Bug: Gran Turismo 5/6 desyncs

[Satan86]

Gran Turismo games are very unstable on RPCS3, they all have random softlocks. The only setting that "helps" is using PPU/SPU interpreters which slows the game to a crawl to get a few extra minutes of gameplay.

There are two types of desyncs in these games:

• RSX desyncs: When the screen freezes but the game is still running in the background. Happens a lot in CPUs without TSX instructions, Accurate RSX Reservations helps if your CPU is good, but if it's weak and lacks TSX, you'll have them all the time.
• SPU desyncs: When the graphics still render but the game physics are frozen, so you get to see effects like smoke, rain, flashing lights and stuff like that still working, but the game and physics are frozen in time. Input doesn't work and sound is cut out. It's not specifically an SPU issue, as multiple game threads stop working, both on PPU and SPU.

SPU Desync Example

I've added logs for desyncs too, but they don't print any errors to the log file.

• Gran Turismo 5 Prologue
  This game is the most stable, you can play for quite a long time before getting a desync. It's SPU desyncs behave differently compared to the other two games, instead of freezing the physics and input, it only cuts out the audio. If it happens mid-race, you can finish it, but the game will then freeze at the next loading screen and won't save your progress.
  I didn't manage to make the game desync in time to get a log that isn't 2gb (it spams the log a lot), but here it is anyway RPCS3.log.gz

• Gran Turismo 5
  The first game to get SPU desyncs that actually immediately freeze gameplay, GT5 doesn't care much about how good your CPU is, desyncs may happen quickly or take hours. More cars in a race increases the chance of a quick desync, but if you're really dedicated you can finish the game. Here's the log file: RPCS3.log.gz

• Gran Turismo 6
  GT6 is the most unstable of them all, along with all other issues (especially in 1.22), desyncs run rampant, being difficult to finish a race without desyncing. It's SPU desyncs behave the same as GT5. Log file: RPCS3.log.gz

These tests were done with a Ryzen 5 5600x, GTX 1050 Ti running on Windows 10 21H1.

[illusion0001]

Did some tests, can cause it to desync consistently,

forcing 0x1936E65 to 0 for BCUS98114 01.00 will make it always desync.
In code, 0x01D094DC or 01D094F4. li either 0 or 1 before stb will also do it.
During desync, ppu thread always stop at 1c75ae0 syscall

[elad335]

It's a longshot, but please test with #13631.

[Shoegzer]

Tested Gran Turismo 5 [BCUS98114], patched to 2.17, with #13631. Unfortunately, this did not resolve the issue. Desyncs now occur immediately at start of a race, as opposed to within 10-30 seconds on master.

Tested with settings per the wiki and also defaults.

Log: RPCS3.log.zip

[steven88ita]

I attached three logs

this is when crashed at start:
RPCS3 crash start.log.gz
this is when audio cuts (happens very often):
RPCS3 (audio cuts).log.gz
this when the game froze:
RPCS3.log(game freeze).gz

all them I have stopped the emulation few seconds after occurring, in a 3-5 minutes logs after running rpcs3, hope it helps to developers

[Canvas02]

Here is my log from GT5 prologue, after the sound cuts off
RPCS3.log.gz

[hoholee12]

rsx desync still occasionally happens on latest master. Only for GT5, I haven't encountered any freezes on GT6 however.

[ameenross]

rsx desync still occasionally happens on latest master. Only for GT5, I haven't encountered any freezes on GT6 however.

I can second that. Apparently I have no TSX instructions, but my CPU is definitely powerful enough. I can run a race for 2 laps just fine at about 40 FPS until it desyncs.

GT6 is quite stable, although it does require "Force CPU blit" to prevent flickering. Framerate is a little bit lower, but quite playable.