Build regression introduced by 31cdd0c39c7544ced79da53aa0b7e989f3a39582

[Michael Ellerman]

Paul Mackerras <paulus at ozlabs.org> writes:

> On Tue, Sep 06, 2016 at 11:01:02PM +0200, John Paul Adrian Glaubitz wrote:
>> Hi Paul!
>> 
>> I'm referring to your change [1]:
>> 
>> "powerpc/xmon: Fix SPR read/write commands and add command to dump SPRs"
>> 
>> which introduced assembly code in the new file arch/powerpc/xmon/spr_access.S.
>> 
>> Unfortunately, this code contains assembly instructions which are not available on
>> all ppc targets. In particular, this change breaks the build on PPC e500v2 targets,
>> see the corresponding Debian bug report [2].
>> 
>> Could you have a look and possibly add some guarding #ifdefs for the ppc targets
>> where "ld" is not a supported instruction?
>
> I blame Michael. :)  My original version of the patch didn't have the
> ld instructions, and then Michael did a v2 that was different.  He
> didn't update the patch description so I don't know exactly why he
> changed that.  I'll discuss it with him.

Yep my fault. I changed the code to load the address of the SPR table
from the TOC, and just used ld without thinking.

Interestingly it builds fine for me, even for 32-bit configs, I assume
because my toolchains are 32/64-bit they are able to cope with it. I'll
try and built a 32-bit only toolchain to catch these problems in future.

cheers