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};
13 use std::default::Default;
15 pub fn opts() -> TargetOptions {
16 let mut pre_link_args = LinkArgs::new();
19 LinkerFlavor::Lld(LldFlavor::Link),
21 // Suppress the verbose logo and authorship debugging output, which would needlessly
22 // clog any log files.
23 "/NOLOGO".to_string(),
24 // UEFI is fully compatible to non-executable data pages. Tell the compiler that
25 // non-code sections can be marked as non-executable, including stack pages. In fact,
26 // firmware might enforce this, so we better let the linker know about this, so it
27 // will fail if the compiler ever tries placing code on the stack (e.g., trampoline
28 // constructs and alike).
29 "/NXCOMPAT".to_string(),
30 // There is no runtime for UEFI targets, prevent them from being linked. UEFI targets
31 // must be freestanding.
32 "/nodefaultlib".to_string(),
33 // Non-standard subsystems have no default entry-point in PE+ files. We have to define
34 // one. "efi_main" seems to be a common choice amongst other implementations and the
36 "/entry:efi_main".to_string(),
37 // COFF images have a "Subsystem" field in their header, which defines what kind of
38 // program it is. UEFI has 3 fields reserved, which are EFI_APPLICATION,
39 // EFI_BOOT_SERVICE_DRIVER, and EFI_RUNTIME_DRIVER. We default to EFI_APPLICATION,
40 // which is very likely the most common option. Individual projects can override this
41 // with custom linker flags.
42 // The subsystem-type only has minor effects on the application. It defines the memory
43 // regions the application is loaded into (runtime-drivers need to be put into
44 // reserved areas), as well as whether a return from the entry-point is treated as
45 // exit (default for applications).
46 "/subsystem:efi_application".to_string(),
51 dynamic_linking: false,
53 disable_redzone: true,
54 exe_suffix: ".efi".to_string(),
55 allows_weak_linkage: false,
56 panic_strategy: PanicStrategy::Abort,
59 emit_debug_gdb_scripts: false,
61 linker: Some("rust-lld".to_string()),
62 lld_flavor: LldFlavor::Link,