Comment by zamadatix
4 years ago
The cability provides for a lot more than blocking software downgrades e.g. setting the boot signing key and then locking it with an efuse so only matching signed images can be booted or the inverse, enable unsigned custom firmware but blow a fuse to mark the device has been allowed to run custom software (which may impact hardware DRM systems during boot).
I already understood that it allows companies to be user-hostile, that's not what I'm asking about. I'm asking how it makes it simpler/cheaper for the company to maintain installed base versions.
Because it allows them to lock in a signing key and manage custom user images. Regardless if you feel that is user hostile or not it does make it simpler/cheaper for the company to manage the installed versions. The only thing they ever need to validate and support is for is upgrading to their images the way they have specified.
So companies could simply not "validate and support" custom user images as general company policy, but instead they resort to design and manufacture chips with the company policy and financial model embedded in the hardware. I think GP is asking why does this make any economical sense?
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