[U-Boot] handling of NAND blocks which go bad

I have a question about how u-boot handles NAND blocks going bad over time, for example when uncorrectable ECC errors or erase failures are encountered for blocks which are not already in the Bad Block Table. I know that u-boot properly skips already known bad blocks, but I can't seem to find where new bad blocks are recorded in the BBT. Can anyone point me in the right direction? Or confirm that this is not supported in u-boot? I am using a BSP from Freescale on a custom mx25 board, but I cannot find this handling in the latest u-boot git either.

TIA