Re: [meta-oe][meta-filesystems][PATCH 1/2] libimobiledevice: remove runtime configure check

["S. Lockwood-Childs" <sjl@vctlabs.com>]

Apologies for managing to reply to the wrong thread the first time...

On Sat, Aug 08, 2015 at 04:01:38PM -0700, Khem Raj wrote:
> 
> > On Jul 17, 2015, at 5:38 PM, S. Lockwood-Childs <sjl@vctlabs.com> wrote:
> > 
> > configure.ac had a runtime check for large file support that got run
> > on 64-bit architectures, and all runtime checks must go away to be
> > cross-compile safe.
> > 
> > Luckily that runtime check was extraneous, so just remove it;
> > standard AC_SYS_LARGEFILE macro should be sufficient for figuring out
> > proper settings to get large file support.
> > 
> > Also un-blacklist libimobiledevice, since this problem was the
> > reason for the blacklist.
> > 
> 
> one difference is that now it will depend on --enable-largefile secondly, what does AC_SYS_LARGEFILE
> check do in the end ? is it a link time check ?

Not sure what you mean by 'now it will depend on --enable-largefile' since 
the handling of that flag isn't being changed. I didn't add AC_SYS_LARGEFILE
macro; it was already there. The recipe still doesn't need to set that flag...
large file support should get enabled if the platform supports it.

AC_SYS_LARGEFILE does a compile-time check that off_t is large as expected,
and if not it tries some defines (such as _FILE_OFFSET_BITS) to see if they
can make off_t check pass. In the 64-bit Linux case, the first check passes,
since no tinkering with extra defines is needed, but for 32-bit case 
_FILE_OFFSET_BITS will get defined.