Re: [PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

From: Guenter Roeck
Date: Wed Aug 26 2020 - 17:06:43 EST


Hi,

On Wed, Oct 16, 2019 at 02:51:17PM -0700, Greg Kroah-Hartman wrote:
> From: Paul Burton <paul.burton@xxxxxxxx>
>
> commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.
>
> GCC 9.x automatically enables support for Loongson MMI instructions when
> using some -march= flags, and then errors out when -msoft-float is
> specified with:
>
> cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’
>
> The kernel shouldn't be using these MMI instructions anyway, just as it
> doesn't use floating point instructions. Explicitly disable them in
> order to fix the build with GCC 9.x.
>

I still see this problem when trying to compile fuloong2e_defconfig with
gcc 9.x or later. Reason seems to be that the patch was applied to
arch/mips/loongson64/Platform, but fuloong2e_defconfig uses
arch/mips/loongson2ef/Platform.

Am I missing something ?

Thanks,
Guenter