What’s your board and BIOS? Syslinux 6.x COM32 Linux loader
goes through the memmap layer syslinux_memmap_find() to place the kernel/initrd. If INT 15h E820 is missing and/or buggy on a 486 BIOS, it can surface as “invalid argument”.
For my 486 distro[see snacklinux.org], I use syslinux 4.07 due to similar issues. I never had any luck with syslinux 6.x, I’d recommend a similar path. It always seems funny to me when I see similar projects, claiming it runs on 486 hardware but rarely do I see people actually doing that, and just fire up qemu instead. Running Linux in a vacuum isn’t realistic, especially when we’re talking old hardware and configuring IRQs manually.
For my 486 distro[see snacklinux.org], I use syslinux 4.07 due to similar issues. I never had any luck with syslinux 6.x, I’d recommend a similar path. It always seems funny to me when I see similar projects, claiming it runs on 486 hardware but rarely do I see people actually doing that, and just fire up qemu instead. Running Linux in a vacuum isn’t realistic, especially when we’re talking old hardware and configuring IRQs manually.