How to boot alternative kernel image with u-boot?

[zhouer]

Hi,
I'm currently using longsleep's u-boot and kernel image, which work great.
I'm also trying to build some experimental kernel images, however it doesn't always work.
It's quite a troublesome process to remove the sd card, mount on another machine, recover kernel image, put the sd card back, and boot again.
Is it possible to select alternative kernel image from u-boot without remove the sd card?

[longsleep]

See http://linux-sunxi.org/FEL/USBBoot

[zhouer]

See http://linux-sunxi.org/FEL/USBBoot

Fantastic! Thank you so much!

[ssvb]

See http://linux-sunxi.org/FEL/USBBoot

But this does not work with boot0 well, right? First we need to get the SPL support for Allwinner A64 in U-Boot.