[libc] init uefi #131246

RossComputerGuy · 2025-03-14T00:34:51Z

Initial UEFI OS target support after the headers. This just defines enough that stuff might try and compile. Test with:

$ cmake -S llvm -B build -G Ninja -DLLVM_RUNTIME_TARGETS=x86_64-unknown-uefi-llvm -DRUNTIMES_x86_64-unknown-uefi-llvm_LLVM_ENABLE_RUNTIMES=libc -DRUNTIMES_x86_64-unknown-uefi-llvm_LLVM_LIBC_FULL_BUILD=true -DCMAKE_C_COMPILER_WORKS=true -DCMAKE_CXX_COMPILER_WORKS=true -DLLVM_ENABLE_PROJECTS="clang;lld" -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_LIBCXX=true -DLLVM_HOST_TRIPLE=aarch64-unknown-linux-gnu -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-unknown-uefi-llvm -DCMAKE_INSTALL_LIBDIR=build/target/lib
$ ninja -C build

llvmbot · 2025-03-14T00:35:31Z

@llvm/pr-subscribers-libc

Author: Tristan Ross (RossComputerGuy)

Changes

Initial UEFI OS target support after the headers. This just defines enough that stuff might try and compile. Test with:

$ cmake -S llvm -B build -G Ninja -DLLVM_RUNTIME_TARGETS=x86_64-unknown-uefi-llvm -DRUNTIMES_x86_64-unknown-uefi-llvm_LLVM_ENABLE_RUNTIMES=libc -DRUNTIMES_x86_64-unknown-uefi-llvm_LLVM_LIBC_FULL_BUILD=true -DCMAKE_C_COMPILER_WORKS=true -DCMAKE_CXX_COMPILER_WORKS=true -DLLVM_ENABLE_PROJECTS="clang;lld" -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_LIBCXX=true -DLLVM_HOST_TRIPLE=aarch64-unknown-linux-gnu -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-unknown-uefi-llvm -DCMAKE_INSTALL_LIBDIR=build/target/lib
$ ninja -C build

Full diff: https://github.com/llvm/llvm-project/pull/131246.diff

11 Files Affected:

(modified) libc/cmake/modules/LLVMLibCArchitectures.cmake (+2)
(added) libc/config/uefi/config.json (+7)
(added) libc/config/uefi/entrypoints.txt (+11)
(added) libc/config/uefi/headers.txt (+4)
(modified) libc/include/Uefi.yaml (+2-1)
(modified) libc/src/__support/OSUtil/io.h (+2)
(added) libc/src/__support/OSUtil/uefi/CMakeLists.txt (+11)
(added) libc/src/__support/OSUtil/uefi/exit.cpp (+23)
(added) libc/src/__support/OSUtil/uefi/io.cpp (+36)
(added) libc/src/__support/OSUtil/uefi/io.h (+25)
(modified) libc/utils/hdrgen/hdrgen/header.py (+1)

diff --git a/libc/cmake/modules/LLVMLibCArchitectures.cmake b/libc/cmake/modules/LLVMLibCArchitectures.cmake
index b94534bb00980..62f3a2e3bdb59 100644
--- a/libc/cmake/modules/LLVMLibCArchitectures.cmake
+++ b/libc/cmake/modules/LLVMLibCArchitectures.cmake
@@ -191,6 +191,8 @@ elseif(LIBC_TARGET_OS STREQUAL "windows")
   set(LIBC_TARGET_OS_IS_WINDOWS TRUE)
 elseif(LIBC_TARGET_OS STREQUAL "gpu")
   set(LIBC_TARGET_OS_IS_GPU TRUE)
+elseif(LIBC_TARGET_OS STREQUAL "uefi")
+  set(LIBC_TARGET_OS_IS_UEFI TRUE)
 else()
   message(FATAL_ERROR
           "Unsupported libc target operating system ${LIBC_TARGET_OS}")
diff --git a/libc/config/uefi/config.json b/libc/config/uefi/config.json
new file mode 100644
index 0000000000000..51aa8fecf8b30
--- /dev/null
+++ b/libc/config/uefi/config.json
@@ -0,0 +1,7 @@
+{
+  "errno": {
+    "LIBC_CONF_ERRNO_MODE": {
+      "value": "LIBC_ERRNO_MODE_SHARED"
+    }
+  }
+}
diff --git a/libc/config/uefi/entrypoints.txt b/libc/config/uefi/entrypoints.txt
new file mode 100644
index 0000000000000..2e11c534a4f3b
--- /dev/null
+++ b/libc/config/uefi/entrypoints.txt
@@ -0,0 +1,11 @@
+set(TARGET_LIBC_ENTRYPOINTS
+    # errno.h entrypoints
+    libc.src.errno.errno
+)
+
+set(TARGET_LIBM_ENTRYPOINTS)
+
+set(TARGET_LLVMLIBC_ENTRYPOINTS
+  ${TARGET_LIBC_ENTRYPOINTS}
+  ${TARGET_LIBM_ENTRYPOINTS}
+)
diff --git a/libc/config/uefi/headers.txt b/libc/config/uefi/headers.txt
new file mode 100644
index 0000000000000..a8e7b5bc5e37b
--- /dev/null
+++ b/libc/config/uefi/headers.txt
@@ -0,0 +1,4 @@
+set(TARGET_PUBLIC_HEADERS
+    libc.include.errno
+    libc.include.uefi
+)
diff --git a/libc/include/Uefi.yaml b/libc/include/Uefi.yaml
index 28582eb2524b1..9f38ff3f4a497 100644
--- a/libc/include/Uefi.yaml
+++ b/libc/include/Uefi.yaml
@@ -1,5 +1,6 @@
 header: Uefi.h
-standards: UEFI
+standards:
+  - uefi
 macros: []
 types:
   - type_name: EFI_BOOT_SERVICES
diff --git a/libc/src/__support/OSUtil/io.h b/libc/src/__support/OSUtil/io.h
index 80119da77fc02..66af31f3cc8c6 100644
--- a/libc/src/__support/OSUtil/io.h
+++ b/libc/src/__support/OSUtil/io.h
@@ -24,6 +24,8 @@
 #elif defined(__ELF__)
 // TODO: Ideally we would have LIBC_TARGET_OS_IS_BAREMETAL.
 #include "baremetal/io.h"
+#elif defined(__UEFI__)
+#include "uefi/io.h"
 #endif
 
 #endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_IO_H
diff --git a/libc/src/__support/OSUtil/uefi/CMakeLists.txt b/libc/src/__support/OSUtil/uefi/CMakeLists.txt
new file mode 100644
index 0000000000000..79ec8ab602456
--- /dev/null
+++ b/libc/src/__support/OSUtil/uefi/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_object_library(
+  uefi_util
+  SRCS
+    io.cpp
+    exit.cpp
+  HDRS
+    io.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.CPP.string_view
+)
diff --git a/libc/src/__support/OSUtil/uefi/exit.cpp b/libc/src/__support/OSUtil/uefi/exit.cpp
new file mode 100644
index 0000000000000..96bf818ad304a
--- /dev/null
+++ b/libc/src/__support/OSUtil/uefi/exit.cpp
@@ -0,0 +1,23 @@
+//===-------- UEFI implementation of an exit function ------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===-----------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/exit.h"
+#include "src/__support/macros/config.h"
+#include "include/llvm-libc-macros/stdlib-macros.h"
+#include "include/Uefi.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
+
+[[noreturn]] void exit(int status) {
+  efi_system_table->BootServices->Exit(efi_image_handle, status, 0, NULL);
+  __builtin_unreachable();
+}
+
+} // namespace internal
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/uefi/io.cpp b/libc/src/__support/OSUtil/uefi/io.cpp
new file mode 100644
index 0000000000000..756c5aaf8f452
--- /dev/null
+++ b/libc/src/__support/OSUtil/uefi/io.cpp
@@ -0,0 +1,36 @@
+//===---------- UEFI implementation of IO utils ------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===-----------------------------------------------------------------===//
+
+#include "io.h"
+
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+ssize_t read_from_stdin(char *buf, size_t size) { return 0; }
+
+void write_to_stdout(cpp::string_view msg) {
+  // TODO: use mbstowcs once implemented
+  for (size_t i = 0; i < msg.size(); i++) {
+    char16_t e[2] = {msg[i], 0};
+    efi_system_table->ConOut->OutputString(
+        efi_system_table->ConOut, reinterpret_cast<const char16_t *>(&e));
+  }
+}
+
+void write_to_stderr(cpp::string_view msg) {
+  // TODO: use mbstowcs once implemented
+  for (size_t i = 0; i < msg.size(); i++) {
+    char16_t e[2] = {msg[i], 0};
+    efi_system_table->StdErr->OutputString(
+        efi_system_table->StdErr, reinterpret_cast<const char16_t *>(&e));
+  }
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/uefi/io.h b/libc/src/__support/OSUtil/uefi/io.h
new file mode 100644
index 0000000000000..088ae09b8c602
--- /dev/null
+++ b/libc/src/__support/OSUtil/uefi/io.h
@@ -0,0 +1,25 @@
+//===---------- UEFI implementation of IO utils ------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===-----------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_UEFI_IO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_UEFI_IO_H
+
+#include "include/llvm-libc-types/size_t.h"
+#include "include/llvm-libc-types/ssize_t.h"
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+ssize_t read_from_stdin(char *buf, size_t size);
+void write_to_stderr(cpp::string_view msg);
+void write_to_stdout(cpp::string_view msg);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_UEFI_IO_H
diff --git a/libc/utils/hdrgen/hdrgen/header.py b/libc/utils/hdrgen/hdrgen/header.py
index 11e0234eda1cf..78444ed377be1 100644
--- a/libc/utils/hdrgen/hdrgen/header.py
+++ b/libc/utils/hdrgen/hdrgen/header.py
@@ -43,6 +43,7 @@
     "bsd": "BSD",
     "gnu": "GNU",
     "linux": "Linux",
+    "uefi": "UEFI",
 }
 
 HEADER_TEMPLATE = """\

github-actions · 2025-03-14T00:39:08Z

✅ With the latest revision this PR passed the C/C++ code formatter.

lntue · 2025-03-14T01:48:32Z

libc/src/__support/OSUtil/uefi/exit.cpp

+namespace internal {
+
+[[noreturn]] void exit(int status) {
+  efi_system_table->BootServices->Exit(efi_image_handle, status, 0, NULL);


nullptr instead of NULL

michaelrj-google

This looks fine for now, but you need to get a buildbot ready before it lands.

RossComputerGuy · 2025-03-14T18:40:16Z

How would one do that? Also, we cannot natively build in UEFI until someone writes a compiler that can run in UEFI lol.

lntue · 2025-03-14T18:44:02Z

This looks fine for now, but you need to get a buildbot ready before it lands.

I think for new targets like this, it's ok as long as there is a plan for a buildbot setup in the near future.
Essentially, these initial commits are needed in order to setting up a CI for the targets.

RossComputerGuy · 2025-03-14T18:45:42Z

Yeah, I think we need to be able to essentially bootstrap a toolchain for UEFI by doing a cross compile of LLVM components. We can certainly set up the pre-commits to at least try and compile things.

michaelrj-google · 2025-03-14T18:46:06Z

Here's the relevant policy: https://libc.llvm.org/porting.html#id5

You don't need a native UEFI builder, as long as you can provide a cmake command it should be straightforward to add it to one of our existing builders in the config: https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-linux.py

michaelrj-google · 2025-03-14T18:47:35Z

This looks fine for now, but you need to get a buildbot ready before it lands.

I think for new targets like this, it's ok as long as there is a plan for a buildbot setup in the near future. Essentially, these initial commits are needed in order to setting up a CI for the targets.

I'm fine with just having a plan, but that plan needs to be ready before the target lands. If we put off testing, it has a tendency to get forgotten.

RossComputerGuy · 2025-03-14T18:49:05Z

Gotcha, yeah I might need some additional guidance on getting it set up. I'm very much open to having buildbots.

lntue · 2025-03-14T18:50:29Z

Here's the relevant policy: https://libc.llvm.org/porting.html#id5

You don't need a native UEFI builder, as long as you can provide a cmake command it should be straightforward to add it to one of our existing builders in the config: https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-linux.py

Adding a build-only precommit one right after landing this SGTM.

RossComputerGuy · 2025-03-14T19:00:15Z

Adding a build-only precommit one right after landing this SGTM.

That will be #131376

michaelrj-google

LGTM, thanks for getting that set up

Adds documentation for the UEFI target since #131246 was merged.

Comes after #131246 to enable UEFI being build. Skips tests until we have set up testing.

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

llvmbot added the libc label Mar 14, 2025

RossComputerGuy force-pushed the feat/uefi-target-init branch from 8077301 to 7768251 Compare March 14, 2025 00:41

lntue requested a review from frobtech March 14, 2025 01:47

lntue reviewed Mar 14, 2025

View reviewed changes

[libc] init uefi

d9c81fb

RossComputerGuy force-pushed the feat/uefi-target-init branch from 7768251 to d9c81fb Compare March 14, 2025 02:44

jhuber6 approved these changes Mar 14, 2025

View reviewed changes

michaelrj-google reviewed Mar 14, 2025

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RossComputerGuy mentioned this pull request Mar 14, 2025

[libc] add uefi fullbuild to workflows #131376

Merged

michaelrj-google approved these changes Mar 14, 2025

View reviewed changes

RossComputerGuy merged commit bb69499 into llvm:main Mar 15, 2025
16 checks passed

RossComputerGuy deleted the feat/uefi-target-init branch March 15, 2025 03:15

RossComputerGuy mentioned this pull request Mar 15, 2025

[libc] add uefi docs #131426

Merged

RossComputerGuy added a commit that referenced this pull request Mar 16, 2025

[libc] add uefi docs (#131426)

4e841d7

Adds documentation for the UEFI target since #131246 was merged.

RossComputerGuy added a commit that referenced this pull request Apr 30, 2025

[libc] add uefi fullbuild to workflows (#131376)

e9193f5

Comes after #131246 to enable UEFI being build. Skips tests until we have set up testing.

IanWood1 pushed a commit to IanWood1/llvm-project that referenced this pull request May 6, 2025

[libc] add uefi fullbuild to workflows (llvm#131376)

a02d82d

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

IanWood1 pushed a commit to IanWood1/llvm-project that referenced this pull request May 6, 2025

[libc] add uefi fullbuild to workflows (llvm#131376)

342dd49

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

IanWood1 pushed a commit to IanWood1/llvm-project that referenced this pull request May 6, 2025

[libc] add uefi fullbuild to workflows (llvm#131376)

24ffc88

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

GeorgeARM pushed a commit to GeorgeARM/llvm-project that referenced this pull request May 7, 2025

[libc] add uefi fullbuild to workflows (llvm#131376)

43e73f0

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

Ankur-0429 pushed a commit to Ankur-0429/llvm-project that referenced this pull request May 9, 2025

[libc] add uefi fullbuild to workflows (llvm#131376)

7c022ef

Comes after llvm#131246 to enable UEFI being build. Skips tests until we have set up testing.

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