R32.1 Cboot Source

CBoot source for the tx2 was released with r28.2.1 and for the agx with 31.1. Will cboot source be released with 32.1? I do Android work with Tegra devices and need an Android build of cboot for the nano, the tx2, and eventually the agx. The best way to facilitate that would be to build from source.

Hi Steel01, since Jetson Nano is based on TX1 SoC (which has been using U-boot), we are still developing the C-boot sources for the Nano.

I’ve seen this answer a few times around here (also on the tx1 board a couple times over the last several months), but doesn’t add up with what I see elsewhere. The more recent l4t t210 packages flash cboot to EBT, which then chain loads to u-boot. Upstream t210 u-boot support has pending changes from nvidia engineers to chainload from cboot instead of doing initialization itself. So, cboot is very much a part of the t210 boot chain, even for the l4t u-boot path. Will that never be released?

Also, can any comment be made about the r32 cboot source for t186 and t194? Those platforms have had source in previous l4t versions, but it wasn’t released with the rest of the bsp sources for r32.

Hey, Steel01. I’m responsible for the previous CBoot source releases (T18x on R28 and T19x on R31).

I’m working on updating both T18x and T19x source for R32.x (the bootloader code has undergone some re-org, so there’s a bit of work to do to archive it and make it build outside of our build environment). I’ll have that ready for release in time for the next R32 release, if not before.

As to T210 (Nano and TX1) CBoot, that source base is a bit different from T18x/T19x CBoot, and takes a bit more work to collect, archive and rebuild. I’ll be working on that, too, and again, will have it ready for the next R32.x release, if not before.

Hope that answers your questions!


Yes, that’s enough for me, looking forward to the release. Thank you very much.

Hi Tom. Great to hear that T210 cboot will finally be released. I know a lot of people have been clamoring for that for a while. Also I was wondering if T186/T194 cboot will have a functional AVB2 system. I know R31.1 had some very preliminary workings of it, so I assumed you guys were working on it internally already.


Sorry, Rashed. I’m not working directly on AVB (I assume that’s Android Verified Boot 2.0?). I’ll have to leave that to the bootloader team to answer. I’ll forward the question to them.

Yeah it’s Android Verified Boot 2.0, and thanks for forwarding it!


Can you share any inside info on multiboot possibility in the latest cboot code? Booting different kernels (even if it supports rootfs only) would be very helpful and long sought functionality in cboot.



The BL team is working on adding full support for the extlinux file a la U-Boot to T19x CBoot (syslinux spec). When that’s complete, you should be able to add entries to extlinux.conf to allow selection of multiple kernels at boot time, just like on TX1/TX2 U-Boot.



Thanks, Tom. Looking forward to seeing its release.


Hi twarren,

could you please update us with the release date of R32.x cboot source for T18x and T19x?
If not coming sooner then the new L4T release, could you please tell us expected date for the new L4T release?


T19x CBoot source should be available with the R32.2 release that’s imminent - I don’t control the public release flow, so I can’t give an exact date, but I’ve been told it’s going to land in the next day or so.

T18x CBoot source is still being reviewed, and may come out as a stand-alone release tarball, or it may come out with R32.3 later in the year.

do we have the CBoot source on R32.1?

AFAIK, we released both T18x and T19x CBoot source in R32.1. We have released the latest T19x CBoot source in R32.2, as of yesterday.


Any word on the T210 source? (For the Nano in particular.) Back in March you indicated that you thought that it would be released in the next R32.x (which I took to be R32.2). Looks like it didn’t make that cut. Do you think it might be released as part of R32.3?


T210 CBoot source is slated for the R32.3 release. It got held up and didn’t make the R32.2 release during review. It’s something I’m monitoring closely, and will push on each week to make sure it makes the next release.


On 7/10 #14:
“T18x CBoot source is still being reviewed, and may come out as a stand-alone release tarball, or it may come out with R32.3 later in the year.”
On 7/19 #15:
“AFAIK, we released both T18x and T19x CBoot source in R32.1. We have released the latest T19x CBoot source in R32.2, as of yesterday.”
Is the cboot source available for 32.1 or not? Where would I find it? Is it available for 32.2? I need to reserve memory in the device tree for the TX2 and from this discussion and others it appears that I will not be able to do so without the cboot sources.

If the cboot source cannot be released soon
Can you provide the memory map of Jetson Nano initialized by cboot?

Hi twarren,

could you please point me where is the latest T19x CBoot source for R32.2. I can’t find it in the download center.