L4T r32.5.0 t210 cboot cannot access LNX on sd

I do Android development on many Tegra devices, including the Jetsons. As the cboot source for t210 has not been released, even though it’s been promised for almost 2 years now, I have to make due with the prebuilt l4t copy for p3448. As of l4t r32.4.4, Cboot on the nano 2gb/4gb dev modules would read LNX from the sd as expected. As of l4t r32.5.0, Cboot will only read LNX from qspi. Nvtboot will also only read many other boot partitions from qspi and not the sd. While a small u-boot image fits into the small space allocated to LNX on qspi, a Linux kernel as needed to boot android cannot fit. Please advise if cboot source will be released soon, so such options can be configured as needed, or if support for reading boot partitions from the sd can be re-enabled on official l4t builds.

Hi Steel01,

Sorry that there is still no plan to release cboot src for t210.

Could you give more detail about why this does not work after we move the uboot to qspi?

The android boot sequence does not involve u-boot. The boot image is created with the kernel and optionally a ramdisk and flashed to LNX.


It is possible to move the production to emmc based module?
The sdcard module is not targeting to be made as a product. It can only be used on nv devkit.

If you move to emmc based module, then all the partitions will be on emmc so it may have larger size.

The main target for my work is hobbiests. And the devkits are the more used devices there. Yes, the emmc based devices such as the tx1 devkit, the tx2 devkit, and agx xavier work as expected. The nx devkit also still works as expected, loading LNX from the sd. However for t186 and t194 targets, cboot source is available, allowing proper android support in the bootloader, or re-enabling sd support if necessary. My intent is to support all available Tegra hardware, t210+.


Nano devkit’s QSPI is 4MB. That’s just too small to support any kind of kernel, unless you are using an extremely stripped-down Android kernel. So there’s no way to put a kernel into LNX on Nano SKU0.

If you are willing to do the work, you can modify U-Boot (it is open source) and make it load your Android kernel from SD instead of our L4T kernel.

I can boot android from u-boot, yes. And have done so on the Jetson Nano and a couple of the SHIELD devices. But it is preferable to have less moving parts.

Cboot as released with L4T r32.4.4 and earlier supported the LNX partition on the sd card. This support was removed with the release of L4T r32.5.0, which for my use case is a regression. This has caused me to pin the t210 Nano bootstack at r32.4.4 while updating t186 and t194 to r32.5.0. The Xavier NX still supports loading kernel/kernel_b from the sd card on r32.5.0. Is the plan going forward to remove any support for non-qspi boot on all nano/nx dev modules and only have kernel/userspace support for larger media?