As an obstacle for upstreaming some particularly older NVIDIA Tegra devices (namely those running Android) is that they have GPT entry at the wrong location or lacking at all for boot support. That missing or botched GPT support is because those older devices make use of a NVIDIA proprietary/closed-source table format. As such, support for this proprietary NVIDIA Tegra Partition Table is being worked on for the Linux kernel to provide better upstream kernel support on these consumer devices.
NVIDIA Tegra devices primarily rely on a special partition table format for their internal storage while some also support traditional GPT partitions.
[Source: Phoronix]
