[xen staging] x86/boot: Don't use INC to set defaults

[patchbot@xxxxxxx]

commit 163338e6fbec2c549d55782e1ae4cf238b793f4a
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Oct 3 15:03:38 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Oct 3 18:07:36 2024 +0100

    x86/boot: Don't use INC to set defaults
    
    __efi64_mb2_start() makes some bold assumptions about the efi_platform and
    skip_realmode booleans.  Set them to 1 explicitly, which is more robust.
    
    Make the comment a little more concise.
    
    No practical change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/boot/head.S | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index d1856d8012..af776c201a 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -279,14 +279,12 @@ __efi64_mb2_start:
         pop     %rbx
         pop     %rax
 
-        /* We are on EFI platform and EFI boot services are available. */
-        incb    efi_platform(%rip)
-
         /*
-         * Disable real mode and other legacy stuff which should not
-         * be run on EFI platforms.
+         * efi_multiboot2_prelude() is happy that we're on EFI platform.  Skip
+         * the BIOS initialisation path.
          */
-        incb    skip_realmode(%rip)
+        movb    $1, efi_platform(%rip)
+        movb    $1, skip_realmode(%rip)
 
         /* Jump to trampoline_setup after switching CPU to x86_32 mode. */
         lea     trampoline_setup(%rip),%r15
--
generated by git-patchbot for /home/xen/git/xen.git#staging