Modding Using HostFS on PCSX2 (P3/P4/SMT3)

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Update 12/13/22: Clarified how to generate HostFS .pnach file now that resources have moved around on the site.

In our previous guide on modding Persona 3 and 4 (PS2), it was mentioned you’d need to use paid software UltraISO to repack your modified files into a new, bootable ISO. Thanks to new patches by TGE, repacking ISOs– and even CVMs– is finally a thing of the past.

While this method should work on any device or emulator that runs PS2 games (as long as there’s hostFS support and a way to boot from an ELF), this guide will mainly focus on PCSX2.

The only prerequisites are:

This method does not require you to modify your ISO at all! Instead, we’ll be using a code patch that makes the game load files over the local network (your computer’s filesystem) rather than the archives in the ISO. This method is 100% free, and results are pretty much instant every time you change a file, even while the game is running. So it has several advantages over the old method, which could take ~10 minutes to build a mod each time, even with optimal hardware.

1. Generating a .pnach File

The patch takes the form of a .pnach, a text file with a custom extension that the emulator loads code patches from.

  1. Go to ShrineFox.com/GetStarted
  2. Choose the platform (PS2)
  3. Choose the game
  4. Choose the region of your copy
  5. Check the boxes for any optional patches you want, and click the download button at the bottom of the page.

2. Activating Patch in PCSX2

  1. Place it in your PCSX2 cheats folder. Be sure to enable cheats in the emulator!
  2. Next, go to PCSX2’s inis folder and open PCSX2_vm.ini with your text editor. Change the line hostFS=disabled to hostFS=enabled then save and exit.
  3. Make a folder anywhere you want on your PC for the game.
  4. Open your ISO with 7zip and extract the file beginning with “SLUS” to your game folder. Add the .ELF extension to it.
    Note: 
    In Nocturne’s case, you also want to extract dds3.img, dds3.ddt, and the MOVIE folder.
  5. Set this folder as your output folder in the Mod Compendium’s settings and check the HostFS box (if you have an older version, you may need to redownload the latest one from here).

Now, when you build your mods, it’ll immediately output the files directly to this folder. No more waiting around for the Mod Compendium to extract your ISO and repack CVMs every time you make changes!

All that’s left to do is select your unmodified ISO in PCSX2, but instead of booting the typical way, we’re going to select Run ELF and choose our extracted ELF file. If the cheats were applied, you should hopefully notice the modifications have loaded. From now on, changing anything is as easy as hitting Build again the Mod Compendium.

For Nocturne, there is one extra series of steps to complete first-time setup.

  1. Download TGE’s DDS3Pack
  2. Move the .exe and .dll to the location of your extracted dds3.img file and open a command prompt at the location.
  3. Type the following and press enter: dds3pack unpack dds3.img
  4. You’ll want to rename the output folder dds3 to dds3data and move the previously extracted MOVIE folder inside.

That’s it! Now you can mod P3FES, P4 and Nocturne with instant changes by loading files externally instead of ever touching the ISO. Since your ISO remains unmodified, the game’s CRC never changes either– so there’s no longer any need to rename your cheat files each time you mod the game.

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5 thoughts on “Modding Using HostFS on PCSX2 (P3/P4/SMT3)”

  1. When I try and run with those same steps, the console starts spamming error like this.

    (Patch) Error Parsing: patch=1,EE,00223008,word,3C024340 (level up white glow)
    Maximum number of cheats reached
    (Patch) Error Parsing: patch=1,EE,00123430,word,24020BF6
    Maximum number of cheats reached
    (Patch) Error Parsing: patch=1,EE,0041751c,word,3c050000
    Maximum number of cheats reached
    (Patch) Error Parsing: patch=1,EE,00417524,word,3c060050
    Maximum number of cheats reached
    (Patch) Error Parsing: patch=1,EE,0041752c,word,3c070001
    Maximum number of cheats reached
    (Wide Screen Cheats DB) Patches Loaded: 0
    EE/iR5900-32 Recompiler Reset
    EE: Unrecognized op 74736f68
    GSdx Lookup CRC:DEDC3B71
    EE: Unrecognized op 1000001
    EE: Unrecognized op 1
    EE: Unrecognized op 1
    Trap exception at 0x01fffad0

    I don’t know if it has something to do with the extraction, or something

  2. After installing this PCSX2 runs out of memory and I get the error “SRD: sceOpen error = -5” just a few minutes after playing. Please help!

  3. This patch is broken after at least PCSX2 version 1.7.2641
    A PCSX2 dev is convinced it’s because the patch only accidentally worked before because PCSX2 has become more accurate in emulation

  4. Friendly reminder that this is not compatible with versions newer than 1.6.0 of PCSX2.

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