Hi Alan, On Thu, 5 Jul 2012 19:13:48 +0930 Alan Modra <amodra@xxxxxxxxx> wrote: > > On Thu, Jul 05, 2012 at 06:33:45PM +1000, Stephen Rothwell wrote: > > powerpc64-linux-ld: drivers/built-in.o: In function `.gpiochip_is_requested': > > (.text+0x4): sibling call optimization to `_savegpr0_29' does not allow automatic multiple TOCs; recompile with -mminimal-toc or -fno-optimize-sibling-calls, or make `_savegpr0_29' extern > > > > I got more than 60000 of these messages before I killed the link. :-( I > > am not sure what has changed to do this, but it may have been masked for > > the past few releases due to other linking problems. > > Let me guess. You're using bleeding edge gcc but not binutils. powerpc-linux-gcc (GCC) 4.6.3 GNU ld (GNU Binutils) 2.22 both built from upstream sources (by Tony). > a) Recent gcc has fixed prologue and epilogue generation which now > properly makes use of out-of-line register save and restore > functions when compiling with -Os. > b) Recent ld doesn't emit out-of-line save/restore function for ld -r, > but yours does. You need my 2012-06-22 patch. > c) Kernel uses ld -r for packaging. > > (b) and (c) together mean you get a definition for _savegpr0_29 munged > together with other functions. That's bad. If _savegpr0_29 wasn't > emitted until the final link stage then it would be in a code section > containing just save/restore functions. ld will analyse that section > and notice the absense of toc relocations; functions therein don't > use the toc and can thus be called from any toc group without needing > a toc adjusting stub. In your case _savegpr0_29 is in a section that > has toc relocations (from normal compiled code), so ld decides that > any function in that section must have a proper value for the toc > register. But calls to _savegpr0_29 don't have a following nop to > overwrite with a toc restore insn, hence the ld error. > > Score another black mark for ld -r. OK, the new toolchain may be the problem. I changed from: powerpc-linux-gcc (GCC) 4.6.0 GNU ld (GNU Binutils) 2.21 on June 20 and the current errors may have been masked an early bailout after getting theses errors: powerpc64-linux-ld: arch/powerpc/net/built-in.o: In function `bpf_slow_path_word': (.text+0x90): sibling call optimization to `skb_copy_bits' does not allow automatic multiple TOCs; recompile with -mminimal-toc or -fno-optimize-sibling-calls, or make `skb_copy_bits' extern which have now been fixed. So would a simple patch that puts the _savegpr etc functions in their own section (defined how?) fix this for us? -- Cheers, Stephen Rothwell sfr@xxxxxxxxxxxxxxxx
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