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Is there some way to know the arguments passed to xnu at boot from within the system?

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You can use the nvram utility.

Open and run nvram -p to see all the boot parameters. You can also run man nvram to see all the options. Note that to set any parameters you will have to use sudo if you are not logged in as root.

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But that only tells what is in nvram (which may have been changed since boot), right? – jhfrontz Jan 8 at 16:10
@jhfrontz the contents of the NVRAM don't change radically from boot time to the time you login. If you read the contents its mostly just various states the system wants to maintain between boots. The biggest changes occur when you start changing the system configuration. – CyberSkull Jan 8 at 16:17
right; I'm just thinking of the /proc/cmdline feature of linux (…) where you can get the arguments that were in effect at boot time (even if the boot configuration was changed subsequent to the last reboot -- something that happens a lot in my environment). I'm assuming there is something similar for MacOS but I'm having trouble finding it. – jhfrontz Jan 10 at 22:18

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