Adding support for Xen for x86 (32bit and 64bit)

portable/GCC/XEN_x86/x86-64/asm_src/xennote.S

@@ -0,0 +1,40 @@
+ # xennote 
+ # 
+ # Copyright (C) 2025 Advanced Micro Devices, Inc. or its affiliates. All Rights Reserved.
+ #
+ # SPDX-License-Identifier: MIT
+ #
+ # Permission is hereby granted, free of charge, to any person obtaining a copy of
+ # this software and associated documentation files (the "Software"), to deal in
+ # the Software without restriction, including without limitation the rights to
+ # use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ # the Software, and to permit persons to whom the Software is furnished to do so,
+ # subject to the following conditions:
+ #
+ # The above copyright notice and this permission notice shall be included in all
+ # copies or substantial portions of the Software.
+ #
+ # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ # FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ # COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ # IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ #
+
+.extern start
+#define ELFNOTE(name, type, desc)           \
+    .pushsection .note.name               ; \
+    .align 4                              ; \
+    .long 2f - 1f       /* namesz */      ; \
+    .long 4f - 3f       /* descsz */      ; \
+    .long type          /* type   */      ; \
+1:.asciz #name          /* name   */      ; \
+2:.align 4                                ; \
+3:desc                  /* desc   */      ; \
+4:.align 4                                ; \
+    .popsection
+
+#define XEN_ELFNOTE_PHYS32_ENTRY 18
+ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .long start)
+