How does EDK2 detect virtio-blk-pci device as a boot device

[Xiaohe Yang <xh_young@163.com>]

Hello, I am using EDK2  OvmfPkgX64 at commit 37568365, and have a 
problem. The following is the detail.


The Image disk that I use has EFI system partition, and is configured as 
a virtio-blk-pci device. Bootorder file-entry is not added in fw_cfg 
device. The log of EDK2 shows that

(1)  VirtioBlkDxe.efi is successfully loaded at DXE stage. 
BootScriptExecutorDxe drivers "was discovered but not loaded".

(2) PCI enumeration has finished at the start of BDS stage, 
virtio-blk-pci device is discovered. And one Option Rom's address is 0/0.

(3) Before entering Shell, log shows "map: No mapping found".

(4) After entering Shell, I choose “Boot From File”, the virtio-blk-pci 
device is not displayed.


So I wonder what are the requirements for UEFI to detect the 
virtio-blk-pci device as a boot device, except having EFI system partition?


Thanks,

Xiaohe.