[Buildroot] [PATCH 1/2] webrtc-audio-processing: fix build on ARM Cortex-M
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Sat Aug 6 10:02:44 UTC 2016
The webrtc-audio-processing configure script assumes that if the
host_cpu part of the tuple is "arm", then ARM instructions are
available. This is obviously incorrect for ARM Cortex-M platforms, which
only support the Thumb-2 instruction set.
In order to address this, we add a patch,
0001-configure.ac-fix-architecture-detection.patch, which changes how
webrtc-audio-processing detects the architecture: instead of relying on
the host_cpu part of the tuple, it relies on the built-in definitions of
the compiler.
Not only it fixes the Cortex-M detection, but it also enables ARMv7
optimizations on ARMv7-A: until now they were only enabled when the
host_cpu part of the tuple was armv7, which is never the case in
Buildroot.
However, once this issue is fixed for Cortex-M, the build nonetheless
fails later due to the usage of NPTL-only functions. So we change the
thread dependency to a NPTL dependency.
Fixes:
http://autobuild.buildroot.net/results/4933082cd7cc5781404c77ccef5c2b9333c5f714/
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
...1-configure.ac-fix-architecture-detection.patch | 84 ++++++++++++++++++++++
package/webrtc-audio-processing/Config.in | 7 +-
.../webrtc-audio-processing.mk | 2 +
3 files changed, 90 insertions(+), 3 deletions(-)
create mode 100644 package/webrtc-audio-processing/0001-configure.ac-fix-architecture-detection.patch
diff --git a/package/webrtc-audio-processing/0001-configure.ac-fix-architecture-detection.patch b/package/webrtc-audio-processing/0001-configure.ac-fix-architecture-detection.patch
new file mode 100644
index 0000000..d0ea4bd
--- /dev/null
+++ b/package/webrtc-audio-processing/0001-configure.ac-fix-architecture-detection.patch
@@ -0,0 +1,84 @@
+From 233413841882608c6d5b98b6ce89fcb8a292db82 Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
+Date: Sat, 6 Aug 2016 10:22:34 +0200
+Subject: [PATCH] configure.ac: fix architecture detection
+
+The current architecture detection, based on the "host_cpu" part of the
+tuple does not work properly for a number of reason:
+
+ - The code assumes that if host_cpu starts with "arm" then ARM
+ instructions are available, which is incorrect. Indeed, Cortex-M
+ platforms can run Linux, they are ARM platforms (so host_cpu = arm),
+ but they don't support ARM instructions: they support only the
+ Thumb-2 instruction set.
+
+ - The armv7 case is also not very useful, as it is not standard at all
+ to pass armv7 as host_cpu even if the host system is actually ARMv7
+ based.
+
+ - For the same reason, the armv8 case is not very useful: armv8 is
+ never used as the host_cpu part of a tuple.
+
+So, this commit moves away from a host_cpu based logic, and instead
+tests using AC_CHECK_DECLS() the built-in definitions of the compiler:
+
+ - If we have __ARM_ARCH_ISA_ARM defined, then it's an ARM processor
+ that supports the ARM instruction set (this allows to exclude Thumb-2
+ only processors).
+
+ - If we have __ARM_ARCH_7A__, then we have an ARMv7-A processor, and
+ we can enable the corresponding optimizations
+
+ - Same for __i386__ and __x86_64__.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
+---
+Submitted upstream, under a slightly different form so that it applies
+on master:
+
+ https://lists.freedesktop.org/archives/pulseaudio-discuss/2016-August/026600.html
+---
+ configure.ac | 27 +++++++++------------------
+ 1 file changed, 9 insertions(+), 18 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 6f9553b..836c6ad 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -55,24 +55,15 @@ AS_CASE(["${host}"],
+ )
+ AC_SUBST(PLATFORM_CFLAGS)
+
+-AS_CASE(["${host_cpu}"],
+- [i?86|x86_64],
+- [
+- HAVE_X86=1
+- ],
+- [armv7*|armv8*],
+- [
+- HAVE_ARM=1
+- HAVE_ARMV7=1
+- ARCH_CFLAGS="-DWEBRTC_ARCH_ARM -DWEBRTC_ARCH_ARM_V7"
+- ],
+- [arm*],
+- [
+- HAVE_ARM=1
+- ARCH_CFLAGS="-DWEBRTC_ARCH_ARM"
+- ]
+- # FIXME: Add MIPS support, see webrtc/BUILD.gn for defines
+-)
++# Testing __ARM_ARCH_ISA_ARM since the code contains ARM instructions,
++# which don't work on Thumb-2 only platforms (ARMv7-M).
++AC_CHECK_DECLS([__ARM_ARCH_ISA_ARM],
++ [HAVE_ARM=1; ARCH_CFLAGS="${ARCH_CFLAGS} -DWEBRTC_ARCH_ARM"])
++AC_CHECK_DECLS([__ARM_ARCH_7A__],
++ [HAVE_ARMV7=1; ARCH_CFLAGS="${ARCH_CFLAGS} -DWEBRTC_ARCH_ARM_V7"])
++AC_CHECK_DECLS([__i386__], [HAVE_X86=1])
++AC_CHECK_DECLS([__x86_64__], [HAVE_X86=1])
++
+ AM_CONDITIONAL(HAVE_X86, [test "x${HAVE_X86}" = "x1"])
+ AM_CONDITIONAL(HAVE_ARM, [test "x${HAVE_ARM}" = "x1"])
+ AM_CONDITIONAL(HAVE_ARMV7, [test "x${HAVE_ARMV7}" = "x1"])
+--
+2.7.4
+
diff --git a/package/webrtc-audio-processing/Config.in b/package/webrtc-audio-processing/Config.in
index 7c69903..79a06d8 100644
--- a/package/webrtc-audio-processing/Config.in
+++ b/package/webrtc-audio-processing/Config.in
@@ -3,14 +3,15 @@ config BR2_PACKAGE_WEBRTC_AUDIO_PROCESSING
depends on BR2_arm || BR2_i386 || BR2_x86_64
depends on BR2_INSTALL_LIBSTDCPP
depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
- depends on BR2_TOOLCHAIN_HAS_THREADS
+ # pthread_condattr_setclock
+ depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
help
AudioProcessing library based on Google's implementation of
WebRTC.
http://freedesktop.org/software/pulseaudio/webrtc-audio-processing/
-comment "webrtc-audio-processing needs a toolchain w/ C++, threads, gcc >= 4.8"
+comment "webrtc-audio-processing needs a toolchain w/ C++, NPTL, gcc >= 4.8"
depends on BR2_arm || BR2_i386 || BR2_x86_64
- depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS \
+ depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS_NPTL \
|| !BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
diff --git a/package/webrtc-audio-processing/webrtc-audio-processing.mk b/package/webrtc-audio-processing/webrtc-audio-processing.mk
index 587f1aa..5a5d1ce 100644
--- a/package/webrtc-audio-processing/webrtc-audio-processing.mk
+++ b/package/webrtc-audio-processing/webrtc-audio-processing.mk
@@ -10,6 +10,8 @@ WEBRTC_AUDIO_PROCESSING_SITE = http://freedesktop.org/software/pulseaudio/webrtc
WEBRTC_AUDIO_PROCESSING_INSTALL_STAGING = YES
WEBRTC_AUDIO_PROCESSING_LICENSE = BSD-3c
WEBRTC_AUDIO_PROCESSING_LICENSE_FILES = COPYING
+# 0001-configure.ac-fix-architecture-detection.patch
+WEBRTC_AUDIO_PROCESSING_AUTORECONF = YES
ifeq ($(BR2_SOFT_FLOAT),y)
WEBRTC_AUDIO_PROCESSING_CONF_OPTS += --with-ns-mode=fixed
--
2.7.4
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