[General Omni Discussion] Entropy512:
Yes, all of the 4210 devices have had piles of weird issues, and they are common to all devices. I think it's been on the order of a year since I saw an issue that only affected one of the devices. (Specifically, it was a kernel mismerge in some display init stuff that only affected some I9100 units.) Oh yeah, an audio merge into the kernel broke I777 for a bit by reverting out some of our old I777-specific fixes (micswap)

And as far as enabling TRIM - the cost of mistakes are too high here. If we had a way to resurrect the devices I'd be willing to take the risk (see below)

Back in the early days of Superbrick, there were some reports of people Superbricking on bone stock firmwares, indicating TRIM/insecure erase might not be as safe as Samsung implied. It was extremely rare, but the fact that it EVER happened means I'm not risking it unless there's a way to recover it - which there isn't.

The issue is that at a low level, the Exynos 4210 does have secure boot. The silicon will not boot a first-stage bootloader unless it has been signed by Samsung. (That bootloader then performs signature checks only for the purposes of the infamous "triangle" - e.g. it checks and flags unsigned kernels but does not deny execution. So while in general the 4210 family is regarded as having an unlocked bootloader - it does have partial locking and this partial locking completely blocks "alternative" methods of booting the device other than JTAG.)

To boot the 4210 from USB, you need a USB-enabled first-stage bootloader that was signed by Samsung. This existed for the Exynos3 (aka "hummingbird") family and was what Adam Outler's "Unbrickable" mod used. A similar component that in theory allows booting from external SD existed for 4412 devices, but work with this led to some sort of barriers (I don't know what). Part of the reason otter (Kindle Fire) could enable TRIM was because otters can be USB-booted as they use GP (general purpose) instead of HS (high security) OMAP chips - they're the only devices known to exist where anyone has resurrected from Superbrick. If we had the ability to USB-boot a device with corrupted/nonexistent bootloader, I'd be willing to experiment with dangerous things that could trigger Superbrick.

To use Odin, the PBL+SBL (contents of the eMMC boot partition) have to be intact. The Superbrick repair methodology fully erases the whole chip - including this boot partition.

JTAG would in theory work, I tried to provide Hashcode's results to some of the JTAG houses but never heard back from them.

d710 has a completely different modem, but I've seen lots of reports of baseband issues with all of the non-Sprint variants too

No, what I mean is, there used to be two AOSP kernels:

https://github.com/cyanogenmod/android_kernel_samsung_smdk4210/ - 4210 devices only, and has not been updated since 4.2 (CM10.1)

https://github.com/omnirom/android_kernel_samsung_smdk4412/ - 4412 devices for CM10.1 and below, 4412+4210 for CM10.2 and later, along with all Omni releases

I suspect that this weird behavior somehow traces back to a mistake made during that merge process.

So a possible investigation route would be to try and backport the things needed to boot 4.4 into the old smdk4210 kernel. (Main thing here would be GPU drivers, probably a few other things.)