rustc_target/spec/targets/
x86_64_unknown_uefi.rs

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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 crate::callconv::Conv;
9use crate::spec::{RustcAbi, Target, base};
10
11pub(crate) fn target() -> Target {
12    let mut base = base::uefi_msvc::opts();
13    base.cpu = "x86-64".into();
14    base.plt_by_default = false;
15    base.max_atomic_width = Some(64);
16    base.entry_abi = Conv::X86_64Win64;
17
18    // We disable MMX and SSE for now, even though UEFI allows using them. Problem is, you have to
19    // enable these CPU features explicitly before their first use, otherwise their instructions
20    // will trigger an exception. Rust does not inject any code that enables AVX/MMX/SSE
21    // instruction sets, so this must be done by the firmware. However, existing firmware is known
22    // to leave these uninitialized, thus triggering exceptions if we make use of them. Which is
23    // why we avoid them and instead use soft-floats. This is also what GRUB and friends did so
24    // far.
25    //
26    // If you initialize FP units yourself, you can override these flags with custom linker
27    // arguments, thus giving you access to full MMX/SSE acceleration.
28    base.features = "-mmx,-sse,+soft-float".into();
29    base.rustc_abi = Some(RustcAbi::X86Softfloat);
30
31    Target {
32        llvm_target: "x86_64-unknown-windows".into(),
33        metadata: crate::spec::TargetMetadata {
34            description: Some("64-bit UEFI".into()),
35            tier: Some(2),
36            host_tools: Some(false),
37            std: None, // ?
38        },
39        pointer_width: 64,
40        data_layout:
41            "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128".into(),
42        arch: "x86_64".into(),
43
44        options: base,
45    }
46}
rustc_target/spec/targets/x86_64_unknown_uefi.rs

rustc_target/spec/targets/
x86_64_unknown_uefi.rs
