iPxe.kpxe or undionly.kpxe, which is to choose ?

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So, what is the fastest way for booting itself and booting images, is to use ipxe.pxe or undionly.kpxe ?

I built ipxe by myself.
And there is one nasty thing.
If I use ipxe.pxe, booting hans up after Features banner and Ctrl+B request, there is no even net configuration process shown.
If I use undionly.kpxe from the same compiled version, all is good.
And autoboot from shell do not work as well in case of ipxe.pxe.