linux-kernel - Re: [PATCH 2/3] powerpc: fix build errors

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Message-ID: <20220224171207.GM614@gate.crashing.org>
Date:   Thu, 24 Feb 2022 11:12:07 -0600
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Nicholas Piggin <npiggin@...il.com>
Cc:     Anders Roxell <anders.roxell@...aro.org>, mpe@...erman.id.au,
        stable@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 2/3] powerpc: fix build errors

On Thu, Feb 24, 2022 at 03:05:28PM +1000, Nicholas Piggin wrote:
> + * gcc 10 started to emit a .machine directive at the beginning of generated
> + * .s files, which overrides assembler -Wa,-m<cpu> options passed down.
> + * Unclear if this behaviour will be reverted.

It will not be reverted.  If you need a certain .machine for some asm
code, you should write just that!

> +#ifdef CONFIG_CC_IS_GCC
> +#if (GCC_VERSION >= 100000)
> +#if (CONFIG_AS_VERSION == 23800)
> +asm(".machine any");
> +#endif
> +#endif
> +#endif
> +#endif /* __ASSEMBLY__ */

Abusing toplevel asm like this is broken and you *will* end up with
unhappiness all around.


Segher