[U-Boot] U-boot bootcmd

[Boris Borisov]

Hello everybody !

I got recently one of Xburst based mini laptops ( Skytex SX E700)
running version of Linux that I don't like. No support anymore so no
info about how to start upgrade process or to boot from SD/USB. Info
for similar laptops does not work. U-boot shell shows that I have 3
boot variables bootcmd, bootcmd_sd and bootcmd_sd_nerase. How I can
find out what key combination is assigned to branch the normal boot
process in other way. How you assign key combination or other event
for this purpose in U-boot.

Thank you

P.S. I spend about an hour today reading the U-boot manual but no success ....