---
name: "cbfstool"
section: "8"
platform: "linux"
package: "coreboot-utils"
version: "24.12+dfsg-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/cbfstool"
---

# cbfstool(8)

Management utility for CBFS formatted ROM images (coreboot tools)

## NAME

cbfstool - Management utility for CBFS formatted ROM images (coreboot tools)

## SYNOPSIS

```
cbfstool [-h]
cbfstool FILE COMMAND [-v] [PARAMETERS]...
```

## DESCRIPTION

Management utility for CBFS formatted ROM images

## OPTIONS

- **-H** header\_offset

  Do not search for header; use this offset\*

- **-T**

  Output top-aligned memory address

- **-u**

  Accept short data; fill upward/from bottom

- **-d**

  Accept short data; fill downward/from top

- **-F**

  Force action

- **-g**

  Generate position and alignment arguments

- **-U**

  Unprocessed; don't decompress or make ELF

- **-v**

  Provide verbose output (**-v**=*INFO* **-vv**=*DEBUG* output)

- **-h**

  Display this help message

- **--ext-win-base**

  Base of extended decode window in host address space(x86 only)

- **--ext-win-size**

  Size of extended decode window in host address space(x86 only)

### COMMANDS

- *add* \[-r image,regions\] **-f** FILE **-n** NAME **-t** TYPE \[-A hash\]

  \[-c compression\] \[-b base-address \| **-a** alignment\] \[-p padding size\] \[-y\|--xip if TYPE is FSP\] \[-j topswap-size\] (Intel CPUs only) \[--ibb\] \[--ext-win-base win-base **--ext-win-size** win-size\]

  Add a component

  **-j** valid size: 0x10000 0x20000 0x40000 0x80000 0x100000

- *add-payload* \[-r image,regions\] **-f** FILE **-n** NAME \[-A hash\]

  \[-c compression\] \[-b base-address\] (linux specific: \[-C cmdline\] \[-I initrd\])

  Add a payload to the ROM

- *add-stage* \[-r image,regions\] **-f** FILE **-n** NAME \[-A hash\]

  \[-c compression\] \[-b base\] \[-S comma-separated-section(s)-to-ignore\] \[-a alignment\] \[-Q\|--pow2page\] \[-y\|--xip\] \[--ibb\] \[--ext-win-base win-base **--ext-win-size** win-size\]

  Add a stage to the ROM

- *add-flat-binary* \[-r image,regions\] **-f** FILE **-n** NAME

  \[-A hash\] **-l** load-address **-e** entry-point \[-c compression\] \[-b base\]

  Add a 32bit flat mode binary

- *add-int* \[-r image,regions\] **-i** INTEGER **-n** NAME \[-b base\]

  Add a raw 64-bit integer value

- *add-master-header* \[-r image,regions\] \[-j topswap-size\] (Intel CPUs only)

  Add a legacy CBFS master header

- *remove* \[-r image,regions\] **-n** NAME

  Remove a component

- *compact* **-r** image,regions

  Defragment CBFS image.

- *copy* **-r** image,regions **-R** source-region

  Create a copy (duplicate) cbfs instance in fmap

- *create* **-m** ARCH **-s** size \[-b bootblock offset\]

  \[-o CBFS offset\] \[-H header offset\] \[-B bootblock\]

  Create a legacy ROM file with CBFS master header\*

- *create* **-M** flashmap \[-r list,of,regions,containing,cbfses\]

  Create a new-style partitioned firmware image

- *layout* \[-w\]

  List mutable (or, with **-w**, readable) image regions

- *print* \[-r image,regions\] \[-k\]

  Show the contents of the ROM

- *extract* \[-r image,regions\] \[-m ARCH\] **-n** NAME **-f** FILE \[-U\]

  Extracts a file from ROM

- *write* \[-F\] **-r** image,regions **-f** file \[-u \| **-d\]** \[-i int\]

  Write file into same-size \[or larger\] raw region

- *read* \[-r fmap-region\] **-f** file

  Extract raw region contents into binary file

- *truncate* \[-r fmap-region\]

  Truncate CBFS and print new size on stdout

- *expand* \[-r fmap-region\]

  Expand CBFS to span entire region

### OFFSETS

Numbers accompanying **-b**, **-H**, and **-o** switches\* may be provided in two possible formats: if their value is greater than 0x80000000, they are interpreted as a top-aligned x86 memory address; otherwise, they are treated as an offset into flash.

### ARCHITECTURES

arm64, arm, mips, ppc64, power8, riscv, x86, unknown

### TYPES

bootblock, cbfs header, legacy stage, stage, simple elf, fit\_payload, optionrom, bootsplash, raw, vsa, mbi, microcode, intel\_fit, fsp, mrc, cmos\_default, cmos\_layout, spd, mrc\_cache, mma, efi, struct, deleted, null, amdfw

**Note** that these actions and switches are only valid when working with legacy images whose structure is described primarily by a CBFS master header. New-style images, in contrast, exclusively make use of an FMAP to describe their layout: this must minimally contain an 'FMAP' section specifying the location of this FMAP itself and a 'COREBOOT' section describing the primary CBFS. It should also be noted that, when working with such images, the **-F** and **-r** switches default to 'COREBOOT' for convenience, and the **-b** switch becomes relative to the selected CBFS region's lowest address. The one exception to this rule is the top-aligned address, which is always relative to the end of the entire image rather than relative to the local region; this is true for for both input (sufficiently large) and output (**-T**) data.

## AUTHORS

```
coresystems GmbH.
Man page written by Ahmad Khalifa.
```