linux-kernel - Re: [PATCH v1 4/5] powerpc: Remove cpu-as-y completely

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Date: Fri, 16 Feb 2024 15:25:22 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, Nicholas
 Piggin <npiggin@...il.com>, "jbglaw@...-owl.de" <jbglaw@...-owl.de>
Subject: Re: [PATCH v1 4/5] powerpc: Remove cpu-as-y completely



Le 20/02/2023 à 07:00, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@...roup.eu> writes:
>> cpu-as-y is there to force assembler building options.
>> But there is no need for that. Gcc is passed the necessary
>> options and it automatically pass the appropriate option to
>> GAS.
>>
>> GCC is given -maltivec when relevant, so no need
>> for -Wa,-maltivec in addition
>>
>> And -Wa,-many is wrong as it will hide innapropriate
>> instructions. Better to detect them and handle them on a
>> case by case basis.
>> -Wa,-many was added by commit 960e30029863 ("powerpc/Makefile:
>> Fix PPC_BOOK3S_64 ASFLAGS") in order to fix an issue with
>> clang and the passed -Wa,-mpower4 option. But we have now
>> removed it expecting the compiler to automatically pass the
>> proper options and instructions based on -mcpu=power4
> 
> I wanted to apply this one, but it caused a lot of breakage for big
> endian Book3S-64 builds - where we build for power4 but have lots of
> code that uses >= power5 instructions.
> 
> I'll try and get those all fixed and pick this up for the next merge
> window.
> 

ping ?