1) requires FOSS users to purchase a license from Microsoft to boot FOSS on affected machines that lack an appropriate Secure Boot override.
What "appropriate" Secure Boot overrides are available?
2) the end user is unable to modify the signed software
without a license from Microsoft, even though they have the source code available to them under the GPL.
Other parts of the posting imply that we have no idea what the software does, but thhe statement above says we have the source code. What am I misunderstanding?
1b) nuke the platform signing key and replace it with your own (iff the vendor lets you)
2) You're mixing things up. "We have no idea what the software does" refers to the hardware management code, which can run a full OS stack. But that quote refers to the tivoization "feature" of Secure Boot: you can recompile your software, but not run it on the hardware, because you lack the signing keys to make the machine trust your code. But, see 1)
What "appropriate" Secure Boot overrides are available?
2) the end user is unable to modify the signed software without a license from Microsoft, even though they have the source code available to them under the GPL.
Other parts of the posting imply that we have no idea what the software does, but thhe statement above says we have the source code. What am I misunderstanding?