![Thomas Petazzoni](/assets/img/avatar_default.png)
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@free-electrons.com>
85 lines
2.9 KiB
Diff
85 lines
2.9 KiB
Diff
From 233413841882608c6d5b98b6ce89fcb8a292db82 Mon Sep 17 00:00:00 2001
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From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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Date: Sat, 6 Aug 2016 10:22:34 +0200
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Subject: [PATCH] configure.ac: fix architecture detection
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The current architecture detection, based on the "host_cpu" part of the
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tuple does not work properly for a number of reason:
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- The code assumes that if host_cpu starts with "arm" then ARM
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instructions are available, which is incorrect. Indeed, Cortex-M
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platforms can run Linux, they are ARM platforms (so host_cpu = arm),
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but they don't support ARM instructions: they support only the
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Thumb-2 instruction set.
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- The armv7 case is also not very useful, as it is not standard at all
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to pass armv7 as host_cpu even if the host system is actually ARMv7
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based.
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- For the same reason, the armv8 case is not very useful: armv8 is
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never used as the host_cpu part of a tuple.
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So, this commit moves away from a host_cpu based logic, and instead
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tests using AC_CHECK_DECLS() the built-in definitions of the compiler:
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- If we have __ARM_ARCH_ISA_ARM defined, then it's an ARM processor
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that supports the ARM instruction set (this allows to exclude Thumb-2
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only processors).
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- If we have __ARM_ARCH_7A__, then we have an ARMv7-A processor, and
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we can enable the corresponding optimizations
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- Same for __i386__ and __x86_64__.
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Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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---
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Submitted upstream, under a slightly different form so that it applies
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on master:
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https://lists.freedesktop.org/archives/pulseaudio-discuss/2016-August/026600.html
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---
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configure.ac | 27 +++++++++------------------
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1 file changed, 9 insertions(+), 18 deletions(-)
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diff --git a/configure.ac b/configure.ac
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index 6f9553b..836c6ad 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -55,24 +55,15 @@ AS_CASE(["${host}"],
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)
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AC_SUBST(PLATFORM_CFLAGS)
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-AS_CASE(["${host_cpu}"],
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- [i?86|x86_64],
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- [
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- HAVE_X86=1
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- ],
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- [armv7*|armv8*],
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- [
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- HAVE_ARM=1
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- HAVE_ARMV7=1
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- ARCH_CFLAGS="-DWEBRTC_ARCH_ARM -DWEBRTC_ARCH_ARM_V7"
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- ],
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- [arm*],
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- [
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- HAVE_ARM=1
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- ARCH_CFLAGS="-DWEBRTC_ARCH_ARM"
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- ]
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- # FIXME: Add MIPS support, see webrtc/BUILD.gn for defines
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-)
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+# Testing __ARM_ARCH_ISA_ARM since the code contains ARM instructions,
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+# which don't work on Thumb-2 only platforms (ARMv7-M).
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+AC_CHECK_DECLS([__ARM_ARCH_ISA_ARM],
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+ [HAVE_ARM=1; ARCH_CFLAGS="${ARCH_CFLAGS} -DWEBRTC_ARCH_ARM"])
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+AC_CHECK_DECLS([__ARM_ARCH_7A__],
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+ [HAVE_ARMV7=1; ARCH_CFLAGS="${ARCH_CFLAGS} -DWEBRTC_ARCH_ARM_V7"])
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+AC_CHECK_DECLS([__i386__], [HAVE_X86=1])
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+AC_CHECK_DECLS([__x86_64__], [HAVE_X86=1])
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+
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AM_CONDITIONAL(HAVE_X86, [test "x${HAVE_X86}" = "x1"])
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AM_CONDITIONAL(HAVE_ARM, [test "x${HAVE_ARM}" = "x1"])
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AM_CONDITIONAL(HAVE_ARMV7, [test "x${HAVE_ARMV7}" = "x1"])
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--
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2.7.4
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