newfs TRIM flag device support

Hi,

I'm reading the newfs manual https://man.freebsd.org/cgi/man.cgi?newfs(8) to be able to know about the TRIM flag. In the manual under -t parameter, it mentioned about "underlying device support", what exactly is this device? Is it the host (for example, Raspberry Pi SD/eMMC host reader) or the SD/eMMC card (controller) or both?

-t

Turn  on	the TRIM enable	flag.  If enabled, and if the underly-
	ing device supports the BIO_DELETE  command,  the  file	system
	will  send  a  delete request to	the underlying device for each
	freed block.  The trim enable flag is typically set for	flash-
	memory devices to reduce	write amplification which reduces wear
	on write-limited	flash-memory and often improves	long-term per-
	formance.   Thinly provisioned storage also benefits by return-
	ing unused blocks to the	global pool.

BR,

orbit