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openblas: fix build issues on ARM

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This commit fixes several build issues of OpenBLAS on ARM:

 - The first one occured on ARMv5 platforms, when the ARMV5 OpenBLAS
   architecture is used. In this case, OpenBLAS build system forces
   -march=armv5, which may not be correct for certain toolchains. As an
   example, the Sourcery CodeBench toolchain has an ARMv4 and an ARMv5
   sysroot. The ARMv5 sysroot is actually an armv5te sysroot, so when
   OpenBLAS forces -march=armv5, gcc thinks it should use the ARMv4
   sysroot, causing build failures.

   To address this, a patch to completely remove the -march ARM CFLAGS
   is added to OpenBLAS.

   Fixes:

     http://autobuild.buildroot.net/results/991497b12b70f948169e5ad99eebd0fe7f6209a2/

 - The second one occured on ARMv7 platforms, when the ARMV7 OpenBLAS
   architecture is used. The OpenBLAS code expects an EABIhf build, so a
   dependency is added for EABIhf for both ARMv6 and ARMv7.

   Fixes:

     http://autobuild.buildroot.net/results/0ba0bee48a83367fcefab827e8eaa72f0c8fe90b/

 - Once the previous ARMv7 problem has been fixed, it turns out that the
   ARMv7 specific code in OpenBLAS contains VFPv3 specific
   code. Therefore, the user *must* have choosen either VFPv3 or VFPv4,
   or the code will not build. VFPv3-D16/VFPv4-D16 are not sufficient,
   as more than 16 registers are used by the OpenBLAS code.

   To address this, the ARMV7 platform of OpenBLAS is restricted to the
   proper VFPv3/VFPv4 selection, and the ARMV6 platform is restricted to
   the proper VFPv2 selection.

   This problem was not visible in the autobuilders, as it was hidden by
   the previous one.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Thomas Petazzoni 2016-08-07 23:32:34 +02:00
parent c0a5fdf188
commit caf8074cb4
2 changed files with 88 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
package/openblas/0002-Makefile.arm-remove-march-flags.patch Normal file
View File

@ -0,0 +1,73 @@
From 71b9e9b7f080c464777d07bd1a917a1c449d2ef8 Mon Sep 17 00:00:00 2001
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date: Sun, 7 Aug 2016 23:20:00 +0200
Subject: [PATCH] Makefile.arm: remove -march flags
The provided -march flags, especially for ARMv5 and ARMv6 may not
necessarily match the needed ones: for ARMv5, it might be armv5,
armv5te, armv5t, etc. If the wrong one is used, the incorrect toolchain
sysroot can be used in a multilib toolchain.
Therefore, let the user building OpenBLAS pass the appropriate -march
flag.
The other flags, such as -mfpu=vfp or -mfloat-abi=hard are kept, as they
are actually required for the build to proceed (OpenBLAS uses VFP
instructions, and assume an EABIhf ABI).
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
Makefile.arm | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/Makefile.arm b/Makefile.arm
index 62bf275..c0d6ab8 100644
--- a/Makefile.arm
+++ b/Makefile.arm
@@ -1,31 +1,31 @@
# ifeq logical or
ifeq ($(CORE), $(filter $(CORE),CORTEXA9 CORTEXA15))
ifeq ($(OSNAME), Android)
-CCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -march=armv7-a
-FCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -march=armv7-a
+CCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard
+FCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard
else
-CCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard -march=armv7-a
-FCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard -march=armv7-a
+CCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard
+FCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard
endif
endif
ifeq ($(CORE), ARMV7)
ifeq ($(OSNAME), Android)
-CCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -march=armv7-a -Wl,--no-warn-mismatch
-FCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -march=armv7-a -Wl,--no-warn-mismatch
+CCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -Wl,--no-warn-mismatch
+FCOMMON_OPT += -marm -mfpu=neon -mfloat-abi=hard -Wl,--no-warn-mismatch
else
-CCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard -march=armv7-a
-FCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard -march=armv7-a
+CCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard
+FCOMMON_OPT += -marm -mfpu=vfpv3 -mfloat-abi=hard
endif
endif
ifeq ($(CORE), ARMV6)
-CCOMMON_OPT += -marm -mfpu=vfp -mfloat-abi=hard -march=armv6
-FCOMMON_OPT += -marm -mfpu=vfp -mfloat-abi=hard -march=armv6
+CCOMMON_OPT += -marm -mfpu=vfp -mfloat-abi=hard
+FCOMMON_OPT += -marm -mfpu=vfp -mfloat-abi=hard
endif
ifeq ($(CORE), ARMV5)
-CCOMMON_OPT += -marm -march=armv5
-FCOMMON_OPT += -marm -march=armv5
+CCOMMON_OPT += -marm
+FCOMMON_OPT += -marm
endif
--
2.7.4

19
package/openblas/Config.in
View File

@ -32,11 +32,22 @@ config BR2_PACKAGE_OPENBLAS_DEFAULT_TARGET
# I6400 is built with MSA support which is only available in Codescape toolchains
default "I6400" if BR2_mips_64r6 && BR2_TOOLCHAIN_EXTERNAL_CODESCAPE_IMG_MIPS
default "SPARC" if BR2_sparc
default "CORTEXA15" if BR2_cortex_a15
default "CORTEXA9" if BR2_cortex_a9
# Cortex-A15 always have a VFPv4
default "CORTEXA15" if (BR2_cortex_a15 && BR2_ARM_EABIHF)
# Cortex-A9 have an optional VFPv3, so we need to make sure it
# is available
default "CORTEXA9" if (BR2_cortex_a9 && BR2_ARM_EABIHF && \
BR2_ARM_CPU_HAS_VFPV3)
default "ARMV5" if BR2_ARM_CPU_ARMV5
default "ARMV6" if BR2_ARM_CPU_ARMV6
default "ARMV7" if BR2_ARM_CPU_ARMV7A
# On ARMv6, OpenBLAS assumes that a VFP is available, and
# EABIhf is used
default "ARMV6" if (BR2_ARM_CPU_ARMV6 && BR2_ARM_EABIHF && \
BR2_ARM_CPU_HAS_VFPV2)
# On ARMv7, OpenBLAS assumes that a full VFPv3+ is available
# (and not the more limited D16 variant), and that EABIhf is
# used.
default "ARMV7" if (BR2_ARM_CPU_ARMV7A && BR2_ARM_EABIHF && \
BR2_ARM_CPU_HAS_VFPV3)
default "ARMV8" if BR2_aarch64 || BR2_aarch64_be
help
OpenBLAS target CPU. See TargetList.txt in the source tree for