Re: [Xen-devel] [PATCH v15 05/10] x86: add multiboot2 protocol support for EFI platforms

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Tue, Feb 14, 2017 at 07:33:24PM +0100, Daniel Kiper wrote:
> This way Xen can be loaded on EFI platforms using GRUB2 and
> other boot loaders which support multiboot2 protocol.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>

I am posting diff between v14 and v15 for your convenience.

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 5147204..eb738d4 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -394,10 +394,18 @@ __start:

         /* EFI IA-32 platforms are not supported. */
         cmpl    $MULTIBOOT2_TAG_TYPE_EFI32,MB2_tag_type(%ecx)
+        /*
+         * Here we should zap vga_text_buffer. However, we can disable
+         * VGA updates in simpler and more reliable way later.
+         */
         je      .Lmb2_efi_ia_32

         /* Bootloader shutdown EFI x64 boot services. */
         cmpl    $MULTIBOOT2_TAG_TYPE_EFI64,MB2_tag_type(%ecx)
+        /*
+         * Here we should zap vga_text_buffer. However, we can disable
+         * VGA updates in simpler and more reliable way later.
+         */
         je      .Lmb2_no_bs

         /* Is it the end of Multiboot2 information? */
diff --git a/xen/arch/x86/efi/stub.c b/xen/arch/x86/efi/stub.c
index 2127cce..17da050 100644
--- a/xen/arch/x86/efi/stub.c
+++ b/xen/arch/x86/efi/stub.c
@@ -34,10 +34,10 @@ void __init noreturn efi_multiboot2(EFI_HANDLE ImageHandle,
      * not be directly supported by C compiler.
      */
     asm volatile(
-    "    call *%2                     \n"
+    "    call *%3                     \n"
     "0:  hlt                          \n"
     "    jmp  0b                      \n"
-       : "+c" (StdErr) : "d" (err), "rm" (StdErr->OutputString)
+       : "+c" (StdErr), "=d" (StdErr) : "1" (err), "rm" (StdErr->OutputString)
        : "rax", "r8", "r9", "r10", "r11", "memory");

     unreachable();

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