AM62P-Q1: Boot process of M4F image loading

Tim Wang

Part Number: AM62P-Q1
Other Parts Discussed in Thread: AM62P

Hi, TI experts,

Q1:

We found a description in spruj83c.pdf about the Boot process, focus on M4F image loading and starting, there is a conflict point:

in chapter "5.2.2 M4 ROM Description", it mentioned, M4 ROM will loading M4 firmware
but in "Figure 5-4. External Bootloader Tasks", it said "SBL Loads M4 firmware", I think this SBL will be belong to R5F core:

which one is correct?

We know during boot process, the M4F ROM or named Secure ROM, will handle the integrity check (X509 verification) of images, which is requested by R5F public ROM.

Q2:

If the Secure Boot enabled, whether the operation of "R5F image" and "M4F image (TIFS)" integrity check with X.509 verification are mandatory implemented by TI Public/Secure ROM?

If yes, What about other images, e.g. A53 cores' image?

Thanks very much!

6 months ago

0 Hong Guan64 6 months ago

TI__Guru* 79820 points

Hi Pengfei,

A new flow - the combined boot flow was introduced in AM62P ROM. Refer to <5.7.5 Extended Boot Info Extension> in AM62P TRM for details.
"The ROM supports a combined boot image boot flow. In this flow, a boot binary blob has both Secondary bootloader (SBL) and System Firmware (SYS-FW) embedded in the boot image with a single X509 certificate."

<5.2.2 M4 ROM Description> is correct, where SYS-FW is loaded by ROM.
<Figure 5-4. External Bootloader Tasks> needs to be updated on the combined boot flow.

Best,
-Hong

0 Tim Wang 6 months ago in reply to Hong Guan64

Prodigy 170 points

Hi Hong,

Thanks for reply.

According to this process, the R5F SBL will be loaded by R5F Public ROM or M4F Secure ROM? from below sequence from Figure 5-3. Boot Process:

R5F start Primary Boot and will get the image from external media, I think this image included R5F SBL. am I correct?

But from <5.7.5 Extended Boot Info Extension>, it mentioned the R5F SBL and TIFS will be combined and verified with a single X.509 certificate. does it mean the SBL will be loaded also by Secure ROM?

0 Hong Guan64 6 months ago in reply to Tim Wang

TI__Guru* 79820 points

Hi Pengfei,

Here is the secure boot flow from AM62x Security Overview slide accessible from
https://dr-download.ti.com/authenticated/software-development/application-software-framework/MD-W5I8h4voaD/09.01.00.05/AM62x_Security_Overview_1Q23_v1.pdf?

Hopefully it helps clarifying your questions.

Best,
-Hong

0 Tim Wang 6 months ago in reply to Hong Guan64

Prodigy 170 points

In this Flow, only mention Public ROM send request Secure ROM to integrity check the R5 SBL, but don't have R5 SBL loading operation. Whether this loading operation also handled by Public ROM?

+1 Hong Guan64 6 months ago in reply to Tim Wang

TI__Guru* 79820 points

The first user bootloader "tiboot3.bin" reading from external boot media is handled by Public-ROM, and the certificate authentication is by Secure-ROM.
Best,
-Hong

0 Tim Wang 6 months ago in reply to Hong Guan64

Prodigy 170 points

Ok, Clear for this point.

There is another point:

In TRM "Figure 5.3 Boot Process", it mentioned: "M4 Sends Message to R5 with Boot Mode Info", does it mean, the Boot Mode Pin value will be read by Secure M4F ROM and send the value to Public ROM?

The other sentence from same chapter, it said "R5 will check the boot made pins..."

A little confused for us, finally which ROM will read the Bode Mode Pins? and after read, whether shared to other ROM?

+1 Hong Guan64 6 months ago in reply to Tim Wang

TI__Guru* 79820 points

<Figure 5-3. Boot Process> is correct that the boot-mode pin status is read by secure-rom, & passed to public-rom via the boot info message.
Best,
-Hong

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AM62P-Q1: Boot process of M4F image loading