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Fri, 07 Feb 2025 17:22:55 -0800 (PST) Received: from ghost ([50.145.13.30]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-ad51af7a221sm3736753a12.75.2025.02.07.17.22.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Feb 2025 17:22:54 -0800 (PST) Date: Fri, 7 Feb 2025 17:22:52 -0800 From: Charlie Jenkins To: Andrew Jones Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com, jesse@rivosinc.com, Anup Patel Subject: Re: [PATCH 7/9] riscv: Prepare for unaligned access type table lookups Message-ID: References: <20250207161939.46139-11-ajones@ventanamicro.com> <20250207161939.46139-18-ajones@ventanamicro.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20250207161939.46139-18-ajones@ventanamicro.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250207_172257_206787_34118D0A X-CRM114-Status: GOOD ( 10.45 ) 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 Fri, Feb 07, 2025 at 05:19:47PM +0100, Andrew Jones wrote: > Probing unaligned accesses on boot is time consuming. Provide a > function which will be used to look up the access type in a table > by id registers. Vendors which provide table entries can then skip > the probing. The access checker in my experience is only time consuming on slow hardware. Hardware that supports fast unaligned accesses isn't really impacted by this? Avoiding a list of hardware that has slow/fast unaligned accesses in the kernel was the main reason for dynamically checking. We did introduce the config option to compile the kernel with assumed slow/fast accesses, which of course has the downside of recompiling the kernel and I assume that you already considered that. Instead of having a table in the kernel, something that would be more platform agnostic would be to have an extension that signals this information. That seems like it would accomplish the same goal and leverage the existing infrastructure in the kernel, albeit with the need to make a new extension. - Charlie _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv