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fix(security): Correct key flow diagram and text around it for AM64X#654

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jsuhaas22 wants to merge 2 commits intoTexasInstruments:masterfrom
jsuhaas22:diagram-bootflow
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fix(security): Correct key flow diagram and text around it for AM64X#654
jsuhaas22 wants to merge 2 commits intoTexasInstruments:masterfrom
jsuhaas22:diagram-bootflow

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The key-flow diagram and the information around it in AM64X's Secure Boot page state that U-Boot uses TI-SCI to authenticate the kernel image. This is no longer the case: U-Boot verifies the kernel image using the fitImage key contained in it without invoking TIFS. Therefore change the docs to reflect this.

New diagram:
K3_KF

@shiva-ti
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@jsuhaas22 let's enable the secure boot doc for am62x platforms in general, for am62l we should also highlight the FIT signing part

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@shiva-ti

@jsuhaas22 let's enable the secure boot doc for am62x platforms in general, for am62l we should also highlight the FIT signing part

For AM62x and AM62P, I have added changes to include the doc. AM62L will require more work, so I will send a separate PR for that in a day or two.

U-boot:

The ti-u-boot source is a project used to create tiboot3.bin, tispl.bin, and u-boot.img. To create tiboot3.bin for AM64x family devices, u-boot builds R5 SPL and
The ti-u-boot source is a project used to create tiboot3.bin, tispl.bin, and u-boot.img. To create tiboot3.bin for Sitara family devices, u-boot builds R5 SPL and
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@shiva-ti shiva-ti Apr 13, 2026

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Better to use K3 instead of Sitara

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@shiva-ti

@jsuhaas22 let's enable the secure boot doc for am62x platforms in general, for am62l we should also highlight the FIT signing part

For AM62x and AM62P, I have added changes to include the doc. AM62L will require more work, so I will send a separate PR for that in a day or two.

@jsuhaas22 sure, please address the relevant comments by the bot, looks fine otherwise.

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@shiva-ti

@jsuhaas22 let's enable the secure boot doc for am62x platforms in general, for am62l we should also highlight the FIT signing part

For AM62x and AM62P, I have added changes to include the doc. AM62L will require more work, so I will send a separate PR for that in a day or two.

@jsuhaas22 sure, please address the relevant comments by the bot, looks fine otherwise.

@shiva-ti Done. There are still some warnings left but those are invalid.

shiva-ti
shiva-ti previously approved these changes Apr 14, 2026
Kernel/DTB/initfamfs. This is accomplished by calling into TIFS via TI-SCI (Texas Instruments System controller Interface). This allows us to use
the same signing/encrypting tools used to authenticate the first-stage image. For more infomation using TI_SCI methods refer to the
`TISCI User Guide <https://software-dl.ti.com/tisci/esd/22_01_02/index.html>`__.
We offer methods for U-Boot's SPL loader to securely verify and encrypt the U-Boot proper. U-Boot calls TIFS through TI-SCI (Texas Instruments System Controller Interface)
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@jsuhaas22 It should be "verify and decrypt the U-Boot proper".
Btw, we don't support the encrypted boot atleast for the U-Boot in the PSDK so it should only be "verify the U-Boot proper".

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The fitImage box shows "u-boot-dtb*.dtb". Is it correct? It should be Kernel DTBs, right?

The key-flow diagram and the information around it in AM64X's Secure Boot page
state that U-Boot uses TI-SCI to authenticate the kernel image. This is no
longer the case: U-Boot verifies the kernel image using the fitImage key
contained in it without invoking TIFS. Therefore change the docs to reflect
this.

Signed-off-by: Suhaas Joshi <s-joshi@ti.com>
@jsuhaas22
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@p-shivhare-ti Addressed your comments.

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Acronyms should follow their definitions, not the other way around. File roles should be prioritized when they can be.

Comment on lines 42 to 43
Secure boot has layers. Some layers are trusted more than others. Secure ROM has the highest trust and REE (Runtime Execution
Environment) non-trustzone user-space applications have the least. If any higher trust code is to be loaded by a lower trust entity, it must be verified
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Suggested change
Secure boot has layers. Some layers are trusted more than others. Secure ROM has the highest trust and REE (Runtime Execution
Environment) non-trustzone user-space applications have the least. If any higher trust code is to be loaded by a lower trust entity, it must be verified
Secure boot has layers. Some layers are trusted more than others. Secure ROM has the highest trust and Runtime Execution
Environment (REE) non-trustzone user-space applications have the least. If any higher trust code is to be loaded by a lower trust entity, it must be verified

Kernel/DTB/initfamfs. This is accomplished by calling into TIFS via TI-SCI (Texas Instruments System controller Interface). This allows us to use
the same signing/encrypting tools used to authenticate the first-stage image. For more infomation using TI_SCI methods refer to the
`TISCI User Guide <https://software-dl.ti.com/tisci/esd/22_01_02/index.html>`__.
We offer methods for U-Boot's SPL loader to securely verify the U-Boot proper. U-Boot calls TIFS through TI-SCI (Texas Instruments System Controller Interface)
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Suggested change
We offer methods for U-Boot's SPL loader to securely verify the U-Boot proper. U-Boot calls TIFS through TI-SCI (Texas Instruments System Controller Interface)
We offer methods for U-Boot's SPL loader to securely verify the U-Boot proper. U-Boot calls TIFS through Texas Instruments System Controller Interface (TI-SCI)


The ti-linux-firmware is a TI repository where all firmware releases are stored. Firmwares for a device family can also be found in the pre-built SDK
under <path-to-tisdk>/board-support/prebuilt-images/am64xx-evm. Binman expects to find the device firmware with the following appended to u-boot build command:
under <path-to-tisdk>/board-support/prebuilt-images/<evm>. Binman expects to find the device firmware with the following appended to u-boot build command:
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Suggested change
under <path-to-tisdk>/board-support/prebuilt-images/<evm>. Binman expects to find the device firmware with the following appended to u-boot build command:
under :file:`<path-to-tisdk>/board-support/prebuilt-images/<evm>`. Binman expects to find the device firmware with the following appended to u-boot build command:

@jsuhaas22 jsuhaas22 force-pushed the diagram-bootflow branch 2 times, most recently from 1df2f56 to b683f64 Compare April 15, 2026 01:58
Currently, the secure boot section is tailored for AM64x. But the same
information is applicable to non-AM64x SoCs, that is AM62x, AM62P. Therefore
generalize the page and add it these other devices' TOCs.

In addition, fix the language in the file to simplify it by changing a few
passive voice statements into active voice, using easier words etc.

Signed-off-by: Suhaas Joshi <s-joshi@ti.com>
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Addressed your comments, @StaticRocket

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