From 5a91fec1a80939e78e37a0b2bc1d3043dcac23f4 Mon Sep 17 00:00:00 2001
From: Alistair Francis <alistair.francis@wdc.com>
Date: Thu, 17 Jan 2019 17:33:47 -0800
Subject: platform/qemu/virt: Dynamically calculate xlen

The QEMU virt machine can be either 32 or 66 bit. Don't hard code the
CPU bit length and instead let the compiler determine it.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 Makefile                     |  3 +++
 platform/qemu/virt/config.mk | 13 +++++++++++--
 platform/template/config.mk  |  2 ++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 6f67c54..2848d09 100644
--- a/Makefile
+++ b/Makefile
@@ -116,6 +116,9 @@ endif
 AS		=	$(CC)
 DTC		=	dtc
 
+# Guess the compillers xlen
+OPENSBI_CC_XLEN = `expr substr \`$(CC) -dumpmachine\`  6 2`
+
 # Setup compilation commands flags
 CFLAGS		=	-g -Wall -Werror -nostdlib -fno-strict-aliasing -O2
 CFLAGS		+=	-fno-omit-frame-pointer -fno-optimize-sibling-calls
diff --git a/platform/qemu/virt/config.mk b/platform/qemu/virt/config.mk
index 1ee66d0..5931d0e 100644
--- a/platform/qemu/virt/config.mk
+++ b/platform/qemu/virt/config.mk
@@ -9,8 +9,17 @@
 
 # Compiler flags
 platform-cppflags-y =
-platform-cflags-y =-mabi=lp64 -march=rv64imafdc -mcmodel=medany
-platform-asflags-y =-mabi=lp64 -march=rv64imafdc -mcmodel=medany
+# If we know the compillers xlen use it below
+ifeq ($(OPENSBI_CC_XLEN), 32)
+	platform-cflags-y =-mabi=ilp$(OPENSBI_CC_XLEN) -march=rv$(OPENSBI_CC_XLEN)imafdc
+	platform-asflags-y =-mabi=ilp$(OPENSBI_CC_XLEN) -march=rv$(OPENSBI_CC_XLEN)imafdc
+endif
+ifeq ($(OPENSBI_CC_XLEN), 64)
+	platform-cflags-y =-mabi=lp$(OPENSBI_CC_XLEN) -march=rv$(OPENSBI_CC_XLEN)imafdc
+	platform-asflags-y =-mabi=lp$(OPENSBI_CC_XLEN) -march=rv$(OPENSBI_CC_XLEN)imafdc
+endif
+platform-cflags-y +=  -mcmodel=medany
+platform-asflags-y += -mcmodel=medany
 platform-ldflags-y =
 
 # Common drivers to enable
diff --git a/platform/template/config.mk b/platform/template/config.mk
index b1457da..21aa6d6 100644
--- a/platform/template/config.mk
+++ b/platform/template/config.mk
@@ -12,6 +12,8 @@ platform-cppflags-y =
 # 	-mabi=lp64 -march=rv64imafdc -mcmodel=medany
 # For a 32 bits platform, this will likely be:
 # 	-mabi=lp32 -march=rv32imafdc -mcmodel=medlow
+# You can also use the Makefile variable OPENSBI_CC_XLEN for the xlen
+# See the QEMU virt machine for an example of this
 platform-cflags-y = -mabi=lp64 -march=rv64imafdc -mcmodel=medany
 platform-asflags-y = -mabi=lp64 -march=rv64imafdc -mcmodel=medany
 
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