Linux kernel developers like to get support for new features — such as
filesystem types — merged quickly. In the case of the exFAT
filesystem, that didn’t happen; exFAT was created by Microsoft in 2006 for
use in larger flash-storage cards, but there has never been support in the
kernel for this filesystem. Microsoft’s recent announcement
that it wanted to get exFAT support into the mainline kernel would appear
to have removed the largest obstacle to Linux exFAT support. But, as is so
often the case, it seems that some challenges remain.

Source: LWN.net – [$] Examining exFAT