Re: [PATCH] Ensure that MIPS target code is compiled for the O32 ABI.

[Mark H Weaver <mhw@netris.org>]

Andrei Borzenkov <arvidjaar@gmail.com> writes:

> 19.08.2015 21:35, Mark H Weaver пишет:
>> Include -mabi=32 in CFLAGS_PLATFORM and CCASFLAGS_PLATFORM to compile
>> code for the O32 ABI when targetting MIPS, since the MIPS assembly code
>> in GRUB assumes this.  This flag is also needed when compiling
>> asm-tests/mips.S from configure, because GNU as rejects MIPS register
>> names such as $t2 unless the O32 ABI is selected.
>> ---
>>   conf/Makefile.common | 4 ++++
>>   configure.ac         | 7 +++++--
>>   2 files changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/conf/Makefile.common b/conf/Makefile.common
>> index fcb8d2e..bd125da 100644
>> --- a/conf/Makefile.common
>> +++ b/conf/Makefile.common
>> @@ -20,6 +20,10 @@ endif
>>   if COND_powerpc_ieee1275
>>     CFLAGS_PLATFORM += -mcpu=powerpc
>>   endif
>> +if COND_mips
>> +  CFLAGS_PLATFORM += -mabi=32
>> +  CCASFLAGS_PLATFORM = -mabi=32
>> +endif
>>
>
> Does it work with clang?

Based on the error message below, clang seems to accept and understand
the -mabi=32 option, but the version of clang that we have in GNU Guix
(which uses the N32 ABI on MIPS) seems to lack support for compiling for
O32:

  mhw@librenote:~$ clang -mabi=32 mips.S 
  error: unknown target CPU 'mips32r2'

However, it doesn't work without that option either:

  mhw@librenote:~$ clang mips.S 
  mips.S: Assembler messages:
  mips.S:7: Error: invalid operands `ld $t2,0($t6)'
  mips.S:10: Error: invalid operands `addiu $t7,$s0,(b-a)'
  clang-3.6: error: assembler command failed with exit code 1 (use -v to see invocation)

This is the same failure that occurs with gcc when configured to use the
N32 ABI by default.  I also tried passing -fno-integrated-as in both
cases above, but it made no difference.

      Mark