PS4 platform notes

What the console, the OpenOrbis toolchain and the PacBrew libraries require, and how Playfin deals with it.

Startup, memory and exit

The sandbox refuses mkdir on / and /data: makeDirs only creates the folders below the data root. The data folder is created 0777 (with 0755 no file could be created in it).
musl's malloc maps 2600 MiB of system flexible memory on first use and calls sceLibcMspaceMalloc with a null mspace when that fails (crash CE-34878-0 on the first allocation). The fself needs the toolchain's default program authority id and auth info (--paid 0x3800000000000035 --authinfo …, cmake/ps4_pkg.cmake).
Returning from main ends in _exit, which the kernel refuses (SIGSYS): the app closes through sceSystemServiceLoadExec("exit").
The OpenOrbis linker script put only .data itself in .data: .data.* (statics of inline functions, musl's .data.__libc and stdio FILEs) and .init_array.* were dropped by create-fself and read as zero on the console. scripts/ps4/link.x collects them; scripts/check-ps4-eboot.py checks every build.

musl's headers carry Linux clock ids; the PS4 kernel (FreeBSD) reads CLOCK_MONOTONIC (1) as CLOCK_VIRTUAL (the process's CPU time), so timeouts never expired. clock_gettime comes from libkernel (patching musl does nothing): src/platform/ps4/clock_ps4.cpp, linked into the executable, translates the ids and calls sceKernelClockGettime.
musl gives SOCK_CLOEXEC/SOCK_NONBLOCK their Linux values; the kernel refuses such sockets ("Protocol not supported"). The executable is linked with --wrap=socket --wrap=socketpair (socket_ps4.cpp): the flags are removed and non-blocking mode is set with fcntl.
musl's resolver reads the DNS servers with sceNetGetDnsInfo: libSceNet must be loaded (ORBIS_SYSMODULE_INTERNAL_NET, sceNetInit in backend::postInit), otherwise the first host name lookup calls an unresolved stub and the system kills the app.

Retail firmware has no runtime shader compiler (Piglet "OpenGL ES 2.0 Piglet", GL_SHADER_COMPILER 0), so NanoVG's GLES2 backend cannot run. The system's libScePrecompiledShaders.sprx exports compiled shaders loadable with glShaderBinary; swordfish/vpBasic + swordfish/fpAlphaTexture draw a texture upright with positions -1..1 and texture coordinates 0..1 (v = 0 at the top). Playfin draws everything with its software renderer and only presents the finished frame (and the video) through that pair (present_ps4.cpp).
A full 1920x1080 RGBA upload (glTexSubImage2D) takes about 2 ms.

mpv's software renderer must use swscale's fast paths (sws-fast=yes, sws-scaler=fast-bilinear, 3 ms per 1080p picture instead of 110 ms) and must not wait for each picture's display time (BLOCK_FOR_TARGET_TIME=0). FFmpeg counts one CPU on the PS4: vd-lavc-threads=4. 1080p H.264, HEVC, VP9 and AV1 then play at 24-25 fps; files above 40 Mbit/s or 1080p are transcoded by the server.
mpv 0.36 is built without Lua: it has no ytdl option (player::optionMayBeMissing).
There is no system font provider for libass: fonts come from resources/fonts, and scripts/ps4/libass/fallback.patch lets a character missing from the requested and default fonts come from any loaded font that has it (Japanese, Korean and Chinese from Noto Sans CJK).
A server trusted by its pinned self-signed certificate is streamed with tls-verify=no (FFmpeg cannot check a pin); servers with a CA-signed certificate are verified against resources/certs/cacert.pem.

sceImeDialogInit refuses the password option (0x04, error 0x80bc0030) unless the type is ORBIS_TYPE_BASIC_LATIN; with that type password, no learning (0x20) and no auto-capitalization (0x02) are accepted. Passwords typed on the PS4 keyboard are therefore ASCII only.
Without a signed-in user the keyboard cannot open; the app then falls back to its own editor.

The local time is the console's time zone plus its summer time setting, as they are now: a programme after a summer time change within the guide's three days shows an hour off.