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On Wed, 5 Aug 2009, Ingo Molnar wrote:
> * Dave Airlie <airlied@gmail.com> wrote:
>
> > Hey,
> >
> > So I spent 3-4 hrs today (I'm stupid yes) tracking down a .o
> > breakage by blaming rawhide gcc/binutils as I was using make
> > V=1and seeing only the compiler chain running,
>
> Hm, is this that powerpc related build bug you just reported?
Well we tracked it down and it is powerpc64 specific.
Seems that in drivers/hwmon/lm93.c there's a function called:
LM93_IN_FROM_REG()
But PPC64 has function descriptors and the real function names (the ones
you see in objdump) start with a '.'. Thus this in objdump you have:
Disassembly of section .text:
0000000000000000 <.LM93_IN_FROM_REG>:
0: 7c 08 02 a6 mflr r0
4: fb 81 ff e0 std r28,-32(r1)
The function name used is .LM93_IN_FROM_REG. But gcc considers symbols
that start with ".L" as a special symbol that is used inside the assembly
stage.
The nm passed into recordmcount uses the --synthetic option which shows
the ".L" symbols (my runs outside of the build did not include the
--synthetic option, so my older patch worked). We see the function as a
local.
Now to capture all the locations that use "mcount" we need to have a
reference to link into the object file a list of mcount callers. We need a
reference that will not disappear. We try to use a global function and if
that does not work, we use a local function as a reference. But to relink
the section back into the object, we need to make it global. In this case,
we run objcopy using --globalize-symbol and --localize-symbol to convert
the symbol into a global symbol, link the mcount list, then convert it
back to a local symbol.
This works great except for this case. .L* symbols can not be converted
into a global symbol, and the mcount section referencing it will remain
unresolved.
Reported-by: Dave Airlie <airlied@gmail.com>
LKML-Reference: <alpine.DEB.2.00.0908052011590.5010@gandalf.stny.rr.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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| .. | ||
| basic | ||
| dtc | ||
| genksyms | ||
| kconfig | ||
| ksymoops | ||
| mod | ||
| package | ||
| rt-tester | ||
| selinux | ||
| tracing | ||
| .gitignore | ||
| bin2c.c | ||
| binoffset.c | ||
| bloat-o-meter | ||
| bootgraph.pl | ||
| checkincludes.pl | ||
| checkkconfigsymbols.sh | ||
| checkpatch.pl | ||
| checkstack.pl | ||
| checksyscalls.sh | ||
| checkversion.pl | ||
| cleanfile | ||
| cleanpatch | ||
| config | ||
| conmakehash.c | ||
| decodecode | ||
| diffconfig | ||
| export_report.pl | ||
| extract-ikconfig | ||
| gcc-version.sh | ||
| gcc-x86_32-has-stack-protector.sh | ||
| gcc-x86_64-has-stack-protector.sh | ||
| gen_initramfs_list.sh | ||
| get_maintainer.pl | ||
| gfp-translate | ||
| headerdep.pl | ||
| headers.sh | ||
| headers_check.pl | ||
| headers_install.pl | ||
| kallsyms.c | ||
| Kbuild.include | ||
| kernel-doc | ||
| Lindent | ||
| Makefile | ||
| Makefile.build | ||
| Makefile.clean | ||
| Makefile.fwinst | ||
| Makefile.headersinst | ||
| Makefile.host | ||
| Makefile.lib | ||
| Makefile.modinst | ||
| Makefile.modpost | ||
| makelst | ||
| markup_oops.pl | ||
| mkcompile_h | ||
| mkmakefile | ||
| mksysmap | ||
| mkuboot.sh | ||
| mkversion | ||
| namespace.pl | ||
| patch-kernel | ||
| pnmtologo.c | ||
| profile2linkerlist.pl | ||
| recordmcount.pl | ||
| setlocalversion | ||
| show_delta | ||
| tags.sh | ||
| unifdef.c | ||
| ver_linux | ||