bsp/x86_64: Minimal bootable BSP

Current state:

  - Basic context initialization and switching code.
  - Stubbed console (empty functions).
  - Mostly functional linker script (may need tweaks if we ever want to move
    away from the large code model (see: CPU_CFLAGS).
  - Fully functional boot, by using FreeBSD's bootloader to load RTEMS's ELF for
    UEFI-awareness.

In short, the current state with this commit lets us boot, go through the system
initialization functions, and then call user application's Init task too.

Updates #2898.

1 files changed, 47 insertions, 0 deletions

diff --git a/bsps/x86_64/amd64/include/start.h b/bsps/x86_64/amd64/include/start.h
new file mode 100644
index 0000000000..eee249e3a6
--- /dev/null
+++ b/bsps/x86_64/amd64/include/start.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2018.
+ * Amaan Cheval <amaan.cheval@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef LIBBSP_AMD64_START_H
+#define LIBBSP_AMD64_START_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @brief Entry point for generated ELF.
+ *
+ * The linkcmds script sets this function as the entry point, to be jumped into
+ * the bootloader. It calls boot_card and kicks the whole RTEMS initialization
+ * process off.
+ */
+void _start(void);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* LIBBSP_AMD64_START_H */