Booting kernels older than v5.7

Hi, I'm on the latest TW. I'm trying to bisect for https://bugzilla.suse.com/show_bug.cgi?id=1178474 but I cannot get any kernel older than v5.7 to boot. I do the usual kernel build + modules_install + install. After GRUB, the message says "Loading kernel", then "Loading ramdisk". Then the system stops booting without further messages. Did anything related change around v5.7? Maybe the ramdisk format/compression? Best regards Thomas -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer