rEFInd has this feature: It can load a bios bootloader despite running in uefi mode.
I consulted grub documentation, and it doesn't mention whether grub supports this feature. So it seems grub lack this feature. If grub officially doesn't provide this functionality, how can I implement it manually? Is it possible to do some coding and add a new module to grub-efi so as to chainload bios bootloaders?
Loading a bios bootloader when running in efi mode is very useful: In some cases, people has a major harddisk with os installed in efi mode, besides he has a secondary mobile disk with a rescue os installed in bios mode. If he uses grub, everytime he switches beetween the two os'es in the two disks, he has to go to the motherboard settings to change the boot mode. It is pretty inconvenient. So I hope grub will support it officially in the feature releases.
BTW, when will the stable version of grub 2.02 release? Do you have any release plan (i.e. how often is grub stable version released)?