can't boot with legacy

[The Hero of Orlais]

so i just installed linux on my laptop, but to have the dual boot i assume i need to boot from legacy ? but the thing is, my laptop keeps booting through EUFI, i have disabled secure boot and enable CSM, i have an Aptio BIOS 2016

 

[kerberos_20]

uefi can go with dual boot
if u installed one OS as legacy and the other as UEFI, then ure out of luck