Re: [Xen-devel] ocaml bindings

[Jon Ludlam <jonathan.ludlam@xxxxxxxxxxxxx>]

On 03/04/13 21:33, Andrew Cooper wrote:
> On 03/04/13 21:24, AL13N wrote:
> > Op woensdag 3 april 2013 20:36:51 schreef Andrew Cooper:
> > > On 03/04/13 20:24, AL13N wrote:
> > > > Op woensdag 3 april 2013 20:18:53 schreef AL13N:
> > > > > Op woensdag 3 april 2013 18:12:21 schreef Andrew Cooper:
> > > > > > On 03/04/13 18:03, AL13N wrote:
> > > > > > > i'm the Mageia Xen package maintainer, and a user reported that i had
> > > > > > > missing symbols in my ocaml bindings:
> > > > > > >
> > > > > > > https://bugs.mageia.org/show_bug.cgi?id=5199
> > > > > > >
> > > > > > > i'm using Xen 4.2.1 and ocaml 3.12.1
> > > > > > >
> > > > > > > the problem is that if you just to a simple hello world and you're
> > > > > > > using
> > > > > > > certain bindings (eg: xeneventch): you get missing symbols. (others
> > > > > > > appear
> > > > > > > to be fine).
> > > > > > >
> > > > > > > I know next to nothing about ocaml, and it could be my build process,
> > > > > > > but
> > > > > > > i
> > > > > > > kinda need some help about this.
> > > > > > >
> > > > > > > this is my spec file:
> > > > > > > http://svnweb.mageia.org/packages/cauldron/xen/current
> > > > > > >
> > > > > > > Thanks in advance
> > > > > > >
> > > > > > > PS: we're at version freeze and release freeze is pretty soon :-S
> > > > > > This is because the ocaml tools embed the build target links in the
> > > > > > generated libs.  If you try to link against them later outside the build
> > > > > > environment, it will break.
> > > > > >
> > > > > > Attached is the patch used to fix this problem for XenServer for Xen
> > > > > > 4.2.
> > > > > thanks alot for the very quick help, i'm testing right now...
> > > > it seems the tests definately improve things...
> > > >
> > > > [root@localhost ~]# cat testfile.ml
> > > > print_string "hello"
> > > > [root@localhost ~]# ocamlfind ocamlc -o test -thread -package xeneventchn
> > > > -
> > > > linkpkg -g testfile.ml
> > > > [root@localhost ~]# ./test
> > > > Fatal error: cannot load shared library dllxeneventchn_stubs
> > > > Reason: dllxeneventchn_stubs.so: cannot open shared object file: No such
> > > > file or directory
> > > >
> > > >
> > > > (i have no idea if i need to ./test execute this, or if this is normal
> > > > behavior)
> > > You presumably need tools/ocaml/libs/eventchn/dllxeneventchn_stubs.so on
> > > your load path.  Under my system, would be installed to
> > > /usr/local/lib/ocaml/3.11.2/xeneventchn/dllxeneventchn_stubs.so
> > [root@localhost ~]# ls /usr/lib64/ocaml/xeneventchn/ -lsha
> > total 64K
> >     0 drwxr-xr-x 1 root root  246 Apr  3 19:16 ./
> >     0 drwxr-xr-x 1 root root 7.2K Apr  3 19:02 ../
> > 4.0K -rw-r--r-- 1 root root  150 Apr  3 18:35 META
> >   12K -rwxr-xr-x 1 root root  11K Apr  3 18:40 dllxeneventchn_stubs.so*
> >   24K -rw-r--r-- 1 root root  21K Apr  3 18:35 libxeneventchn_stubs.a
> > 8.0K -rw-r--r-- 1 root root 4.5K Apr  3 18:35 xeneventchn.a
> > 4.0K -rw-r--r-- 1 root root 2.8K Apr  3 18:35 xeneventchn.cma
> > 4.0K -rw-r--r-- 1 root root 1.2K Apr  3 18:35 xeneventchn.cmi
> > 4.0K -rw-r--r-- 1 root root  223 Apr  3 18:35 xeneventchn.cmx
> > 4.0K -rw-r--r-- 1 root root  258 Apr  3 18:35 xeneventchn.cmxa
> >
> > what is this "load path" is this something like LD_LIBRARY_PATH ?
> Unfortunately I am no expert in the workings of Ocaml.  I will have to
> defer to others.  Jon/Dave - any ideas?
>
> ~Andrew
Hmm. We don't actually use the bytecode compiler/toplevel, so there's a 
good chance that the patch doesn't fix them correctly.
Could you please check to see whether it sorts out native code 
compilation for you? Try:
jludlam@humongous:~$ cat test.ml
let _ =
    let open Xenctrl in
    let v = with_intf version in
    Printf.printf "%d.%d%s\n" v.major v.minor v.extra
jludlam@humongous:~$ ocamlfind ocamlopt -o test -thread -package xenctrl 
-linkpkg test.ml
jludlam@humongous:~$ sudo ./test
4.2.1

Meanwhile, I'll investigate to see whether I can repro your problem (my 
ocaml libs are installed slightly differently than usual at the moment).
Jon


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