Broken UEFI implementations

This page serves as a repository of information about any aspect of the system firmware which is broken on UEFI machines, but especially those directly related to UEFI itself.

BGRT Table

• BGRT is an ACPI table to tell us if and where UEFI firmware has drawn its logo on the screen. Technically the BGRT is an ACPI 5 table, but its use corresponds with UEFI 2.4 deployments, and it goes hand in hand with the EFI Graphics Output Protocol and ESRT + UEFI UpdateCapsule and [Microsoft's firmware update graphics capsule]. In theory, "uint16_t version" (offset 0x24) should always be 1, and "uint8_t status" (offset 0x25) with 0x1 set means "valid data" - that is, if the firmware displayed a splash graphic, it sets the values in the table and sets status to 1; if not, status should be 0.

Here are some sample entries. These are from real machines, but the problems are common across lots of hardware from lots of vendors:

Lenovo X1 Carbon (1st gen, 346035U)

00000000  42 47 52 54 38 00 00 00  00 00 4c 45 4e 4f 56 4f  |BGRT8.....LENOVO|<br>
00000010  54 50 2d 47 36 20 20 20  00 27 00 00 50 54 4c 20  |TP-G6   .'..PTL |<br>
00000020  02 00 00 00 00 00 01 00  18 b0 7e d3 00 00 00 00  |..........~.....|<br>
00000030  0f 02 00 00 b4 00 00 00                           |........|

This helpfully has version=0x0000 and status=0x01 i.e. some version that doesn't exist but the table claims its information is valid.

Intel strawberry mountain (DQ67SW)

00000000  42 47 52 54 38 00 00 00  01 fe 49 4e 53 59 44 45  |BGRT8.....INSYDE|<br>
00000010  4d 48 42 20 43 52 42 20  01 00 00 00 41 43 50 49  |MHB CRB ....ACPI|<br>
00000020  00 00 04 00 01 00 00 00  00 d0 fd a7 00 00 00 00  |................|<br>
00000030  fa 00 00 00 4f 00 00 00                           |....O...|

This particular firmware says it's version 1 but that the data is invalid; this implementation /always/ says the data is invalid, whether it displays the logo or not.