root@Debian:~# lsmod | grep efi
root@Debian:~# modprobe efivars
modprobe: ERROR: could not insert 'efivars': No such device
root@Debian:~# modprobe efivarfs
root@Debian:~# dmesg | grep -i efi
[ 0.000000] efi: EFI v2.40 by American Megatrends
[ 0.000000] efi: ACPI 2.0=0xdb728000 ACPI=0xdb728000 SMBIOS=0xdce2d998
[ 0.000000] efi: No EFI runtime due to 32/64-bit mismatch with kernel
[ 0.000000] efi: mem00: type=7, attr=0xf, range=[0x0000000000000000-0x0000000000058000) (0MB)
[ 0.000000] efi: mem01: type=0, attr=0xf, range=[0x0000000000058000-0x0000000000059000) (0MB)
[ 0.000000] efi: mem02: type=7, attr=0xf, range=[0x0000000000059000-0x000000000009e000) (0MB)
[ 0.000000] efi: mem03: type=0, attr=0xf, range=[0x000000000009e000-0x00000000000a0000) (0MB)
[ 0.000000] efi: mem04: type=2, attr=0xf, range=[0x0000000000100000-0x0000000000af2000) (9MB)
[ 0.000000] efi: mem05: type=7, attr=0xf, range=[0x0000000000af2000-0x0000000010000000) (245MB)
[ 0.000000] efi: mem06: type=3, attr=0xf, range=[0x0000000010000000-0x000000001000b000) (0MB)
[ 0.000000] efi: mem07: type=7, attr=0xf, range=[0x000000001000b000-0x0000000036412000) (612MB)
[ 0.000000] efi: mem08: type=2, attr=0xf, range=[0x0000000036412000-0x0000000037201000) (13MB)
[ 0.000000] efi: mem09: type=7, attr=0xf, range=[0x0000000037201000-0x0000000096e23000) (1532MB)
[ 0.000000] efi: mem10: type=2, attr=0xf, range=[0x0000000096e23000-0x00000000cbae0000) (844MB)
[ 0.000000] efi: mem11: type=4, attr=0xf, range=[0x00000000cbae0000-0x00000000cbb20000) (0MB)
[ 0.000000] efi: mem12: type=7, attr=0xf, range=[0x00000000cbb20000-0x00000000d28aa000) (109MB)
[ 0.000000] efi: mem13: type=1, attr=0xf, range=[0x00000000d28aa000-0x00000000d28c8000) (0MB)
[ 0.000000] efi: mem14: type=4, attr=0xf, range=[0x00000000d28c8000-0x00000000d3768000) (14MB)
[ 0.000000] efi: mem15: type=6, attr=0x800000000000000f, range=[0x00000000d3768000-0x00000000d3aca000) (3MB)
[ 0.000000] efi: mem16: type=4, attr=0xf, range=[0x00000000d3aca000-0x00000000d3ad0000) (0MB)
[ 0.000000] efi: mem17: type=7, attr=0xf, range=[0x00000000d3ad0000-0x00000000d5f1a000) (36MB)
[ 0.000000] efi: mem18: type=4, attr=0xf, range=[0x00000000d5f1a000-0x00000000da463000) (69MB)
[ 0.000000] efi: mem19: type=7, attr=0xf, range=[0x00000000da463000-0x00000000da7d0000) (3MB)
[ 0.000000] efi: mem20: type=3, attr=0xf, range=[0x00000000da7d0000-0x00000000daa63000) (2MB)
[ 0.000000] efi: mem21: type=0, attr=0xf, range=[0x00000000daa63000-0x00000000daac2000) (0MB)
[ 0.000000] efi: mem22: type=7, attr=0xf, range=[0x00000000daac2000-0x00000000db2d8000) (8MB)
[ 0.000000] efi: mem23: type=2, attr=0xf, range=[0x00000000db2d8000-0x00000000db2e2000) (0MB)
[ 0.000000] efi: mem24: type=10, attr=0xf, range=[0x00000000db2e2000-0x00000000dc420000) (17MB)
[ 0.000000] efi: mem25: type=6, attr=0x800000000000000f, range=[0x00000000dc420000-0x00000000dcee5000) (10MB)
[ 0.000000] efi: mem26: type=5, attr=0x800000000000000f, range=[0x00000000dcee5000-0x00000000dcfff000) (1MB)
[ 0.000000] efi: mem27: type=4, attr=0xf, range=[0x00000000dcfff000-0x00000000dd000000) (0MB)
[ 0.000000] efi: mem28: type=7, attr=0xf, range=[0x0000000100000000-0x000000021f000000) (4592MB)
[ 0.000000] efi: mem29: type=0, attr=0x0, range=[0x00000000dd800000-0x00000000e0000000) (40MB)
[ 0.000000] efi: mem30: type=11, attr=0x8000000000000001, range=[0x00000000f8000000-0x00000000fc000000) (64MB)
[ 0.000000] efi: mem31: type=11, attr=0x8000000000000001, range=[0x00000000fec00000-0x00000000fec01000) (0MB)
[ 0.000000] efi: mem32: type=11, attr=0x8000000000000001, range=[0x00000000fed00000-0x00000000fed04000) (0MB)
[ 0.000000] efi: mem33: type=11, attr=0x8000000000000001, range=[0x00000000fed1c000-0x00000000fed20000) (0MB)
[ 0.000000] efi: mem34: type=11, attr=0x8000000000000001, range=[0x00000000fee00000-0x00000000fee01000) (0MB)
[ 0.000000] efi: mem35: type=11, attr=0x8000000000000001, range=[0x00000000ff000000-0x0000000100000000) (16MB)
[ 0.000000] ACPI: UEFI 0x00000000DB741C88 000042 (v01 00000000 00000000)
[ 0.000000] efi: efi: Setup done, disabling due to 32/64-bit mismatch
[ 1.886246] tsc: Refined TSC clocksource calibration: 2194.918 MHz
voilà l’exécution, je crois que “efivars” n’existe pas, mais par contre “efivarfs” a l’air de bien exister