HuntsMan75 wrote:
...However, I also thought that kexts could be signed using a developer account and registering it with Apple. That's what I though anyway. I know a regular application can do that but a fair number of developers don't do it.
I think you are correct. But according to Cindori, "Have you ever wondered why disk manufacturers like Corsair, Samsung etc. have never written a Trim driver for OS X?...The reason is that Apple is keeping the AHCI driver private, making it impossible for anyone, even these big companies, to create a driver for SSD’s. So the issue is not that Apple “doesn’t allow Trim Enabler”, but that they don’t allow anyone to create AHCI drivers." So signing the kext would be the easy part. The current AHCI driver for TRIM works very well with third party SSDs but only after its test for Apple branding of the installed SSD is disabled, which is what TRIM Enabler does; that breaks the kext's signing, which Yosemite checks for, and if the signing is broken, when Yosemite's signing check is next turned on, that breaks Yosemite.
Checking for kext signing is a good thing, but so is having TRIM functional, so it's a choice that had to be made with the advent of Yosemite (and probably subsequent versions of OS X). The difference is that careful and knowledgeable installation of software can, and already has reduced the likelihood of installing things like MacKeeper (I've gotten phone calls telling me my Windows computer has a virus ["how come you can tell from a distance I have a virus but you can't tell that I have OS X?"]), but nothing the user can do will provide the SSD controller what TRIM does except turning the kext signing test off and TRIM on, via TRIM Enabler.
The risk there is breaking Yosemite, and Cindori's instructions on how to back out of that if it happens work but need a level of sophistication to implement that I suspect an experienced Mac user can manage but perhaps not someone drawn to the Mac by his or her iPhone experience. (Locally, there has been an upsurge in car break-ins and thefts and the solution the authorities have is to put placards on windshields to remind drivers not to leave ignition keys or money visible in their cars - what's the equivalent in cautious computing?) Indeed, I think the best way to be prepared for that eventuality is to create a bootable Yosemite installation on a Flash drive, then copy the Terminal commands in Cindori's instructions to a TextEdit document, substituting the Volume name of your boot drive in each command. Then, recognizing and remembering the risk, for any OS update (e.g., 10.10.1 to 10.10.2) or test or fix that changes the PRAM, use TRIM Enabler to turn TRIM off and the kext signing test back on first. If it breaks anyway, boot from the Yosemite flash drive you prepared and follow the customized instructions you also prepared to get running again.
It's a pain, as is locking your car and taking your keys, but less so than having your car stolen or your SSD working harder than it needs to.