libv8 version 3.4.14.21-5 failed to build on armel

[James Page]

Error from build log:

g++ -o obj/release/arm/lithium-gap-resolver-arm.os -c -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -Werror=format-security -Wall -Wno-psabi -fno-rtti -fno-exceptions -fvisibility=hidden -fno-tree-sink -mno-thumb-interwork -Wall -Werror -W -Wno-unused-parameter -Wno-unused-but-set-variable -Wnon-virtual-dtor -Wno-abi -pedantic -mfloat-abi=soft -O2 -fomit-frame-pointer -fdata-sections -ffunction-sections -ansi -fPIC -D_FORTIFY_SOURCE=2 -DCAN_USE_UNALIGNED_ACCESSES=0 -DUSE_EABI_HARDFLOAT=0 -DV8_TARGET_ARCH_ARM -DV8_SHARED -DENABLE_DEBUGGER_SUPPORT -Isrc -I. src/arm/lithium-gap-resolver-arm.cc
g++ -o obj/release/arm/macro-assembler-arm.os -c -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -Werror=format-security -Wall -Wno-psabi -fno-rtti -fno-exceptions -fvisibility=hidden -fno-tree-sink -mno-thumb-interwork -Wall -Werror -W -Wno-unused-parameter -Wno-unused-but-set-variable -Wnon-virtual-dtor -Wno-abi -pedantic -mfloat-abi=soft -O2 -fomit-frame-pointer -fdata-sections -ffunction-sections -ansi -fPIC -D_FORTIFY_SOURCE=2 -DCAN_USE_UNALIGNED_ACCESSES=0 -DUSE_EABI_HARDFLOAT=0 -DV8_TARGET_ARCH_ARM -DV8_SHARED -DENABLE_DEBUGGER_SUPPORT -Isrc -I. src/arm/macro-assembler-arm.cc
src/arm/macro-assembler-arm.cc:56:2: error: #error "flag -mthumb-interwork missing"
scons: *** [obj/release/arm/macro-assembler-arm.os] Error 1
scons: building terminated because of errors.
make: *** [debian/stamp-scons-build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2

https://launchpadlibrarian.net/86095234/buildlog_ubuntu-precise-armel.libv8_3.4.14.21-5_FAILEDTOBUILD.txt.gz

[James Page (james-page)]

I think that this is related to http://code.google.com/p/v8/issues/detail?id=590

Ubuntu support armv7 + and by default compiles with thumb2 support; as a result I think that -mno-thumb-interwork, in debian/rules causes a problem on Ubuntu which does not happen in Debian.

[kapouer (kapouer)]

With the move to gyp builds, debian libv8 >= 3.5 will probably break again what's done here and now.
Is there a way to know that arch is armv7 when built within ubuntu ?
In debian we know that by checking DEB_HOST_ARCH == armhf and setting appropriate flags (in debian/rules)

[James Page (james-page)]

@kapouer

We could make the check to set the -mno-thumb-interwork flag on armel conditional on distribution i.e. use "dpkg-vendor --derives-from ubuntu" to determine whether to use -mno-thumb-interwork or -mthumb-interwork.

[kapouer (kapouer)]

On debian i have :
http://wiki.debian.org/ArmHardFloatPort
"Currently the Debian armhf port requires at least an ARMv7 CPU with Thumb-2 and VFP3D16."

Where can i find similar information for ubuntu ?
Besides thumb, there is also vfpv3 support that is better set in debian/rules than detected by v8 build system.

[James Page (james-page)]

@kapouer - https://wiki.ubuntu.com/ARM provides information about ARM on Ubuntu.

[James Page (james-page)]

So I've rebuilt for Ubuntu with:

 -mthumb-interwork (default)
 v8armeabi := softfp (instead of soft) to enable VFP
 unalignedaccess=on (default)

Builds OK; however I get a random set of test fail/CRASH during testing.

Might be related to the hardware I'm using; looking into this further.

[James Page (james-page)]

So the test failures look like problems with my local hardware; testing on one of the Ubuntu porter boxes went fine.

I'll re-test on the second porter box before uploading.

[kapouer (kapouer)]

OK,
as i said, libv8 3.5 will build using gyp : options have changed,
so it may be good to investigate now ? I could even add a condition
in debian/rules so you don't have to change it ?

Here are the actual debian/rules part involved (you can see the whole
at the package's git repo master branch) :

ifeq (armhf, $(DEB_HOST_ARCH))
CXXFLAGS += -fno-tree-sink
CXXFLAGS += -Wno-psabi
# enable armv7 vfpv3
GYPFLAGS += -Darmv7=1 -Darm_fpu=vfpv3 -Darm_neon=0 -Dv8_use_arm_eabi_hardfloat=true
endif

ifeq (armel, $(DEB_HOST_ARCH))
DEB_MAKE_EXTRA_ARGS += vfp3=off
CXXFLAGS += -fno-tree-sink
CXXFLAGS += -Wno-psabi
# Disable thumb-interworking because v8 supports it only on >= armv5t.
# http://code.google.com/p/v8/issues/detail?id=590
CXXFLAGS += -mno-thumb-interwork
# disable armv7, use softfloat
GYPFLAGS += -Darmv7=0 -Dv8_can_use_unaligned_accesses=false -Dv8_use_arm_eabi_hardfloat=false
endif

Jérémy.

[James Page (james-page)]

Built on the panda porter as well; guess my pandaboard must not be working quite right

[James Page (james-page)]

Hi Jérémy

Adding some rules in the Debian packaging to cope with the Ubuntu minimum target and features for armel would be great (no delta!); Looking at the 3.4 packaging I think this should be pretty easy to work into debian/rules:

ifeq (armhf, $(DEB_HOST_ARCH))
CXXFLAGS += -fno-tree-sink
CXXFLAGS += -Wno-psabi
# enable armv7 vfpv3
GYPFLAGS += -Darmv7=1 -Darm_fpu=vfpv3 -Darm_neon=0 -Dv8_use_arm_eabi_hardfloat=true
endif

ifeq (armel, $(DEB_HOST_ARCH))
CXXFLAGS += -fno-tree-sink
CXXFLAGS += -Wno-psabi
ifeq ($(shell dpkg-vendor --is ubuntu && echo true),true)
# Ubuntu targets armv7+ with VFP and thumb2 support by default for armel
GYPFLAGS += -Darmv7=1 -Darm_fpu=vfpv3 -Dv8_use_arm_eabi_hardfloat=false
else
DEB_MAKE_EXTRA_ARGS += vfp3=off
# Disable thumb-interworking because v8 supports it only on >= armv5t.
# http://code.google.com/p/v8/issues/detail?id=590
CXXFLAGS += -mno-thumb-interwork
# disable armv7, use softfloat
GYPFLAGS += -Darmv7=0 -Dv8_can_use_unaligned_accesses=false -Dv8_use_arm_eabi_hardfloat=false
endif
endif

I've not tested the above but I think it should broadly work (I think I've mimiced this in the 3.4 package to resolve the current FTBFS); happy to give it a test with the 3.5 package in the next few days on Ubuntu precise to see if it works OK.

Cheers

James

[James Page (james-page)]

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Hash: SHA256

Hi Jérémy

On 02/12/11 22:03, Jérémy Lal wrote:
> Anyway the default value for arm_neon = 0, but it must be specified
> when armv7=1, because v8 upstream is setting non-overridable
> default values that debian had to override. Do you think it should
> be arm_neon = 0 or 1 ?

If libv8 supports runtime detection of neon extensions then we should
enabled this option; if not then it should be disabled at compile time
as not all platforms targeted by Ubuntu and Debian support this extension.

Cheers

James

- --
James Page
Ubuntu Core Developer
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[Launchpad Janitor (janitor)]

This bug was fixed in the package libv8 - 3.4.14.21-5ubuntu1

---------------
libv8 (3.4.14.21-5ubuntu1) precise; urgency=low

  * Resolve FTBFS on Ubuntu armel (LP: #898558):
    - d/rules: Update rules for armel to support armv7+ with VFP and
      thumb2 enabled by default for Ubuntu.
 -- James Page <email address hidden> Mon, 05 Dec 2011 09:05:31 +0000

[James Page (james-page)]

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Hash: SHA256

On 05/12/11 09:49, Jérémy Lal wrote:
> libv8 is designed to detect all these things at runtime, however,
> we currently build it *with* snapshot, meaning the snapshot must be
> built with the greatest common features. We end up with these three
> archs and setups : debian armel : armv4t, thumb-interworking, soft
> float. But thumb-interworking needs BLX, only supported on armv5,
> so it is disabled. ubuntu armel : armv7, vfpv3 but soft float,
> arm_neon=0 debian armhf : armv7, vfpv3 with hard float (hence the
> name of the port), arm_neon=0

Ubuntu are in the process for bootstrapping armhf for precise; I think
the armhf settings for Debian will transfer OK to Ubuntu.

> I'll include your debian/rules fix for ubuntu in the next release.

Great - thats really helpful! If you want me to give it a test pls
let me know.

Thanks for your help in resolving this!

James

- --
James Page
Ubuntu Core Developer
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