Re: linux-2.6_2.6.24~rc8-1~experimental.2~snapshot.10147 FTBFS on mips

[Ralf Baechle <ralf@linux-mips.org>]

On Thu, Jan 24, 2008 at 09:38:10PM +0100, Martin Michlmayr wrote:

> * Florian Lohoff <flo@rfc822.org> [2008-01-21 15:00]:
> > linux-2.6 version linux-2.6_2.6.24~rc8-1~experimental.2~snapshot.10147
> > FTBFS on mips:
> >   CC [M]  drivers/net/niu.o
> > {standard input}: Assembler messages:
> > {standard input}:293: Error: Branch out of range
> > make[6]: *** [drivers/net/niu.o] Error 1
> 
> I believe this is actually a kernel bug.  Looking at the preprocessed
> source, I see that it contains some inline assembler:
> 
>   __asm__ __volatile__(
>   "     .set    mips3                                   \n"
>   "1:   " "ll   " "%0, %1                       # set_bit       \n"
>   "     or      %0, %2                                  \n"
>   "     " "sc   " "%0, %1                                       \n"
>   "     beqz    %0, 2f                                  \n"
>   "     .subsection 2                                   \n"
>   "2:   b       1b                                      \n"
>   "     .previous                                       \n"
> 
> And the "Branch out of range" error is in that piece of code.
> Ralf/Aurelien, can you please take a look.  A kernel config is
> attached.

Known problem.  It happens to hit because the niu driver is a single
extremly large file resulting in the max. branch range of +/- 128k
getting exceeded.  Easily curable but that'd come at a performance price.
Since atm this only affects a driver which probably nobody is using
on MIPS anyway I'm hesitating.

  Ralf