On Tue, Jan 22, 2019 at 04:23:06PM +0000, David Woodhouse wrote: > On Tue, 2019-01-22 at 16:13 +0000, Ni, Ray wrote: > > David, > > I'd like to re-start the discussion. > > Could you please kindly explain the background/reason of adding CSM > > support in OVMF? > > Maybe knowing the reason can help to make further decisions of > > whether to > > A. keep it outside OvmfPkg > > B. keep it inside OvmfPkg > > C. maybe have a chance to just remove the CSM support after > > revisiting > > The idea was to make it simple to have a single firmware image for > virtual machines which would support both UEFI and Legacy boot for > guests simultaneously.
The idea never really took off though. > In libvirt there has been an alternative approach, where the BIOS image > is switched between OVMF and SeaBIOS according to the configuration of > the guest VM. It's not mandated by libvirt, you can easily create a VM configuration which uses a OVMF build with CSM support. But, yes, it is rarely seen in practice. Microsoft is doing the same btw: hyper-v has gen1 (bios) and gen2 (uefi) guest types. > That's fine for libvirt, but in situations where VM hosting is provided > as a service, it becomes quite painful to manage the 'UEFI' vs. > 'Legacy' flags on guest images and then switch firmware images > accordingly. Seems people try to address this by building cloud images which support both BIOS and UEFI. > A one-size-fits-all BIOS using OVMF+CSM is very much > preferable. Building a one-size-fits-all BIOS is pretty much impossible due to CSM being incompatible with secure boot. cheers, Gerd _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
