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From:   =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
To:     Vineet Gupta <vineetg@rivosinc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv@lists.infradead.org
Cc:     =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@rivosinc.com>,
        linux-kernel@vger.kernel.org, linux@rivosinc.com,
        Palmer Dabbelt <palmer@rivosinc.com>,
        =?utf-8?Q?R?= =?utf-8?Q?=C3=A9mi?= Denis-Courmont 
        <remi@remlab.net>, Darius Rad <darius@bluespec.com>,
        Andy Chiu <andy.chiu@sifive.com>
Subject: Re: [PATCH] riscv: Discard vector state on syscalls
In-Reply-To: <b990638b-a86a-ee43-f8b1-18a0a0651ad0@rivosinc.com>
References: <20230622173613.30722-1-bjorn@kernel.org>
 <b990638b-a86a-ee43-f8b1-18a0a0651ad0@rivosinc.com>
Date:   Mon, 26 Jun 2023 17:46:57 +0200
Message-ID: <874jmuns3y.fsf@all.your.base.are.belong.to.us>
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Vineet Gupta <vineetg@rivosinc.com> writes:

> On 6/22/23 10:36, Bj=C3=B6rn T=C3=B6pel wrote:
>> From: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>
>>
>> The RISC-V vector specification states:
>>    Executing a system call causes all caller-saved vector registers
>>    (v0-v31, vl, vtype) and vstart to become unspecified.
>
> So the only use case of saving/restoring V regs in __switch_to is an=20
> interrupt induced task switch ?

Yes!