From u-boot, load/boot kernel via tftp, using SD for remaining (debian) OS

Hi All,

On the VF2 (1.3b) I have been able to boot, using u-boot, debian via SD card (mmc) and via tftp over the local network. I’m looking to boot the kernel over tftp and then have the OS file tree mounted from SD. I see the pattern in the u-boot env and I’m looking to add env vers for tftpb_boot option,

But, the instructions on booting from tftp use bootm options that don’t seem to be in the u-boot doc’s. Does anyone know what the bootm commands with start and loados args do?
Are they setting internal address variables in u-boot?

   bootm start ${loadaddr};
   bootm loados ${loadaddr};
   run chipa_set_linux;
   run cpu_vol_set;
   booti ${kernel_addr_r} ${ramdisk_addr_r}:${filesize} ${fdt_addr_r};

I’m finding stuff going through the u-boot sources in the VF2 github repo.