If your computer is already booting in EFI mode, chances are the ESP is mounted at /boot/efi. If you’re uncertain of this, though, you can try typing df /boot/efi at a shell prompt. If your ESP is mounted at this location, it will show up as a separate mount point:
$ df /boot/efi
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 201633 33104 168530 17% /boot/efi
Note: Although /boot/efi is the most common mount point for the ESP, other mount points are possible. Some users like to mount the ESP at /boot because this practice causes Linux kernels to be automatically placed on the ESP, which is useful if you’re using ELILO or the kernel’s EFI stub loader (often in conjunction with rEFInd or gummiboot). On the other hand, mounting the ESP at /boot will complicate kernel upgrades if your package system creates symbolic links within /boot. Some versions of Ubuntu do this, so mounting the ESP at /boot is undesirable with Ubuntu.
This example shows /dev/sda1 mounted at /boot/efi. The ESP is usually /dev/sda1, but this isn’t always the case, so if you see another partition specified, it might still be correct. If your ESP is not mounted, the df command may show /boot or / under the Mounted on column; or it may return an error message to the effect that there is no such file or directory as /boot/efi. If df showed that the ESP was not mounted, then you should mount it (after creating the /boot/efi mount point, if necessary), but you’ll need to know what partition to mount. You can use parted to view the partitions on your disk: