Paul Brook writes ("Re: [Qemu-devel] [PATCH] CPPFLAGS+= in Makefile.target"):
> In that case you should always provide a definition in config-host.mak.
> Under some circumstances make may inherit initial values from elsewhere.What circumstances ? CPPFLAGS+= overrides (discards) values in the environment as well as ones from the command line. Providing a definition in config-host.mak involves duplicating the value, which can't be right. If there's no other way to do it then there should be a reference to USER_CPPFLAGS or some such but frankly that's a pain and overkill. Ian.
