A PS1 EBOOT now boots the installed firmware's POPS manager
(flash0:/kd/popsman.prx), which loads its PS1 emulator (pops_0Xg.prx) for
the game. Load_PSP_POPS stands in for the kernel's reboot into its POPS
configuration: it loads the manager and that configuration's user modules,
and a helper thread makes the kernel init's scePopsManLoadModule(path, 0)
call. InitForKernel reports a POPS boot from the memory stick.
The emulator plays its sound on the Media Engine, so a PS1 boot always
gets the emulated ME, whatever the homebrew setting says, and is refused
on platforms that can't emulate it. The manager boots the ME with its own
code (POPS's reboot has no me_wrapper, so Sony's ME firmware isn't booted
for it), and its ME loop runs there unchanged, playing through the audio
block.
Everything in POPS that reaches hardware registers is kernel code, so a
POPS boot leaves the ME's kernel mode stopgap (g_kernelModeAnywhere) off:
7% fewer host instructions in Crash Bandicoot.
The manager also drives the GE directly: its stall register and FINISH
status are an MMIO device that only answers during a POPS boot, and stall
writes extend the HLE GPU's current list.
The 6.60 and 6.61 popsman.prx and pops_01g/02g.prx have the same code. The
manager's is checked when it's loaded, and any other one fails the boot
with a message. Savestates include the boot's threads.
Reading a game's disc image needs the next two changes.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Yabause-PSP's me.prx ORs 0xA0000000 onto its own addresses to share a
buffer with the ME uncached, which is 0xA8xxxxxx for a module in kernel
RAM. The main CPU's space has no views there, so it crashed.
All of kernel segment 1 (0xA0000000-0xBFFFFFFF) now counts as MMIO, and a
device below the hardware registers maps RAM and VRAM onto their uncached
mirrors at 0x40000000. The main CPU's native kernel loads and stores send
the whole segment to that path; the ME keeps 0xBC000000 as the boundary,
since its space maps the rest.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The ME runs a slice behind the main CPU, so a main CPU polling a mailbox
in the boot page saw the ME's progress up to a slice late. Reading the
boot page now runs the ME up to where the main CPU is in its slice first,
and the end of the slice runs only the rest. me/audiofifo, which times
the ME's playing from the main CPU, read 43900Hz for 44100.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The audio hardware at 0xBE000000, as POPS's ME loop (popsman.prx +2F88)
drives it: after setting it up, it writes one stereo sample (left in the
low half) to 0x70 whenever status 0x28 bit 5 says the FIFO has room,
and sleeps in halt in between on the ME's interrupt source 12. Measured
from the ME on a PSP-1000 (pspautotest me/audiofifo): the FIFO holds 24
samples and plays them at 44.1kHz while 0x04 bit 1 is set; status 0x28
has bit 4 while playing, bit 5 while there's room, and bit 1 once it has
played out its last sample, a sample after the FIFO empties; and source
12 is a level, up while there's room, which halt wakes on with
interrupts disabled. What it plays is mixed into the output.
A halted ME used to sleep until the main CPU's next slice. It now wakes
within the slice when the full FIFO next has room, as POPS's loop sleeps
for every sample.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
MIST (and psp-media-engine-safe-task, and NJEMU through it) restart the
ME through me_wrapper's bootstrap at 0xBFC00040, after patching it to
point a0 at main RAM, which makes the firmware take its resume-from-
sleep path: restore eDRAM from a0 and go back to the main loop. They
then put a task's address in the firmware's command table with
DMACplus and send a command with the soft interrupt.
- The boot now leaves a bootstrap with 6.61's layout at 0xBFC00040,
and a stand-in for me_wrapper's ME stub (which isn't loaded under
HLE) that runs the image.
- The firmware never sets Status.IE: it gates interrupts with mtic
alone, so either one enables them now. Its main loop enables them for
only a few instructions, so mtic takes a pending one right away.
- Opcode 0x2C, which the resume path runs, is a no-op on the ME.
- Sysreg 0x00 reads 0 (the bootstrap's debug handler check), 0x70 is
kept, and the DDR flush register (0xBD000004) is always done.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The ME's startup code (custom-core, libmecore) sets them, and Sony's ME
firmware lowers them around its halt. Only kept, like the other ME
devices, and only while the ME is emulated.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
What the firmware sets up for the ME at boot, which mcidclan's custom-core
libraries rely on, at kernel init when the ME is emulated:
- Sony's ME image at 0x88300000, as me_wrapper loads it: meimg.img on a
PSP-1000, me_t2img.img on later models, from the installed firmware's
flash0:/kd/resource, decrypted and KL4E-decompressed (only the first of
its two streams, the code). Custom-core calls functions in it, picking
per-model address tables by the word at 0x18. Without the firmware it's
logged and left out.
- A "SceMeRpc" sysevent handler record, which sceKernelReferSysEventHandler
(new, sceSysEventForKernel) returns, and custom-core takes over.
Also the VME's control registers (0xBCC00000), kept, with the status at
0x10 reading as done: custom-core's ME startup writes 1 there and waits.
mcidclan's custom-core poc, hw-mutex, gu-shared-list and exceptions
samples now run.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The calls homebrew starts the ME with (1.50's NIDs, and 3.71's for the
ME's reset and bus clock) set or clear a bit of the reset or bus clock
register the way the firmware's driver does, returning whether it was
set. Only those NIDs, so a later firmware's lowio.prx keeps its own
exports under --vsh.
Kernel modules copy their ME code to the boot page with SysclibForKernel's
memcpy, which now goes through MMIO for hardware addresses like the
replaced memcpy already did (MMIO::Copy, shared).
pspsdk's mebasic, MElib's test, PSP Bunny, snes9xTYL and ProTrekkr's test
now start their ME.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A PL080-like controller: channels 4-7 at 0xBC800180, run at once when
enabled, following linked list items of five words (source, destination,
next, control, configuration). Addresses are physical, and on the ME's
bus (a master bit in the control word) the low ones are its eDRAM.
Transfer size is in units of the source width. A finished channel with
its interrupt bit set shows in 0x04, cleared through 0x08.
0xBC800100-0x10C set the LCD's framebuffer, which goes to sceDisplay.
Pixel format 0 is 8888 (mcidclan's samples); others are logged. The
colour space conversion registers (0x120-0x160) are only kept so far.
Like the other ME devices, this answers only while the ME is emulated.
mcidclan's dmacplus-me2sc and sc2me-then-me2sc samples show their
transferred eDRAM.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Sysreg (0xBC100000) gets the ME's reset bit (0x4C bit 2), the soft
interrupt (0x44, which interrupts the other CPU: the ME's controller from
the main CPU, PSP_MECODEC_INTR from the ME), the hardware mutex (0x48,
each CPU sets its own bit only while the other's is clear) and the clock
and config registers it writes. The ME's interrupt controller (0xBC300000,
write-1-to-clear, mask at 8) answers the ME only. All of it is the ME's
state and stays unhandled without an ME.
On the ME: interrupts to EBase with EPC and EXL, halt sleeping until an
unmasked interrupt, and Count, which doesn't run: it stays 0 across 10ms
with ERL set after reset and with Status cleared, and reads back what was
written. Reset keeps the GPRs and sets Status ERL/BEV/SR, which homebrew
relies on: mcidclan's samples run C on the stack Sony's ME code left. The
values are from a kernel probe on a PSP-1000 (sp 0x801FFFE0, COP0 22 = 1,
Status 0x20500404, mfic 0, which doesn't gate interrupts).
The main CPU runs base interrupt handlers the way interruptman calls them
(a0 intno, a1 arg, a2 interrupted pc; -2 disables), and interrupt 31 has
a stand-in for me_wrapper's handler, which homebrew releases first.
While the ME is emulated, any main CPU code may access hardware registers:
homebrew calls its own code in kernel mode through a kcall module. This
is a stopgap (g_kernelModeAnywhere, marked HACK): kernel mode should be
part of the CPU's state, switched on while a kernel module's export runs.
The memcpy/memmove replacements copy through MMIO when an end is a
register address, for code copied to the boot page.
mcidclan's me-soft-interrupt sample now runs, counting each interrupt in
both directions.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
MeCore owns a second MIPSState in the ME's address space, held in reset
until released (SetReset). It runs on the interpreter, a slice behind the
main CPU: CoreTiming runs it for the cycles the main CPU has just used, in
Advance and ForceCheck. Its own PRId (COP0 22) and mfic/mtic flag; MMIO
counts as kernel mode on it, and a syscall stops it with an error rather
than reaching HLE. The interpreter's block stepping reads delay slots
through the stepping CPU's memory, and cache instructions log at verbose
level, as ME code flushes its caches in a loop.
Created at boot only for homebrew (PBP with MG category or no SFO, ELF;
the VSH counts, as vshmain.prx loads as an ELF), when "Enable ME
emulation for homebrew" is on: a global checkbox in developer settings,
off by default and not translated yet, or --me-core. Saved in its own
section after MMIO (SaveStart v5), with its own memory; loading a state
creates or removes the ME to match.
The boot page now starts with a reset stub that sends the ME on to
0xBFC00040, where homebrew puts its code (from the firmware's reset code,
read on a PSP-1000).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The ME sees the main CPU's RAM, but has its own eDRAM at 0 (with
0x80000000 and 0xA0000000 mirrors) where the main CPU has its scratchpad,
its own memory where the main CPU has VRAM, and both CPUs share the boot
page at 0xBFC00000.
- The ME's own memory is views in the main arena flagged MV_ME_ONLY, which
only Memory::CreateMESpace() maps, into a second reservation along with
the shared views at their same arena positions. It gets its own block
shadow.
- The eDRAM (MV_EDRAM) is the ME's half of the eDRAM chip, the GE's VRAM
being the other: 2MB on the PSP-1000 (whose resident ME image says so),
4MB on the others (from mcidclan's libmecore, not hardware-checked).
- At VRAM's addresses, through 0x44000000 and 0xA4000000 alike, the ME
doesn't see VRAM but memory of its own (pspautotest me/vram, on a
PSP-1000): where homebrew keeps the VME's buffers. Its size isn't known;
2MB with VRAM's mirrors here, and no depth layout on 16-bit accesses.
- 0xA0000000 reaches physical memory uncached, so RAM is mapped at
0xA8000000 too.
- The boot page is a view too, which the main CPU reaches through a new
MMIO device (in savestates from MMIO section version 2). The ME runs
code from it, uncached, so the main CPU's writes invalidate code there.
On masked platforms it isn't mapped, and the device uses a plain
buffer.
- AddressSpace has IsValidAddress etc, with the ME's rules when edramSize
is set, and the interpreters and the IR interpreter check and fetch
instructions through their state's space. The IR compiler's checks still
use the main CPU's, until the ME gets a JIT.
- On Darwin, MemArena can hold several view reservations.
Masked platforms (iOS, 32-bit) don't get an ME space yet.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Kernel code's loads and stores may reach hardware registers, which only the
interpreter handled, so the IR frontend sent every one of them (in kernel
blocks, only run by the VSH boot) to it.
They now become LoadKernel*/StoreKernel* IR ops (one per size, like the
plain loads and stores), which check at run time whether the address is
memory or a hardware register (MMIO). After constant
propagation, ResolveKernelMemory turns the ones at a constant address that's
plain memory into ordinary loads and stores, so only the hardware registers,
and addresses only known at run time, stay checked. The native JITs run the
two ops through their IR fallback. They're barriers, since a register access
has side effects, but can't change the GPRs, so constants stay known across.
The kernel mode check for MMIO moves to the interpreter, the only caller that
can run user code there. TestMMIO covers the new paths and which accesses
stay checked. Under --vsh, the JIT and the interpreter now make the same
unhandled register accesses, in the same numbers.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The interpreter's MMIO dispatch was a hardcoded chain for GPIO and the syscon
serial port. Devices now register an address range in Core/HW/MMIO and get
each access with its width and the MIPSState making it, for registers that
answer each CPU differently. An access no device handles is logged and reads
as poison, as before.
GPIO and syscon serial become the first two devices. They're reset at boot,
which they never were, and saved in savestates (SaveStart section version 4).
ll/sc, lwl/lwr and lwc1/swc1 reach MMIO in the interpreter too, and kernel
blocks leave lwc1/swc1 to it like the other loads and stores. swl/swr and
lv/sv still treat it as a bad address. TestMMIO runs a kernel-mode access on
each core and the registers through a savestate.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
