Re: Make Stap compatible with Android

[Torsten Polle <Torsten dot Polle at gmx dot de>]

> Am 14.05.2018 um 22:56 schrieb Mark Wielaard <mark@klomp.org>:
> 
> On Mon, May 14, 2018 at 09:06:09PM +0200, Alexander Lochmann wrote:
>> 
>>>> On my opinion, this does far beyond what someone should when compiling
>>>> stap{io,run} for Android.
>>> 
>>> I hear you, but your patches went to a fair amount of trouble to work
>>> around the lack of elfutils, when elfutils has android support (if I'm
>>> reading its source correctly). This does seem like the right way to
>>> go.
>>> 
>> Okay. Android does built its own version of elfutils, and their compiler
>> seems to support libz. Sorry for that.
>> However, the Android libc (aka bionic) lags some standard features,
>> i.e., argparse. To overcome that issue, the Android developers made some
>> fixups:
>> https://android.googlesource.com/platform/external/elfutils.git/+/master/bionic-fixup/
>> 
>> Android uses its own build system which bypasses configure in case of
>> elfutils. The Android build system is used to include the aforementioned
>> fixups:
>> https://android.googlesource.com/platform/external/elfutils.git/+/master/libelf/Android.bp
>> (Android.bp is a new variant of a Makefile)
>> 
>> One of those fixups is a workaround for the missing argp_parse in bionic.
>> I tried to include that fixup manually: ./configure
>> --host=arm-linux-androideabi  CFLAGS="-include
>> `pwd`/bionic-fixup/AndroidFixup.h -I`pwd`/bionic-fixup/"
>> But configure still fails, because the linker cannot find -largp.
> 
> I don't understand precisely what you are trying to do.
> But I get the impression that you only want/need the runtime
> (stapio, staprun) on android. In that case the existing elfutils
> libelf support should be all you need and you don't need to
> build elfutils from scratch. You only need that if you want to
> build the other parts of systemtap (which uses the elfutils libdw
> library, which doesn't seem available on android out of the box yet.
> 
> Cheers,
> Mark

Hi Alexander,

I’m using SystemTap for a variety of systems all of which are used with a host and target (cross-compile). On the targets I’m only using staprun/stapio. One of those targets is so rudimentary that I cannot compile elfutils. I use a simply patch to do so. If you’re interested, I could share the patch.

Kind Regards,
Torsten