[PATCH v3 4/7] Documentation: gpu: nova-core: Document vbios layout

Joel Fernandes joelagnelf at nvidia.com
Thu Jul 3 15:49:23 UTC 2025



On 7/2/2025 8:20 PM, Bagas Sanjaya wrote:
> On Wed, Jul 02, 2025 at 08:00:41PM +0900, Alexandre Courbot wrote:
>> diff --git a/Documentation/gpu/nova/core/vbios.rst b/Documentation/gpu/nova/core/vbios.rst
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..55d7dd4a6658c2a20cc5617f96b278bc4ec2ba17
>> --- /dev/null
>> +++ b/Documentation/gpu/nova/core/vbios.rst
>> @@ -0,0 +1,180 @@
>> +.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>> +
>> +==========
>> +VBIOS
>> +==========
>> +This document describes the layout of the VBIOS image which is a series of concatenated
>> +images in the ROM of the GPU. The VBIOS is mirrored onto the BAR 0 space and is read
>> +by both Boot ROM firmware (also known as IFR or init-from-rom firmware) on the GPU to
>> +boot strap various microcontrollers (PMU, SEC, GSP) with critical initialization before
>
>    bootstrap
>
>> +the driver loads, as well as by the nova-core driver in the kernel to boot the GSP.
>> +
>> +The format of the images in the ROM follow the "BIOS Specification" part of the
>> +PCI specification, with Nvidia-specific extensions. The ROM images of type FwSec
>> +are the ones that contain Falcon ucode and what we are mainly looking for.
>> +
>> +As an example, the following are the different image types that can be found in the
>> +VBIOS of an Ampere GA102 GPU which is supported by the nova-core driver.
>> +
>> +- PciAt Image (Type 0x00) - This is the standard PCI BIOS image, whose name
>> +  likely comes from the "IBM PC/AT" architecture.
>> +
>> +- EFI Image (Type 0x03) - This is the EFI BIOS image. It contains the UEFI GOP
>> +  driver that is used to display UEFI graphics output.
>> +
>> +- First FwSec Image (Type 0xE0) - The first FwSec image (Secure Firmware)
>> +
>> +- Second FwSec Image (Type 0xE0) - The second FwSec image (Secure Firmware)
>> +  contains various different microcodes (also known as an applications) that do
>
>               various microcodes?

The above 2 fixups sounds good to me, I'm guessing Danilo if you're pulling this
then maybe apply the fixups directly to the patch since it is trivial?

> 
>> +
>> +.. note::
>> +   This diagram is created based on an GA-102 Ampere GPU as an example and could
>> +   vary for future or other GPUs.
>> +
>> +Here is a block diagram of the VBIOS layout::
> 
> Above sentence (but not the note directive) is redundant, though.

This suggestion I'd skip.

But thanks for all the review!

 - Joel


> 
>> +
>> +    +----------------------------------------------------------------------------+
>> +    | VBIOS (Starting at ROM_OFFSET: 0x300000)                                   |
>> +    +----------------------------------------------------------------------------+
>> +    | +-----------------------------------------------+                          |
>> +    | | PciAt Image (Type 0x00)                       |                          |
>> +    | +-----------------------------------------------+                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | ROM Header        |                         |                          |
>> +    | | | (Signature 0xAA55)|                         |                          |
>> +    | | +-------------------+                         |                          |
>> +    | |         | rom header's pci_data_struct_offset |                          |
>> +    | |         | points to the PCIR structure        |                          |
>> +    | |         V                                     |                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | PCIR Structure    |                         |                          |
>> +    | | | (Signature "PCIR")|                         |                          |
>> +    | | | last_image: 0x80  |                         |                          |
>> +    | | | image_len: size   |                         |                          |
>> +    | | | in 512-byte units |                         |                          |
>> +    | | +-------------------+                         |                          |
>> +    | |         |                                     |                          |
>> +    | |         | NPDE immediately follows PCIR       |                          |
>> +    | |         V                                     |                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | NPDE Structure    |                         |                          |
>> +    | | | (Signature "NPDE")|                         |                          |
>> +    | | | last_image: 0x00  |                         |                          |
>> +    | | +-------------------+                         |                          |
>> +    | |                                               |                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | BIT Header        | (Signature scanning     |                          |
>> +    | | | (Signature "BIT") |  provides the location  |                          |
>> +    | | +-------------------+  of the BIT table)      |                          |
>> +    | |         | header is                           |                          |
>> +    | |         | followed by a table of tokens       |                          |
>> +    | |         V one of which is for falcon data.    |                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | BIT Tokens        |                         |                          |
>> +    | | |  ______________   |                         |                          |
>> +    | | | | Falcon Data |   |                         |                          |
>> +    | | | | Token (0x70)|---+------------>------------+--+                       |
>> +    | | | +-------------+   |  falcon_data_ptr()      |  |                       |
>> +    | | +-------------------+                         |  V                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    |              (no gap between images)               |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | EFI Image (Type 0x03)                         |  |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | Contains the UEFI GOP driver (Graphics Output)|  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | ROM Header        |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | PCIR Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | NPDE Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | Image data        |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    |              (no gap between images)               |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | First FwSec Image (Type 0xE0)                 |  |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | ROM Header        |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | PCIR Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | NPDE Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | Image data        |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    |              (no gap between images)               |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | Second FwSec Image (Type 0xE0)                |  |                       |
>> +    | +-----------------------------------------------+  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | ROM Header        |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | PCIR Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | NPDE Structure    |                         |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | |                                               |  |                       |
>> +    | | +-------------------+                         |  |                       |
>> +    | | | PMU Lookup Table  | <- falcon_data_offset <----+                       |
>> +    | | | +-------------+   |    pmu_lookup_table     |                          |
>> +    | | | | Entry 0x85  |   |                         |                          |
>> +    | | | | FWSEC_PROD  |   |                         |                          |
>> +    | | | +-------------+   |                         |                          |
>> +    | | +-------------------+                         |                          |
>> +    | |         |                                     |                          |
>> +    | |         | points to                           |                          |
>> +    | |         V                                     |                          |
>> +    | | +-------------------+                         |                          |
>> +    | | | FalconUCodeDescV3 | <- falcon_ucode_offset  |                          |
>> +    | | | (FWSEC Firmware)  |    fwsec_header()       |                          |
>> +    | | +-------------------+                         |                          |
>> +    | |         |   immediately followed  by...       |                          |
>> +    | |         V                                     |                          |
>> +    | | +----------------------------+                |                          |
>> +    | | | Signatures + FWSEC Ucode   |                |                          |
>> +    | | | fwsec_sigs(), fwsec_ucode()|                |                          |
>> +    | | +----------------------------+                |                          |
>> +    | +-----------------------------------------------+                          |
>> +    |                                                                            |
>> +    +----------------------------------------------------------------------------+
>> +
>> +Falcon data Lookup
>> +------------------
>> +A key part of the VBIOS extraction code (vbios.rs) is to find the location of the
>> +Falcon data in the VBIOS which contains the PMU lookup table. This lookup table is
>> +used to find the required Falcon ucode based on an application ID.
>> +
>> +The location of the PMU lookup table is found by scanning the BIT (`BIOS Information Table`_)
>> +tokens for a token with the id `BIT_TOKEN_ID_FALCON_DATA` (0x70) which indicates the
>> +offset of the same from the start of the VBIOS image. Unfortunately, the offset
>> +does not account for the EFI image located between the PciAt and FwSec images.
>> +The `vbios.rs` code compensates for this with appropriate arithmetic.
>> +
>> +.. _`BIOS Information Table`: https://download.nvidia.com/open-gpu-doc/BIOS-Information-Table/1/BIOS-Information-Table.html
> 
> The rest looks good.
> 
> Thanks.
> 



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