[yocto] libm implementation issue

[peterengcomau001 at adam.com.au]

 Hi Richard,I am using the standard poky DISTRO (although the
configuration is DISTRO ?= "poky' so something else my be changing
it. Also The final image is pretty large taking 256Mb.Is there
anything else I can check that may be altering the DISTRO or the
libc. If I look at all the setting in ECLIPSE, there is no reference
to changing any libm or -lm settings.
I am also having problems with some of the libraries being generated
when i use qemu-extra-sdk are not present in the resulting rootfs, so
I have to also run "$bitbake image -c populate_sdk" and manully copy
over the affected libraries. However, since I use eglibc-static in
the extra image features in the config file, I have not had a problem
with missing libc libraries according to the linker, but that doesn't
mean there is not something else wrong.

Also, I have been trying to access the jiffy.h which should be
standard in Linux but is not created as part of the build. It is
created during the build but something is removing it from the image
(or not including it). Do you have any idea what I can do to add
jiffy to the final image?
Thanks for your help.
Lachlan

----- Original Message -----
From: "Richard Purdie" 
To:
Cc:
Sent:Wed, 31 Dec 2014 09:41:33 +0000
Subject:Re: [yocto] libm implementation issue

 On Tue, 2014-12-30 at 20:09 +1030, peterengcomau001 at adam.com.au
wrote:
 > 
 > I have some software that uses specific mathematical functions.
When I
 > attempt to compile them with the Yocto cross-compile tools, the
 > functions are not recognised. E.g. 'pow' in 
 > According to website
https://wiki.yoctoproject.org/wiki/Minimal_Image,
 > not all eglibc features are installed as standard, and that I
should
 > alter my local.conf file. I have added the following:
 > 
 > DISTRO_FEATURES_LIBC += " libc-libm "
 > DISTRO_FEATURES_append = " ${DISTRO_FEATURES_LIBC} "

 By default the libc we build is fully featured. The only time we cut
 down the libc by default is when you use DISTRO = "poky-tiny". Are
you
 using poky-tiny?

 If you're not, the most likely issue you didn't see pow and friends
 would be a missing linkage against libm (-lm on the commandline for
 gcc/ld).

 Cheers,

 Richard

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