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// This defines the amd64 target for UEFI systems as described in the UEFI specification. See the
// uefi-base module for generic UEFI options. On x86_64 systems (mostly called "x64" in the spec)
// UEFI systems always run in long-mode, have the interrupt-controller pre-configured and force a
// single-CPU execution.
// The win64 ABI is used. It differs from the sysv64 ABI, so we must use a windows target with
// LLVM. "x86_64-unknown-windows" is used to get the minimal subset of windows-specific features.
use crate::spec::Target;
pub fn target() -> Target {
let mut base = super::uefi_msvc_base::opts();
base.cpu = "x86-64".into();
base.max_atomic_width = Some(64);
// We disable MMX and SSE for now, even though UEFI allows using them. Problem is, you have to
// enable these CPU features explicitly before their first use, otherwise their instructions
// will trigger an exception. Rust does not inject any code that enables AVX/MMX/SSE
// instruction sets, so this must be done by the firmware. However, existing firmware is known
// to leave these uninitialized, thus triggering exceptions if we make use of them. Which is
// why we avoid them and instead use soft-floats. This is also what GRUB and friends did so
// far.
//
// If you initialize FP units yourself, you can override these flags with custom linker
// arguments, thus giving you access to full MMX/SSE acceleration.
base.features = "-mmx,-sse,+soft-float".into();
Target {
llvm_target: "x86_64-unknown-windows".into(),
pointer_width: 64,
data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
.into(),
arch: "x86_64".into(),
options: base,
}
}
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