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limbo43 is dumping a lot of Xbox USA stuff, but he's getting some different results than existing dumps, which leaves me worried about the different dumping methods that are used: Whether or not Xbox Backup Creator is a safe dumping method, and if FreeCell dumps discs correctly (without the Kreon drive injecting any data that shouldn't be there) regardless of the drive's (unlock) state.

The first one that wasn't matching is Need for Speed: Most Wanted: Black Edition: https://redump.info/disc/50146/
The previous dump by h0lylag was changed to red status because it was supposedly bad.. without a real confirmation or redump by either dumpers. I've sent h0lylag a pm, but I don't know if he'll ever be back to read it.

The second one is Toxic Grind: https://redump.info/disc/50472/ vs. https://redump.info/disc/49392/

We really need to determine which of the dumps is wrong and what's causing the difference (and possibly find a way to detect bad dumps), before we end up with hundreds of potentially bad dumps.

I'm able to dump with a Kreon and also with a 0800v3 using FreeCell or XBC. I'll check some discs with all combinations and compare them as soon as I've some spare time, but that'll only be PAL discs.

Other dumps are matching: https://redump.info/disc/49180/ so I guess only a couple discs are affected by whatever is causing this.

I took a look at the differences between my NFS dump and h0lylag's, and the only difference was about 12K of data immediately following the layerbreak. On h0lylag's dump that area was all 0's, and on mine it was random(?) data. I extracted both images and compared the files and they all are identical.

It made me wonder if he's using XBC or FreeCell. If he's using XBC he may have not noticed those sectors being 0'd out due to a read error (vs. being SS areas). But it looks like based on his posts he has a Kreon drive so it's almost certainly FreeCell. So not sure what happened here.

I haven't looked at the differences on Toxic Grind yet but will take a look.

Just to be clear, all of my dumps are via Kreon+FreeCell with only one exception (a disc that was scratched and was able to read properly in an 0800 drive w/XBC). I actually can't remember which disc that was right now but it wasn't NFS or Toxic Grind.

Alright, checking out Toxic Grind now. This time, it's my dump that has zeroes right after the layerbreak. Looking at Starshadow's copy, his has the random data. In this case it's sectors 1913776-1913795 that are the culprits.

But it gets worse... I just re-ripped it with FreeCell on the same drive and it didn't spit out zeroes for those sectors anymore. The data now is a 1:1 match for Starshadow's dump.

So something seems wrong with FreeCell here. I'm looking at the source code and it doesn't seem to do anything special that might cause this. The code has a simple approach to retrying after any drive errors (5 times) and failing out completely, so an error was not reported by the drive/firmware.

The current FreeCell source is here, for reference:
https://github.com/claunia/freecell/blob/master/main.cc

This is bad because it's not just my dumps that might be inconsistent. Although the zeroed area may vary in size, so far it appears to be localized to some number of sectors immediately following the layerbreak. I don't have a definitive guide to the data layout on the disc, but FreeCell just treats all that stuff as "game data" without differentiating any kind of special padding after the layerbreak. If anyone has additional info it'd be most helpful to debug this.

I'm going to scan all my dumps and check 2-3 sectors after layerbreak to see how many of them have zeroes...

There's also a small possibility there's a bug in the SS sector skipping code in FreeCell but that seems like it'd be deterministic.

Out of 167 sequential dumps with FreeCell, 31 of them have 0's in the area just after the layerbreak and arguably need to be redumped. That's 18.6% of all of my dumps, or nearly 1 in 5 dumps that have this behavior with FreeCell. Doesn't seem good.

It is likely many of the dumps on Redump need to be analyzed to check for this missing data.

Edit:

Looking in my bash history I can tell that all of these zero-padding-at-the-layerbreak happened on the same drive. I have three identical Kreon drives in my machine and have been dumping games with all three at the same time. So something is up with this specific drive--but it doesn't do it every time. As I mentioned above, I just used the faulty drive to re-dump Toxic Grind and the checksum matched this time.

So there's something up with one of my drives, and at least someone else's drive (h0lylag who dumped NFS and got the zero padding too)

Thanks for bringing us closer to a solution. I guess you should try to eject and re-insert the disc after closing XBC (for dumping the DMI/PFI/SS) and before starting FreeCell. If that by any chance fixes the problem, then we need to add a check to FreeCell to make sure that the drive is in the correct mode/state before dumping. Otherwise it might be a firmware bug?

Also, it should be easy to find any other bad dumps if someone creates a tool to scan these sectors.

And it would be worth checking out if this issue also affects Xbox 360 in any way (!)

Jackal wrote:Thanks for bringing us closer to a solution. I guess you should try to eject and re-insert the disc after closing XBC (for dumping the DMI/PFI/SS) and before starting FreeCell. If that by any chance fixes the problem, then we need to add a check to FreeCell to make sure that the drive is in the correct mode/state before dumping. Otherwise it might be a firmware bug?

Also, it should be easy to find any other bad dumps if someone creates a tool to scan these sectors.

And it would be worth checking out if this issue also affects Xbox 360 in any way (!)

I don't think this would be related to ejecting because it only affected one of my drives, and the routine is identical for all three drives. It seems drive or firmware related.

I always dump my discs using a 0800v3 drive/XBC and a Kreon drive/FC. Never encoutered such a problem. The dumps always match each other, regardless which disc I've dumped (Xbox/Xbox360). Only XGD3 cannot be dumped using the Kreon.

Possibly relevant? /viewtopic.php?t=11435 … ergh-disc/