linux-kernel - Re: [PATCH] selftests: riscv: fix v_exec_initval

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Message-ID: <f3bde84d-b53e-4b81-b995-3b81d614b789@iencinas.com>
Date: Thu, 6 Mar 2025 07:31:22 +0100
From: Ignacio Encinas Rubio <ignacio@...cinas.com>
To: Charlie Jenkins <charlie@...osinc.com>
Cc: linux-kernel-mentees@...ts.linux.dev, skhan@...uxfoundation.org,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Alexandre Ghiti <alex@...ti.fr>,
 linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests: riscv: fix v_exec_initval_nolibc.c



On 5/3/25 22:49, Charlie Jenkins wrote:
> On Wed, Mar 05, 2025 at 05:39:28PM +0100, Ignacio Encinas wrote:
>> Vector registers are zero initialized by the kernel. Stop accepting
>> "all ones" as a clean value.
>>
>> Note that this was not working as expected given that
>> 	value == 0xff
>> can be assumed to be always false by the compiler as value's range is
>> [-128, 127]. Both GCC (-Wtype-limits) and clang
>> (-Wtautological-constant-out-of-range-compare) warn about this.
> 
> This check was included because the "dirty" value is an implementation
> detail that I believe is not strongly defined in the ABI. Since linux
> does always set this value to zero (currently) we can safely remove this
> check. 

Thanks for the review. Just after sending the patch I noticed it should
also remove some code that becomes useless after this change: 
_prev_value_ and _first_ variables were only needed because two "clean" 
values were supported.

I'll send a v2 tomorrow. I'm guessing keeping your "Reviewed-by" and
"Tested-by" is the appropriate thing to do as the changes are very
simple. Let me know if that's not the case.

Thanks again!