Re: [edk2-devel] [PATCH 0/4] OvmfPkg: add virtio serial driver

["Gupta, Pankaj" <pankaj.gupta@amd.com>]

>>> libvirt snippet (add to <devices>):
>>>
>>>       <console type='pty'>
>>>         <target type='virtio' port='0'/>
>>>       </console>
>> Was thinking about the motivation to add the virtio serial device.
>>
>> AFAIU this can provide a console in bios/early boot based on "virtio".
>> Currently we can only get it with emulated PTY device which is slow
>> because of frequent VMEXITS because of ioport write?
> 
> Yes, it has better performance because it wouldn't vmexit for every
> single character.
> 
> Dawback is that it wouldn't work for early logging, the driver loads
> relatively late because it depends on pci and virtio.  So if the
> firmware panics in SEC or PEI you wouldn't see that.
> 
> So for debug logging it isn't the best choice, for efi shell and grub it
> works fine.

Sure.

> 
>> Or is there any other reason (e.g across the ARCH support) to add this
>> support in UEFI ?
> 
> Should work on all architectures, although it needs some platform setup
> code to have the firmware actually bind the firmware console to it (see
> patch #4). >
> Another nice property of a virtio console is that systemd will spawn a
> getty there even if it is not explicitly configured as console device.

Nice.

Thanks,
Pankaj