Hi,

gnu-efi can be cross built for arm architectures. Thank you for taking
care of that. Building it for x86 architectures does not work and the
immediate issue is the reliance on gcc-multilib. The support for
multilib in cross toolchains is near absent, so only real solution I can
offer here is not using multilib. The alternative to multilib is using a
cross toolchain and that happens to just work even in native builds. In
effect, a multilib build kinda is a crippled cross build and we can
expand it into a regular cross build without much effort.

I've turned this idea into a patch that you find attached. It
significantly changes debian/rules as I also encountered build/host
confusion. You already noticed that upstream uses these terms with a
meaning that differs from Debian's and still some occasions were using
it wrongly. I performed the following test builds with success:
 * native amd64
 * amd64 -> i386 cross build
 * amd64 -> arm64 cross build

The first two exercise previously used multilib and now work without.

Hope you find the proposed changes acceptable. Let me know if you have
any questions.

Helmut