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(maybe) libffi problem for armhf - help needed!

Hey folks,

I should have sent this out earlier, but vacation and other stuff
interrupted... :-(

I had a chat a couple of weeks ago with Marcus Shawcroft, one of the
toolchain experts at ARM, and he's worried that programs/libraries
using libffi on armhf are going to have problems. libffi didn't really
support variadic functions until recently, and the armhf ABI is
*interesting* in this area. See [1] for an ffi mailing list post with
more information, dating back to last year. This is the first time
I've really been aware of this as an issue, and it could mean we need
to work on things quickly. There's a link in that mail to a Linaro
wiki page listing packages that use libffi5 [1]. Looking at the
current state in unstable, I see:

tack:~$ apt-cache rdepends libffi5 | grep '^  ' | wc -l
tack:~$ apt-cache rdepends libffi5 | grep '^  ' | grep -e ghc -e haskell | wc -l

which means that there's a lot of haskell packages to worry about, and
up to ~140 other places to check. The changes for libffi (including an
extra API call to fix this) went in to unstable back in August 2011 in
3.0.10~rc10-1, but packages *using* libffi would need updating to
actually use this new API where necessary.

I think we need to check all those users, to find:

 (a) they're safe (i.e. they don't use variadics with floating point)
 (b) they need updating to use the new libffi API

I've put a list up in the Debian wiki at [3] to help track
this. Please dive in and look at how these packages are using FFI!

[1] http://permalink.gmane.org/gmane.comp.lib.ffi.general/277
[2] https://wiki.linaro.org/WorkingGroups/ToolChain/FFIusers
[3] http://wiki.debian.org/ArmHardFloatTodo#libffi

Steve McIntyre, Cambridge, UK.                                steve@einval.com
< sladen> I actually stayed in a hotel and arrived to find a post-it
          note stuck to the mini-bar saying "Paul: This fridge and
          fittings are the correct way around and do not need altering"

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