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Thu, 26 Mar 2026 17:33:51 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AUJnWW6OA6Vc Date: Thu, 26 Mar 2026 22:33:14 +0100 From: "Arnd Bergmann" To: "Russell King" , "Christian Schrefl" Cc: "Miguel Ojeda" , "Alice Ryhl" , "Ard Biesheuvel" , "Jamie Cunliffe" , "Will Deacon" , "Catalin Marinas" , "Miguel Ojeda" , "Andreas Hindborg" , acourbot@nvidia.com, "Andrew Morton" , "Anton Ivanov" , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , "Boqun Feng" , "Danilo Krummrich" , "David Gow" , "Gary Guo" , "Johannes Berg" , "Justin Stitt" , linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-um@lists.infradead.org, llvm@lists.linux.dev, "Benno Lossin" , "Mark Rutland" , mmaurer@google.com, "Bill Wendling" , "Nathan Chancellor" , "Nick Desaulniers" , "Nicolas Schier" , "Nicolas Schier" , "Peter Zijlstra" , "Richard Weinberger" , rust-for-linux@vger.kernel.org, "Trevor Gross" , "Uladzislau Rezki (Sony)" Message-Id: <641592e3-2354-4238-9eb8-a1f5c2a13126@app.fastmail.com> In-Reply-To: References: <20260322192159.88138-1-ojeda@kernel.org> <20260323000327.111235-1-ojeda@kernel.org> <9cf5a94c-0f37-446c-b63d-ddac5674d220@gmail.com> Subject: Re: [PATCH v2 0/3] Inline helpers into Rust without full LTO Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Thu, Mar 26, 2026, at 16:18, Russell King (Oracle) wrote: > On Thu, Mar 26, 2026 at 03:31:26PM +0100, Christian Schrefl wrote: >> On 3/26/26 2:47 PM, Miguel Ojeda wrote: >> > On Thu, Mar 26, 2026 at 11:10=E2=80=AFAM Alice Ryhl wrote: > > I'm not sure if this is still true, but I believe it used to be the ca= se > that the -linux-gnueabi target has one behaviour for enums (fixed size) > whereas -none-eabi, the size of the type depends on the range of values > included in the enum. I checked Debian's arm-none-eabi-gcc, which indeed still has this behavi= or: $ echo 'enum { A, B } x =3D sizeof(x);' | arm-none-eabi-gcc -xc - -O2 -o= - -S | grep -A1 x: x: .byte 1 and I see the same thing for the hexagon target in clang, but none of the other targets that Linux runs on. In particular, clang always behaves like linux-gnueabi even when targeting plain eabi. $ echo 'enum { A, B } x =3D sizeof(x);' | clang --target=3Darm-none-eabi= -xc - -O2 -o- -S | grep -A1 x: x: .long 4 I noticed a similar issue with m68k-linux, which has a bitfield alignment different from anything else on gcc, but uses the normal behavior on clang. Arnd