linux-kernel - Re: [PATCH v4 3/6] RISC-V: hwprobe: Add support for RISCV_HWPROBE_BASE_BEHAVIOR

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Date:   Tue, 21 Mar 2023 21:25:56 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     Palmer Dabbelt <palmer@...osinc.com>,
        Evan Green <evan@...osinc.com>
Cc:     slewis@...osinc.com, Conor Dooley <conor@...nel.org>,
        vineetg@...osinc.com, Evan Green <evan@...osinc.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrew Bresticker <abrestic@...osinc.com>,
        Celeste Liu <coelacanthus@...look.com>,
        Guo Ren <guoren@...nel.org>, Jonathan Corbet <corbet@....net>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v4 3/6] RISC-V: hwprobe: Add support for
 RISCV_HWPROBE_BASE_BEHAVIOR_IMA

Am Dienstag, 14. März 2023, 19:32:17 CET schrieb Evan Green:
> We have an implicit set of base behaviors that userspace depends on,
> which are mostly defined in various ISA specifications.
> 
> Co-developed-by: Palmer Dabbelt <palmer@...osinc.com>
> Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
> Signed-off-by: Evan Green <evan@...osinc.com>
> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>

This needs one fix, described blow, with that applied:
Reviewed-by: Heiko Stuebner <heiko.stuebner@...ll.eu>


> +	case RISCV_HWPROBE_KEY_IMA_EXT_0:
> +		pair->value = 0;
> +		if (has_fpu())
> +			pair->value |= RISCV_HWPROBE_IMA_FD;
> +
> +		if (elf_hwcap & RISCV_ISA_EXT_c)

This wants to be 
		if (elf_hwcap & riscv_isa_extension_mask(c))

i.e. elf_hwcap is a bitmap, RISCV_ISA_EXT_c is the number "2" and
riscv_isa_extension_mask() will get you the shifted bit.


> +			pair->value |= RISCV_HWPROBE_IMA_C;
> +
> +		break;
>  
>  	/*
>  	 * For forward compatibility, unknown keys don't fail the whole
> 

Heiko