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Mon, 19 Oct 2026 18:13:38 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-ThreadId: ATLhSvAouVZo Date: Tue, 20 Oct 2026 00:12:57 +0200 From: "Arnd Bergmann" To: "Ian Rogers" , "Thomas Gleixner" , "Andy Lutomirski" , "Vincenzo Frascino" , "Stefan Kerkmann" , "Marc Kleine-Budde" , "Christophe Leroy" Cc: "David Laight" , "Arnaldo Carvalho de Melo" , "Namhyung Kim" , "Eric Biggers" , "Alexander Viro" , "Jason A . Donenfeld" , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: <31fe09f6-0a14-40fc-8ad8-c03998fb1f5c@app.fastmail.com> In-Reply-To: <20261019201257.3805356-1-irogers@google.com> References: <20261019201257.3805356-1-irogers@google.com> Subject: Re: [PATCH v1 1/2] vdso: Add VDSO_UNALIGNED_PACKED config option for ARMv5 Content-Type: text/plain Content-Transfer-Encoding: 7bit On Mon, Oct 19, 2026, at 22:12, Ian Rogers wrote: > + > +config VDSO_UNALIGNED_PACKED > + bool > + default CPU_32v5 > + help > + Use packed structs rather than memcpy() in include/vdso/unaligned.h > + for unaligned memory accesses. Enabled on ARMv5 where GCC may emit > + out-of-line memcpy() calls instead of inlining byte accesses. As explained, I think this misrepresents the problem as Arm specific and isn't the correct method for -munaligned-access targets on Arm, which include CPU_32v3, CPU_32v4 and CPU_32v4T along with CPU_32v5. I still hope we can use a version that just produces the intended code on both -munaligned-access and -mno-unaligned-access targets like the old version did. Arnd