CPU Speed at MB1 bootloader time?

At MB1 time during the Xavier AGX boot process, what is the CPU speed? I’m looking through the MB1 configuration details and it’s not immediately obvious to me what the speed of the single CPU “boot core” is at that time.

Thank you,


Hi Andy,

What is the purpose of checking this? Also, do you mean the cpu frequency during MB1?

I want to ensure the CPU core “boot-core” is running as fast (or close) as possible (e.g., 2.3 Ghz).

Yes, I mean the frequency of the CPU boot-core. I’m assuming that the speed/frequency during boot (MB1, MB2, CBOOT) does not vary because a more sophisticated scheduler is necessary to really vary the clock frequencies as is supported by the full Linux kernel.

The max validated boot frequency is 1.3G. Beyond this is not validated. So, may result in unwanted errors.

Understood. We may try to increase the frequency when entering CBoot because we noticed that the time-to-transit CBoot is fairly lengthy.

We are trying to optimize the CBoot time down to 1-2 seconds. First, we removed the several seconds of wait-times in CBoot. We have an embedded system booting only from eMMC (ever) so we disabled the code to support all other booting mechanisms. Doing all these changes gets the total boot time down to about 3.4s.

We noticed that eMMC is only achieving 166 MB/s despite being initialized to HS400 mode. And the time to SHA2 authenticate the 34 MB kernel using the Security engine (SE) is very slow at about 0.5s.

Considering the potential value to Nvidia customers for booting faster, I do suggest that a faster CPU frequency for MB1-to-CBoot be investigated for a future JetPack. Otherwise, the CBoot source code has been nicely crafted and simple to change - my compliments to whoever at Nvidia has been maintaining CBoot. Thanks!