From a2e2311a40696e39eb24ff4a4d4c0968bba42c8c Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Fri, 24 Apr 2020 10:03:11 +0000
Subject: [PATCH] Build the arm64 loader with -ffixed-x18

This stops the compiler from using the x18 register. Some UEFI
implementations assume this will be preserved when calling the Boot
Services.

MFC after:	2 weeks
Sponsored by:	Innovate UK
---
 stand/defs.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stand/defs.mk b/stand/defs.mk
index 8d41c5f6f1b2..89ccf2f4bdbf 100644
--- a/stand/defs.mk
+++ b/stand/defs.mk
@@ -119,7 +119,7 @@ SSP_CFLAGS=
 # currently has no /boot/loader, but may soon.
 CFLAGS+=	-ffreestanding ${CFLAGS_NO_SIMD}
 .if ${MACHINE_CPUARCH} == "aarch64"
-CFLAGS+=	-mgeneral-regs-only -fPIC
+CFLAGS+=	-mgeneral-regs-only -ffixed-x18 -fPIC
 .elif ${MACHINE_CPUARCH} == "riscv"
 CFLAGS+=	-march=rv64imac -mabi=lp64
 .else