[xen staging] x86/EFI: Explain buildid.ihex

[patchbot@xxxxxxx]

commit df065aec498e4c3b284601eed3bd6f13b134dd71
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Jun 5 11:01:33 2025 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Jul 29 17:25:54 2025 +0100

    x86/EFI: Explain buildid.ihex
    
    This is an awful lot of magic to only be explained in a commit message.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 xen/arch/x86/efi/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index c6678652fc..3e88f552d2 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -6,6 +6,8 @@ cmd_objcopy_o_ihex = $(OBJCOPY) -I ihex -O binary $< $@
 $(obj)/%.o: $(src)/%.ihex FORCE
        $(call if_changed,objcopy_o_ihex)
 
+# buildid.ihex is an empty COFF object.  It exists for the side effect it has
+# when linking into xen.efi, causing --build-id to attach a .buildid section.
 $(obj)/boot.init.o: $(obj)/buildid.o
 
 $(call cc-option-add,cflags-stack-boundary,CC,-mpreferred-stack-boundary=4)
--
generated by git-patchbot for /home/xen/git/xen.git#staging