On 18/04/2019 10:15, Artem Mygaiev wrote:
Hello Julien, Stefano
Hi Artem,
On Wed, 2019-04-17 at 10:42 +0100, Julien Grall wrote:
Hi,
On 16/04/2019 23:43, Stefano Stabellini wrote:
On Fri, 29 Mar 2019, Julien Grall wrote:
On 28/03/2019 11:27, Artem Mygaiev wrote:
Hi Julien,
Hi Artem,
On Wed, 2019-03-27 at 18:45 +0000, Julien Grall wrote:
Hi all,
This series adds support to build Xen Arm with clang. This series was
tested
with clang 8.0.
Note that I only did build for arm64. I still need to look at the arm32
build.
I wonder if you have time to try the series with Arm Compiler 6? I am
asking because AFAIK it is based on clang/llvm [1] and there's a
safety-compliant version of it certified by TUV [2]. I don't have a
license yet so cannot try it myself but maybe you have access.
I gave a quick try to the Arm Compiler. I had to hack a bit config/StdGNU.mk
to pass armclang and the appropriate target option.
I also had a linking issue at the end where __2snprintf was not found. It
seems the compiler replace snprintf with __2snprintf, I haven't figured out
why yet.
But after these changes, does it work?
I haven't tried to fix the linking issues. I only gave a quick try because Artem
asked. I have no plan at the moment to go further than that for now.
Patches are welcomed to add support for armclang.
I have implemented a bunch of HACKs [1] so can build Xen master with
armclang 6.12. Not even "smoke"-tested, just trying to identify missing
parameters and proper linker configuration.
Thank you for looking at it. Some comments below.
Not yet fixed section placement, lots of warnings from linker like:
Warning: L6170W: Mapping symbol #40 '$x.20' in
.altinstr_replacement(ns16550.o:42) identifies code, but is in a
section not marked as executable.
Instruction in the sections .altinstr_replacement are never meant to be
executed.
I guess this is coming from armlink? Any particular reason to use armlink and
not ld as we do on clang?
Also armlink sometimes fails with Internal fault: [0xe81a5a:6120001]
Do you have more output?
[1] Diff below just for reference with xen master + Julien's clang
patch series applied
---
diff --git a/Config.mk b/Config.mk
index 417039d7f6..0fc84293f9 100644
--- a/Config.mk
+++ b/Config.mk
@@ -221,7 +221,9 @@ CFLAGS += -Wall -Wstrict-prototypes
$(call cc-option-add,HOSTCFLAGS,HOSTCC,-Wdeclaration-after-statement)
$(call cc-option-add,CFLAGS,CC,-Wdeclaration-after-statement)
+ifneq ($(armds),y)
$(call cc-option-add,CFLAGS,CC,-Wno-unused-but-set-variable)
I didn't need this on Arm Compiler 6.11. Can you provide the list of error you
get here?
+endif
$(call cc-option-add,CFLAGS,CC,-Wno-unused-local-typedefs)
LDFLAGS += $(foreach i, $(EXTRA_LIB), -L$(i))
@@ -234,9 +236,15 @@ endif
APPEND_LDFLAGS += $(foreach i, $(APPEND_LIB), -L$(i))
APPEND_CFLAGS += $(foreach i, $(APPEND_INCLUDES), -I$(i))
-EMBEDDED_EXTRA_CFLAGS := -nopie -fno-stack-protector -fno-stack-
protector-all
+EMBEDDED_EXTRA_CFLAGS := -fno-stack-protector -fno-stack-protector-all
EMBEDDED_EXTRA_CFLAGS += -fno-exceptions
+ifeq ($(armds),y)
+EMBEDDED_EXTRA_CFLAGS += -fno-ropi -fno-rwpi
Why do you need this? Is it because armlink does not support -nopie?
+else
+EMBEDDED_EXTRA_CFLAGS += -nopie
+endif
+
XEN_EXTFILES_URL ?= http://xenbits.xen.org/xen-extfiles
# All the files at that location were downloaded from elsewhere on
# the internet. The original download URL is preserved as a comment
diff --git a/config/StdGNU.mk b/config/StdGNU.mk
index 48c50b5ad7..585d076d4f 100644
--- a/config/StdGNU.mk
+++ b/config/StdGNU.mk
@@ -1,6 +1,15 @@
AS = $(CROSS_COMPILE)as
+AR = $(CROSS_COMPILE)ar
LD = $(CROSS_COMPILE)ld
ifeq ($(clang),y)
+ifeq ($(armds),y)
+CC = armclang
+CXX = armclang
+LD_LTO = armlink
+LD = armlink -v
+AS = armasm
+AR = armar
+else
ifneq ($(CROSS_COMPILE),)
CC = clang -target $(CROSS_COMPILE:-=)
CXX = clang++ -target $(CROSS_COMPILE:-=)
@@ -9,13 +18,13 @@ CC = clang
CXX = clang++
endif
LD_LTO = $(CROSS_COMPILE)llvm-ld
+endif
else
CC = $(CROSS_COMPILE)gcc
CXX = $(CROSS_COMPILE)g++
LD_LTO = $(CROSS_COMPILE)ld
endif
CPP = $(CC) -E
-AR = $(CROSS_COMPILE)ar
RANLIB = $(CROSS_COMPILE)ranlib
NM = $(CROSS_COMPILE)nm
STRIP = $(CROSS_COMPILE)strip
diff --git a/config/arm32.mk b/config/arm32.mk
index f95228e3c0..5afed07357 100644
--- a/config/arm32.mk
+++ b/config/arm32.mk
@@ -4,12 +4,14 @@ CONFIG_ARM_$(XEN_OS) := y
CONFIG_XEN_INSTALL_SUFFIX :=
-# -march= -mcpu=
-
# Explicitly specifiy 32-bit ARM ISA since toolchain default can be
-mthumb:
-CFLAGS += -marm
-
+ifeq ($(armds),y)
+# VE needed
+CFLAGS += --target=arm-arm-none-eabi -march=armv7-a
-marm should do the right thing even on armclang.
You would still need --target=.... but that's should depend on $CROSS_COMPILE
(or any other name we decide).
+else
+CFLAGS += -marm # -march= -mcpu=
# Use only if calling $(LD) directly.
LDFLAGS_DIRECT += -EL
+endif
IOEMU_CPU_ARCH ?= arm
diff --git a/config/arm64.mk b/config/arm64.mk
index aa45772b61..46b203d384 100644
--- a/config/arm64.mk
+++ b/config/arm64.mk
@@ -4,10 +4,14 @@ CONFIG_ARM_$(XEN_OS) := y
CONFIG_XEN_INSTALL_SUFFIX :=
+ifeq ($(armds),y)
+# VE needed
+CFLAGS += --target=aarch64-arm-none-eabi -march=armv8.1-a+nofp+nosimd
Same remark for --target.
Also, -march=armv8.1 looks wrong to me because this may generate code that will
not work on armv8.0 platform.
+else
CFLAGS += #-marm -march= -mcpu= etc
-
# Use only if calling $(LD) directly.
LDFLAGS_DIRECT += -EL
+endif
IOEMU_CPU_ARCH ?= aarch64
diff --git a/xen/Rules.mk b/xen/Rules.mk
index a151b3f625..72b34451d2 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -76,9 +76,11 @@ AFLAGS-y += -D__ASSEMBLY__
# Older clang's built-in assembler doesn't understand .skip with
labels:
# https://bugs.llvm.org/show_bug.cgi?id=27369
ifeq ($(clang),y)
+ifneq ($(armds),y)
$(call as-option-add,CFLAGS,CC,".L0:\n.L1:\n.skip (.L1 - .L0)",,\
-no-integrated-as)
endif
+endif
ALL_OBJS := $(ALL_OBJS-y)
Cheers,
--
Julien Grall
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