Xcode 7.3 fails to present the developer with older SDKs. (We filled its SDKs folder with the links to the older SDKs which we need to build).
Needless to say that the older SDKs are needed to build kernel software running at previous OS versions.
Cheers,
Hagen.
I am seeing this message from xcodebuild too, but the build is successful (I'm building 32 bit arch against 10.6 and 64 bit against 10.11 and both succeed).
The "Base SDK" setting does fail to show other installed SDKs, but I have a "User-defined" build setting
SDKROOT_i386 = $(DEVELOPER_SDK_DIR)/MacOSX10.6.sdk
I guess you could do the same setting SDKROOT with no arch