On 09/05/2014 03:36 PM, Gary Robertson wrote:
Dear OE developers,
Linaro Networking Group is building root filesystem images containing
the LTP test suite, using the current recipe at
openembedded-core/meta/recipes-extended/ltp/ltp_20140422.bb
<http://ltp_20140422.bb>. This build uses autoconf to probe mutex
feature support for protocol specification, priority inheritance, and
robust mutexes. The macros used for this can be found in
ltp/testcases/realtime/m4/check.m4 from the LTP git repository.
We are cross-building for the armv7a architecture using the machine
definition found in
meta-linaro/meta-linaro/conf/machine/genericarmv7a.conf. The
development host platform is an Ubuntu 12.04 x86_64 platform with all
software kept regularly updated from the Ubuntu repositories.
The macros in check.m4 use the AC_TRY_COMPILE function macro to
attempt compilation of POSIX function calls utilizing the features
being probed - such that if the compilation fails the features are
deemed to be unsupported... and if compilation succeeds the features
are deemed supported.
Native compilation of the same code used in the probes, and execution
of the resulting program - shows support for all the probed mutex
features on both the development host as well as the armv7a target
platform... that is when this probe code is built on either the host
or target machine and then executed in that environment... so support
is there in both environments.
Despite the presence of this support the AC_TRY_COMPILE macro is
indicating a lack of support for the probed features during the
cross-build process.
I am not personally familiar with the detailed function of the
autoconf macros, and I can find no documentation about how OE
interacts with those macros in order to coerce them into configuring
for the target machine in a cross-build environment... so I am hoping
the autoconf experts at OE can shed some light on this and at least
provide some clues as to where to look for the problem and possible
resolution. Any insight you can provide in this matter would be
appreciated.
Any mention of "armv7a" and "mutex" points me to
http://cgit.openembedded.org/openembedded-core/commit/?id=0ba6ab39f187ecd4261f08e768f365f461384a3a
which fixed a problem where the compiler and runtime disagreed about the
capabilities of the target processor unless special flags were passed to
the compiler. Presence of armv7a enables mutex-related instructions
which affect what support is provided in the C runtime system; absence
of armv7 at compile-time will result in attempts to locate alternative
implementations that are not present.
It's possible that a similar issue is hitting you, depending on what
options are present in the test compile and whether the libraries linked
to were built with compatible options.
I tried setting up a meta-linaro + meta-linaro-toolchain build to see if
I could reproduce it, but meta-linaro appears to not be up to date with
the removal of eglibc from oe-core.
The autoconf test should have left information in the config.log file
showing how it tried to build the application. Having that information
would help with diagnosis.
Hope this is some help.
Peter
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