1 // This defines a base target-configuration for native UEFI systems. The UEFI specification has
2 // quite detailed sections on the ABI of all the supported target architectures. In almost all
3 // cases it simply follows what Microsoft Windows does. Hence, whenever in doubt, see the MSDN
5 // UEFI uses COFF/PE32+ format for binaries. All binaries must be statically linked. No dynamic
6 // linker is supported. As native to COFF, binaries are position-dependent, but will be relocated
7 // by the loader if the pre-chosen memory location is already in use.
8 // UEFI forbids running code on anything but the boot-CPU. No interrupts are allowed other than
9 // the timer-interrupt. Device-drivers are required to use polling-based models. Furthermore, all
10 // code runs in the same environment, no process separation is supported.
12 use crate::spec::{LinkArgs, LinkerFlavor, LldFlavor, PanicStrategy, TargetOptions};
14 pub fn opts() -> TargetOptions {
15 let pre_link_args_msvc = vec![
16 // Suppress the verbose logo and authorship debugging output, which would needlessly
17 // clog any log files.
18 "/NOLOGO".to_string(),
19 // UEFI is fully compatible to non-executable data pages. Tell the compiler that
20 // non-code sections can be marked as non-executable, including stack pages. In fact,
21 // firmware might enforce this, so we better let the linker know about this, so it
22 // will fail if the compiler ever tries placing code on the stack (e.g., trampoline
23 // constructs and alike).
24 "/NXCOMPAT".to_string(),
25 // Non-standard subsystems have no default entry-point in PE+ files. We have to define
26 // one. "efi_main" seems to be a common choice amongst other implementations and the
28 "/entry:efi_main".to_string(),
29 // COFF images have a "Subsystem" field in their header, which defines what kind of
30 // program it is. UEFI has 3 fields reserved, which are EFI_APPLICATION,
31 // EFI_BOOT_SERVICE_DRIVER, and EFI_RUNTIME_DRIVER. We default to EFI_APPLICATION,
32 // which is very likely the most common option. Individual projects can override this
33 // with custom linker flags.
34 // The subsystem-type only has minor effects on the application. It defines the memory
35 // regions the application is loaded into (runtime-drivers need to be put into
36 // reserved areas), as well as whether a return from the entry-point is treated as
37 // exit (default for applications).
38 "/subsystem:efi_application".to_string(),
40 let mut pre_link_args = LinkArgs::new();
41 pre_link_args.insert(LinkerFlavor::Msvc, pre_link_args_msvc.clone());
42 pre_link_args.insert(LinkerFlavor::Lld(LldFlavor::Link), pre_link_args_msvc);
45 dynamic_linking: false,
47 disable_redzone: true,
48 exe_suffix: ".efi".to_string(),
49 allows_weak_linkage: false,
50 panic_strategy: PanicStrategy::Abort,
53 emit_debug_gdb_scripts: false,
55 linker: Some("rust-lld".to_string()),
56 lld_flavor: LldFlavor::Link,