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Thu, 24 Nov 2022 01:30:25 -0800 (PST) Date: Thu, 24 Nov 2022 10:30:21 +0100 From: Samuel Ortiz To: "Hongren (Zenithal) Zheng" Cc: Palmer Dabbelt , Paul Walmsley , Albert Ou , Atish Patra , Anup Patel , Eric Biederman , Kees Cook , linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Michael Kerrisk , linux-man@vger.kernel.org, Jiatai He , Heiko Stuebner , Conor.Dooley@microchip.com Subject: Re: [PATCH v3 2/3] RISC-V: uapi: add HWCAP for Bitmanip/Scalar Crypto Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221124_013029_389367_A832C858 X-CRM114-Status: GOOD ( 13.56 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Jun 13, 2022 at 02:46:35AM +0800, Hongren (Zenithal) Zheng wrote: > diff --git a/arch/riscv/include/uapi/asm/hwcap.h b/arch/riscv/include/uapi/asm/hwcap.h > index 46dc3f5ee99f..bfed3e5c338c 100644 > --- a/arch/riscv/include/uapi/asm/hwcap.h > +++ b/arch/riscv/include/uapi/asm/hwcap.h > @@ -22,4 +22,26 @@ > #define COMPAT_HWCAP_ISA_D (1 << ('D' - 'A')) > #define COMPAT_HWCAP_ISA_C (1 << ('C' - 'A')) > > +/* > + * HWCAP2 flags - for elf_hwcap2 (in kernel) and AT_HWCAP2 > + * > + * As only 32 bits of elf_hwcap (in kernel) could be used > + * and RISC-V has reserved 26 bits of it, other caps like > + * bitmanip and crypto can not be placed in AT_HWCAP > + */ Have we agreed that multi-letter ISA extensions would use hwcap to be exposed to userspace? With so many potential extensions, we could quickly run out of space on AT_HWCAP2 as well. Cheers, Samuel. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv