In Arch Linux
mkinitcpio -p linux
shows
Possibly missing firmware for module: aic94xx
Possibly missing firmware for module: wd719x
git clone https://aur.archlinux.org/aic94xx-firmware.git
cd aic94xx-firmware
makepkg -sri
git clone https://aur.archlinux.org/wd719x-firmware.git
cd wd719x-firmware
makepkg -sri
and then mkinitcpio -p linux
again.
Warnings aren't simply harmless, though, and they shouldn't be ignored (otherwise there's no point in printing them in the first place!). They are used when there may be a problem. For example, if you did have one of the Disk Controllers in question, it can be problematic if you don't have the proper drivers.
There may be thousands of drivers you don't need, and it would be pointless to warn about every one of them - so why does it warn about these two in particular? If we can fix it and prevent the unnecessary warning, users will no longer have to go searching online to understand the warning and determine if it's a problem.
If there's a solid reason why it cannot be fixed for these two drivers in particular, then we can either leave it as is, add to the warning to identify the hardware that the drivers are for, or maybe make a web page that lists drivers and their corresponding hardware.