[PATCH v3 16/18] pxe: Refactor sysboot to have one helper

[art]

OK is clear

Reviewed and Tested on -master Mon 18 Oct 2021 04:40:29 PM CST
Reviewed-by: Artem Lapkin <email2tema at gmail.com>
Tested-by:  Artem Lapkin <email2tema at gmail.com>