiter.
Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Operation 1 threw as unverified, so a title whose call_once path reaches it
stopped. In a payload process on a PS5 (firmware 12.70) operations 0 and 1
fail with EOPNOTSUPP and leave the word unchanged for every word tried,
as FreeBSD 11's __umtx_op_unimpl does. Answer operation 1 like operation 0.
Titles that ship their own libc.prx or Unity's PS5Util.prx import
_umtx_op (04AjkP0jO9U) for atomic waits, call_once and futex-style
waits. Implement UMTX_OP_WAIT, UMTX_OP_WAKE, UMTX_OP_WAIT_UINT,
UMTX_OP_WAIT_UINT_PRIVATE and UMTX_OP_WAKE_PRIVATE as FreeBSD 11's
kern_umtx.c does, on the sceKernelSyncOnAddressWait waiter queue.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HeC9bA3n74TzJRYv9AgBE8
A single global waiter lock serializes unrelated sceKernelSyncOnAddressWait/Wake calls. Hash the address into 64 cache-line-aligned buckets so unrelated waiters no longer contend, without changing wake semantics.
Wait8 and Wait16 compare the 1- or 2-byte value at the address with the
comparand and share the waiter queue of the other sizes.
sceKernelSyncOnAddressWake accepts any non-null address: libc's
__std_atomic_notify_one/all pass the atomic's own address, which for 8- and
16-bit atomics need not be 4-byte aligned.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
libc's __std_atomic_wait_direct_32 and __std_atomic_wait_direct_64
import these functions, so a libc.prx that contains the C++20 atomic
wait wrappers does not load without them. Wait32 compares a 4-byte
value and Wait64 the full 8-byte value. Both share the waiter queue
of sceKernelSyncOnAddressWait, so sceKernelSyncOnAddressWake releases
waiters of every size on the address. A null address, or one not
aligned to the value size, throws. The by-value comparand, the return
values and the 8-byte alignment of Wait64 are assumed and recorded in
TechnicalDebt.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
sceKernelSyncOnAddressWait parks the calling thread while the 32-bit word
at the address still holds the expected value, until
sceKernelSyncOnAddressWake releases it or the timeout expires.
sceKernelSyncOnAddressWake releases up to the requested number of threads
parked on the address, in arrival order.
The libc.prx bundled with SDK 9 titles imports both for its once
primitive, so those titles stopped at load with an unresolved import.
# Conflicts:
# docs/dev/TechnicalDebt.md
