feat: x86_64-montauk userspace cross toolchain

Add build-montauk-toolchain.sh: builds an OS-aware cross GCC/binutils (same versions and prefix as the bare-metal x86_64-elf toolchain) whose x86_64-montauk target links static ET_EXEC binaries against the Montauk libc sysroot with no special flags: 4 KiB max page size for the kernel ELF loader, -mno-red-zone by default, crt1/crti/crtn + -lc from the sysroot, __montauk__ defined. Target patches are checked into toolchain/patches/, the GCC target header into toolchain/files/. sys/types.h now includes <stdint.h> so hosted code (libgcov and friends) sees intptr_t via the stdio include chain. Co-Authored-By: Claude Fable 5 <[email protected]>
2026-07-14 10:19:35 +02:00
parent 182520a585
commit 778f897f1a
7 changed files with 404 additions and 0 deletions
@@ -0,0 +1,41 @@
+/*
+    * montauk.h
+    * GCC target definitions for x86_64-montauk userspace
+    * Copyright (c) 2026 Daniel Hammer
+    *
+    * Programs are static, non-PIE ET_EXEC images loaded by the kernel
+    * ELF loader (kernel/src/Sched/ElfLoader.cpp) at their linked
+    * address. The loader maps 4 KiB pages, so segments must not be
+    * aligned to the 2 MiB x86-64 default.
+*/
+
+#undef TARGET_OS_CPP_BUILTINS
+#define TARGET_OS_CPP_BUILTINS()            \
+    do {                                    \
+        builtin_define("__montauk__");      \
+        builtin_define("__MONTAUK__");      \
+        builtin_assert("system=montauk");   \
+    } while (0)
+
+/* The userspace build convention is -mno-red-zone everywhere; keep it
+   as the target default. A later -mred-zone on the command line still
+   overrides this. */
+#undef CC1_SPEC
+#define CC1_SPEC "-mno-red-zone"
+
+#undef LINK_SPEC
+#define LINK_SPEC \
+    "-m elf_x86_64 -z max-page-size=0x1000 %{shared:-shared} %{!shared:-static}"
+
+/* crt1/crti/crtn come from the Montauk libc (sysroot usr/lib);
+   crtbegin/crtend are GCC's. crti/crtn are empty today (the runtime
+   does not run global constructors yet) but are kept in the link so
+   that enabling them later needs no toolchain change. */
+#undef STARTFILE_SPEC
+#define STARTFILE_SPEC "crt1.o%s crti.o%s crtbegin.o%s"
+
+#undef ENDFILE_SPEC
+#define ENDFILE_SPEC "crtend.o%s crtn.o%s"
+
+#undef LIB_SPEC
+#define LIB_SPEC "-lc"