Re: [RFC PATCH v3] MIPS: fix build with binutils 2.24.51+

[Markos Chandras <Markos.Chandras@imgtec.com>]

On 10/11/2014 11:09 AM, Manuel Lauss wrote:
> Starting with version 2.24.51.20140728 MIPS binutils complain loudly
> about mixing soft-float and hard-float object files, leading to this
> build failure since GCC is invoked with "-msoft-float" on MIPS:
> 
> {standard input}: Warning: .gnu_attribute 4,3 requires `softfloat'
>   LD      arch/mips/alchemy/common/built-in.o
> mipsel-softfloat-linux-gnu-ld: Warning: arch/mips/alchemy/common/built-in.o
>  uses -msoft-float (set by arch/mips/alchemy/common/prom.o),
>  arch/mips/alchemy/common/sleeper.o uses -mhard-float
> 
> To fix this, we detect if GAS is new enough to support "-msoft-float" command
> option, and if it does, we can let GCC pass it to GAS;  but then we also need
> to sprinkle the files which make use of floating point registers with the
> necessary ".set hardfloat" directives.
> 
> Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
> ---
> I've only tested a mips32r1 build, but at least binutils-2.23 and a
> snapshot from today (with the MIPS fp changes) compile a bootable
> kernel.
> 
> Tests on 64bit and with MSA and other extensions also appreciated!
> 
> v3: incorporate Maciej's suggestions:
> 	- detect if gas can handle -msoft-float and ".set hardfloat"
> 	- apply .set hardfloat only where really necessary
> 
> v2: cover more files
> 
> This was introduced in binutils commit  351cdf24d223290b15fa991e5052ec9e9bd1e284
> ("[MIPS] Implement O32 FPXX, FP64 and FP64A ABI extensions").
> 
>  arch/mips/Makefile                  |  9 +++++++++
>  arch/mips/include/asm/asmmacro-32.h |  5 +++++
>  arch/mips/include/asm/asmmacro.h    | 18 ++++++++++++++++++
>  arch/mips/include/asm/fpregdef.h    | 14 ++++++++++++++
>  arch/mips/include/asm/mipsregs.h    | 19 +++++++++++++++++++
>  arch/mips/kernel/genex.S            |  1 +
>  arch/mips/kernel/r2300_switch.S     |  5 +++++
>  arch/mips/kernel/r4k_fpu.S          |  7 +++++++
>  arch/mips/kernel/r4k_switch.S       |  9 +++++++++
>  arch/mips/kernel/r6000_fpu.S        |  5 +++++
>  10 files changed, 92 insertions(+)
> 
Hi,

I applied this patch but it still does not build for me on a
malta_defconfig:

arch/mips/kernel/r4k_fpu.S: Assembler messages:
arch/mips/kernel/r4k_fpu.S:52: Error: float register should be even, was 1
arch/mips/kernel/r4k_fpu.S:53: Error: float register should be even, was 3
arch/mips/kernel/r4k_fpu.S:54: Error: float register should be even, was 5
arch/mips/kernel/r4k_fpu.S:55: Error: float register should be even, was 7
...

The error is different this time so we probably need a follow-up patch

-- 
markos