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    SubjectRe: ftrace scripts and make V=1

    On Wed, 5 Aug 2009, Ingo Molnar wrote:

    > * Dave Airlie <> 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:


    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

    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

    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

    Try this patch and see if it fixes your issue.


    -- Steve

    diff --git a/scripts/ b/scripts/
    index d29baa2..4889c44 100755
    --- a/scripts/
    +++ b/scripts/
    @@ -414,7 +414,10 @@ while (<IN>) {
    $offset = hex $1;
    } else {
    # if we already have a function, and this is weak, skip it
    - if (!defined($ref_func) && !defined($weak{$text})) {
    + if (!defined($ref_func) && !defined($weak{$text}) &&
    + # PPC64 can have symbols that start with .L and
    + # gcc considers these special. Don't use them!
    + $text !~ /^\.L/) {
    $ref_func = $text;
    $offset = hex $1;

     \ /
      Last update: 2009-08-06 04:03    [W:0.022 / U:62.228 seconds]
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