Compatibility Modes in OpenPS2Loader

**izdubar** · 01-05-2010,11:58 AM

This topic is to gather various informations (most are taken from Jimmi answers) concerning the different compatibility modes available in Open PS2 Loader, and how to use them:

MODE 1 ("Load alt. core"):
Load the EE core at LOWER address (0x90000) but uses a g_buf (used for IOP resets) at higher address (0x1700000). The normal core loads at 0xe80000 and uses a g_buf at 0x88000. It is used because some games are overlapping normal core memory area (Sonic Unleashed loads at 0xd0000).

No speed difference caused by this mode.

This mode fixes some games that freezes on green screen

MODE 2 ("Alternative data read method"):
cdvdman module uses an alternative method to read data, not using semaphores.

Some games requires it.

MODE 3 ("Unhook Syscalls"):
Similar to HDL's mode 3: it disable IOP resets hooking.

MODE 4 ("0 PSS mode"):
This mode tries to make .PSS file some dummies. This mode help to run Max Payne through USB (timing issue with videos causing crash), and can be useful if the game contain a lot some PSS file you want to skip.

This mode fixes some games that freezes due to timing issue with videos
This mode can be used to skip PSS videos

MODE 5 ("Disable DVD-DL"):
A bit like HDL mode 2, it disable the DVD DL support, Jimmi implemented this mainly because to handle DVD9 it read after last ISO sector, to see if it find a 2nd layer.
With the eventuality the last sector of the ISO is also the last physical sector of the disk it could freeze.

MODE 6 ("Disable IGR"):
If activated, the In-Game-Reset functionnality is disabled. Use this mode for the few incompatible game with IGR.

MODE 7 ("Reduced cdvdfsv buffer"):
Reduce the buffers used by cdvdman/cdvdfsv. This helps to solve the problem with game being short in IOP memory (usually in SMB mode), ex: ICO (SCUS_971.59), Disgaea, ...

MODE 8 ("Hide dev9 module"):
A bit like "Disable Network support" mode of some HDL versions. This mode is needed for online gaming with some games (NFS Underground 2)

UDMA/MDMA MODE: Only concerning the IDE HDD, their purpose is to set the transfer mode that will have an impact on speed.

Some open questions:

are some mode to be tested alone (incompatible with some other) ?
or on the contrary are so modes to be tested together with another ?
is there any "scheme" to follow when a game doesn't work ?

**barf** · 01-05-2010,01:17 PM

MDMA/UDMA are 2 different modes to read from internal HDD, in addition there are different speeds for the two modes.

Here is some info.

**izdubar** · 01-14-2010,06:20 AM

I'd like to revive the subject.

According to your link, most of the information are related to HDL. Here what I think is useful:

Originally Posted by barf

MDMA & UMDA (Multiword DMA and Ultra DMA): the HD "talks" with the hardware in several ways. To be able to let the PS2 hardware think it's reading a DVD and not a HD backup copy (since it seems that some games rely on the speed at which the data are read) we have to say to the HD to speak like, as much as possibile, a PS2 DVD drive (that means SLOWLY). MDMA and UDMA are two of the possible ways to make the HD "talk" with a hardware (in this case the PS2) used as an option to slow down the speed (you cannot obviously use them together).

UDMA0 = 16.6 MB/s, MDMA0 = 4.2 MB/s

Also, I've read on some other post, that for some games freezing on "green" screen, we should try one mode. Can someone give me the correct info ?

**Ishtar** · 01-14-2010,06:50 AM

Originally Posted by Gilgamesh88

Also, I've read on some other post, that for some games freezing on "green" screen, we should try one mode. Can someone give me the correct info ?

I would have to read the code again to check what green means but I think yes try mode 1 if you get stuck on a green screen... mode 1 loads at high EE ram address normal is low EE ram address at least I think thats what it does if I am wrong sorry I only glanced at that code a while ago that might be another mode...

**izdubar** · 01-14-2010,07:29 AM

Yes I know the difference offset for alt. core in loader.c, but I didn't knew the relation with the color scheme.

So I update the first post.

**Ishtar** · 01-14-2010,08:03 AM

I don't think mode 1 changes speeds at all and im sure its EE ram the loader uses for alt load in mode 1 not iop... I think mode 2 is lower iop mem cores more compatable but slower... (I could be wrong tho)

btw I am a fan of mesopotamian mythology given your nick if you know its history you could guess that much tho I prefered enkidu over gilgamesh :P

**izdubar** · 01-14-2010,08:38 AM

Originally Posted by Ishtar

I don't think mode 1 changes speeds at all and im sure its EE ram the loader uses for alt load in mode 1 not iop... I think mode 2 is lower iop mem cores more compatable but slower... (I could be wrong tho)

Ok, I try to correct the first post (maybe I don't need to try to be so precise in technical info, so I won't do errors

)

Originally Posted by Ishtar

btw I am a fan of mesopotamian mythology given your nick if you know its history you could guess that much tho I prefered enkidu over gilgamesh :P

It's seldom to met someone who know this kind of things, and of course I immediatly knew you were among them according to your nickname

I were about to comment you on this, but doing many things at the same time I forgot !

I also like a lot everything around the mesopotamian era, the babylonian kings, their myths, epic

**jimmikaelkael** · 01-14-2010,09:03 AM

MODE 1: Load the EE core at LOWER address (0x90000) but uses a g_buf(used for IOP resets) at higher address (0x1700000). The normal core loads at 0xe80000 and uses a g_buf at 0x88000.
This mode fixes some games that freezes on green screen, because some games are overlapping normal core memory area (Sonic Unleashed loads at 0xd0000).
No speed difference caused by this mode.

MODE 2:
cdvdman module uses an alternative method to read datas, not using semaphores.
Some games require it.

MODE 3:
Similar to HDL's mode 3: it disable IOP resets hooking.

MODE 4:
This mode tries to make .PSS file some dummies. This mode help to run Max Payne trough USB (timing issue with vids causing crash), and can be useful if the game contain a lot some PSS file you want to skip.

MODE 5:
A bit like HDL mode 2, it disable to DVD DL support, I implemented this mainly because to handle DVD9 I read after last ISO sector, to see if it find a 2nd layer.
With the eventuality the last sector of the ISO is also the last physical sector of the disk it could freeze.

UDMA/MDMA modes are only concerning the IDE HDD, their purpose is to set the transfer mode that will have an impact on speed.

**froid_san** · 01-14-2010,09:05 AM

i too wonder what those modes do or when to use them on testing games.

like "0 pss" i don;t know what it does, i tried it once on megaman x8, since i know it has pss movies in there but it still plays it

**izdubar** · 01-14-2010,09:55 AM

Thanks a lot Jimmi for the explanation.

A few questions I have in mind right now:

As we're speaking of speed for mode 1, there was a controversial info about the impact of mode 2. Some says it may help for stuttering FMVs, and some says it is slower ?
For mode 3, just to understand in what situation this mode could help. I feel like this mode can be useful for multi-elf games ? Is it correct ?
For mode 5, if we (the user during test) know the game is not a DL, does it mean we can't set it on without harming anything else ? Also according to the description, I don't understand for which mode it is applicable (USB/ETH/HDD) ?

Thanks in andvance

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