Re: Fix PR 2698

[Andrew Cagney <cagney at redhat dot com>]

Yao Qi wrote:
> On Mon, May 29, 2006 at 10:33:18AM -0400, Andrew Cagney wrote:
>   
> > Yao Qi wrote:
> >     
> > > This patch fixes PR2698, where frysk could not be built on ppc64,
> > > since libopcode not could find 'bfd_getb32' and 'bfd_getl32'.
> > >
> > > libopcodes has some external functions that are provided by libbfd on
> > > ppc64,
> > > [qiyao@plinuxt18 build-frysk-qiyao]$ readelf -s 
> > > /usr/lib64/libopcodes-2.16.91.0.6.so | grep bfd
> > >    90: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND bfd_get_arch
> > >   100: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND bfd_getb32
> > >   122: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND bfd_getl32
> > >   127: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND bfd_get_mach
> > >  
> > >       
> > Rather than drag in bfd, would it be possible to stub these methods?
> >     
> Luckily, 'bfd_getb32' and 'bfd_getl32' in bfd/libbfd.c are simple.  I
> only copy the definition of these two functions to 
> frysk/frysk-imports/util/elf/libbfd_get.c, compile it to a shared object,
> and linked the shared object with fryski as follows,
>
> [qiyao@plinuxt18 frysk-imports]$ gcc -m64
> ../../frysk/frysk-imports/util/elf/libbfd_get.c -c -o libbfd_get.o
> [qiyao@plinuxt18 frysk-imports]$ gcc -m64 -g -O libbfd_get.o -shared -o
> libbfd_get.so 
> [qiyao@plinuxt18 frysk-imports]$ gcj -m64
> -I../../frysk/frysk-imports -I. -Ijargs.jar -Ijunit.jar -Werror -Wall -fPIC
> -g -O -o fryski -lgij -Wl,-rpath,./:/home/qiyao/build-frysk-5-23/frysk-imports
> -L./ -lfrysk-imports       -L./ -lfrysk-jargs       -L./ -lfrysk-junit
> -Lelfutils/libelf/ -lelf       -Lelfutils/libdw/ -ldw
> -Lelfutils/libdwfl/ -ldwfl      -lopcodes     libfrysk-imports.so
> libfrysk-jargs.so  libfrysk-junit.so libfrysk-imports.a libfrysk-jargs.a
> libfrysk-junit.a elfutils/libelf/libelf.a elfutils/libdw/libdw.a
> elfutils/libdwfl/libdwfl.a -lopcodes -L. -lbfd_get
>                                      ^^^^^^^^^^^^^
>
> I tried this both on i386 and ppc64, and errors are removed.  Here is
> libbfd_get.c fro your reference,
>
> unsigned long 
> bfd_getb32 (const void *p) 
> { 
>   const char *addr = p;
>   unsigned long v;
>   v = (unsigned long) addr[0] << 24;
>   v |= (unsigned long) addr[1] << 16;
>   v |= (unsigned long) addr[2] << 8;
>   v |= (unsigned long) addr[3];
>   return v;
> }
> unsigned long
> bfd_getl32 (const void *p)
> {
>   const char *addr = p;
>   unsigned long v;
>   v = (unsigned long) addr[0];
>   v |= (unsigned long) addr[1] << 8;
>   v |= (unsigned long) addr[2] << 16;
>   v |= (unsigned long) addr[3] << 24;
>   return v;
> }
>
> Actually, I am not sure whether we could solve the problem in this way
> or not.  In a long run, if the functionality of libopcode could be 
> integrated into ElfUtils, frysk do not need to be linked with
> libopcode.  That would be better!
>   
Definitely agree, we can think of the use of opcodes as an interim solution.
> Any comments on this?  Thanks in advance!
>
>   
I'll integrate something equivalent.

Thanks!

Andrew