git: e664cd1dc5fb - releng/13.4 - Fix EFI loader reproducibility with lld

The branch releng/13.4 has been updated by dim:

URL: https://cgit.FreeBSD.org/src/commit/?id=e664cd1dc5fb66d0802db84f469a5c500dd3688a

commit e664cd1dc5fb66d0802db84f469a5c500dd3688a
Author:     Dimitry Andric <dim@FreeBSD.org>
AuthorDate: 2024-08-11 19:48:27 +0000
Commit:     Dimitry Andric <dim@FreeBSD.org>
CommitDate: 2024-08-15 07:42:36 +0000

    Fix EFI loader reproducibility with lld
    
    When the various loaders under stand/efi are built, the resulting
    binaries differ over multiple runs, even if WITH_REPRODUCIBLE_BUILD is
    used. This is caused by lld multithreading and the custom linker scripts
    for the loaders, and affects the following binaries:
    
    * loader_4th.efi
    * loader_4th.sym
    * loader_4th.sym.full
    * loader_lua.efi
    * loader_lua.sym
    * loader_lua.sym.full
    * loader_simp.efi
    * loader_simp.sym
    * loader_simp.sym.full
    
    Work around this by disabling lld threading for these binaries.
    
    Reviewed by:    emaste
    Approved by:    re (cperciva)
    MFC after:      3 days
    Differential Revision: https://reviews.freebsd.org/D46271
    
    (cherry picked from commit f5ce3f4ef562ea9fc4d8f9c13c268f48a5bacba7)
    (cherry picked from commit 8a4fd438ef6c874110b9ed320d3cd54e2bf93459)
---
 stand/efi/loader/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/stand/efi/loader/Makefile b/stand/efi/loader/Makefile
index ec2a147bd69f..c5503da655f9 100644
--- a/stand/efi/loader/Makefile
+++ b/stand/efi/loader/Makefile
@@ -105,6 +105,11 @@ LDFLAGS+=	-Wl,-T${LDSCRIPT},-Bsymbolic,-znotext -pie
 LDFLAGS+=	-Wl,--no-dynamic-linker
 .endif
 
+# When lld is using multiple threads, which it does by default, it can
+# result in non-reproducible output with the custom linker script. Work
+# around this by disabling threading.
+LDFLAGS.lld+=	-Wl,--threads=1
+
 CLEANFILES+=	${LOADER}.efi
 
 ${LOADER}.efi: ${PROG}