Daniele,
The logo issue is due to the [Hii-Binary-Package.UEFI_HII] build rule not being supported by XCODE and RVCT those toolchains don’t contain resource compilers for PE/COFF files so they can’t inject HII into PE/COFF images. I submitted patches to fix this a while back and they got stuck and I got bogged down on my day job. This reminds me I need to get those patches moving again.
Due to the issue above the XCODE build skips some drivers/apps in OVMF [1] but I don’t think that is your issue?
I don’t think it is likely that your graphics issue is related to HII resources. Most of the times when I track down the “it does not work with clang (Xcode uses clang)” it ends up being the clang compiler optimizing away undefined behavior that the other compilers ignored. I’m not sure if there is a another clang toolchain you could try? That would be helpful to know if it is likely an undefined behavior difference.
Unfortunately the graphics issue is going to be hard to track down if we can’t reproduce it locally.
[1] Easiest way to find them is:
/Volumes/Case/edk2-github(master)>git grep '$(TOOL_CHAIN_TAG) == "XCODE5"'
OvmfPkg/OvmfPkgIa32.dsc:252:!if $(TOOL_CHAIN_TAG) == "XCODE5"
OvmfPkg/OvmfPkgIa32X64.dsc:256:!if $(TOOL_CHAIN_TAG) == "XCODE5"
OvmfPkg/OvmfPkgX64.dsc:256:!if $(TOOL_CHAIN_TAG) == "XCODE5"
OvmfPkg/OvmfXen.dsc:233:!if $(TOOL_CHAIN_TAG) == "XCODE5"
UefiCpuPkg/UefiCpuPkg.dsc:63:!if $(TOOL_CHAIN_TAG) == "XCODE5"
Thanks,
Andrew Fish