Apple users are being warned that security measures introduced in OS X Yosemite can adversely affect performance if they are have a third-party solid state drive (SSD) fitted in their Mac.
The issue, which has come to light since Yosemite was released, concerns the Kernel Extension (Kext) signing capability that Apple has introduced in OS X Yosemite. This is intended to ensure that low level system drivers are approved and unaltered by malware, by blocking drivers without a valid signature.
However, a knock-on effect of this feature is that it can stop the Trim driver for third-party SSDs from running. This driver is required in order to enable an SSD to effectively perform garbage collection processes and keep the drive performing at an optimal level.
While third-party SSDs will still work with a Mac running Yosemite, users are likely to see performance gradually decline due to this issue, according to software firm Cindori Software, which develops a Trim Enabler SSD tool.
Cindori offers a workaround, which is to disable Kext signing before attempting to enable Trim on a third-party hard drive. The latest version of the tool is able to do this automatically, then restore the Kext-signing setting back to normal.
While this may not seem like much of an issue, vendors like Cindori that develop third-party solutions for the Mac regard it as an attempt by Apple to force users to only buy upgrades from Apple itself.
“Kext signing basically works by checking if all the drivers in the system are unaltered by a third party, or approved by Apple. If they have been modified, Yosemite will no longer load the driver. This is a means of enforcing security, but also a way for Apple to control what hardware that third-party developers can release OS X support for,” the firm wrote in an FAQ on its site.