rustc_target/spec/targets/
x86_64_unknown_uefi.rs

1// This defines the amd64 target for UEFI systems as described in the UEFI specification. See the
2// uefi-base module for generic UEFI options. On x86_64 systems (mostly called "x64" in the spec)
3// UEFI systems always run in long-mode, have the interrupt-controller pre-configured and force a
4// single-CPU execution.
5// The win64 ABI is used. It differs from the sysv64 ABI, so we must use a windows target with
6// LLVM. "x86_64-unknown-windows" is used to get the minimal subset of windows-specific features.
7
8use rustc_abi::{CanonAbi, X86Call};
9
10use crate::spec::{RustcAbi, Target, TargetMetadata, base};
11
12pub(crate) fn target() -> Target {
13    let mut base = base::uefi_msvc::opts();
14    base.cpu = "x86-64".into();
15    base.plt_by_default = false;
16    base.max_atomic_width = Some(64);
17    base.entry_abi = CanonAbi::X86(X86Call::Win64);
18
19    // We disable MMX and SSE for now, even though UEFI allows using them. Problem is, you have to
20    // enable these CPU features explicitly before their first use, otherwise their instructions
21    // will trigger an exception. Rust does not inject any code that enables AVX/MMX/SSE
22    // instruction sets, so this must be done by the firmware. However, existing firmware is known
23    // to leave these uninitialized, thus triggering exceptions if we make use of them. Which is
24    // why we avoid them and instead use soft-floats. This is also what GRUB and friends did so
25    // far.
26    //
27    // If you initialize FP units yourself, you can override these flags with custom linker
28    // arguments, thus giving you access to full MMX/SSE acceleration.
29    base.features = "-mmx,-sse,+soft-float".into();
30    base.rustc_abi = Some(RustcAbi::X86Softfloat);
31
32    Target {
33        llvm_target: "x86_64-unknown-windows".into(),
34        metadata: TargetMetadata {
35            description: Some("64-bit UEFI".into()),
36            tier: Some(2),
37            host_tools: Some(false),
38            std: None, // ?
39        },
40        pointer_width: 64,
41        data_layout:
42            "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128".into(),
43        arch: "x86_64".into(),
44
45        options: base,
46    }
47}
rustc_target/spec/targets/x86_64_unknown_uefi.rs

rustc_target/spec/targets/
x86_64_unknown_uefi.rs
