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Mon, 27 Jan 2025 14:34:20 +0000 Date: Mon, 27 Jan 2025 14:34:15 +0000 From: Bruce Richardson To: Stephen Hemminger CC: Morten =?iso-8859-1?Q?Br=F8rup?= , Subject: Re: [PATCH] build: force gcc to initialize padding bits Message-ID: References: <20250123172048.134417-1-stephen@networkplumber.org> <98CBD80474FA8B44BF855DF32C47DC35E9F9E6@smartserver.smartshare.dk> <20250124103748.6b9b85fa@hermes.local> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250124103748.6b9b85fa@hermes.local> X-ClientProxiedBy: DU6P191CA0015.EURP191.PROD.OUTLOOK.COM (2603:10a6:10:540::16) To CY8PR11MB7290.namprd11.prod.outlook.com (2603:10b6:930:9a::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY8PR11MB7290:EE_|IA0PR11MB7306:EE_ X-MS-Office365-Filtering-Correlation-Id: 2a281e4f-091c-48b8-b065-08dd3edfafeb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?TBDPDVn7tMij5/fN4g70aLtBRc6vH/gp1e/tB1TdgbRzuVT60Sgfx3J++QLy?= =?us-ascii?Q?57WQ/Mbz8WR9NqmuzQ3vAEs02Ft3Wu3PZuLa4guLp6d+ZSP1dtyYj8LVToIm?= =?us-ascii?Q?7wsxSu/IFmI7EISt7DH5av7tVRQXU72BK3HIFjpbL1UWZH54QNBIw9mxNWth?= =?us-ascii?Q?sK5aHMPs0xvBdMTW843Xt+6OiEH5nAGj2MnUFx01/9e/rHeinOv+0FN7vfS4?= =?us-ascii?Q?Mi1Zg5Tcb0Du9yof1we7AxDw2LZTmSjaeHej/1TMw/abwsKRB9bPomdudVR+?= =?us-ascii?Q?EUBroBv5i+u1RKOhyvgcb/PqEaVEpGu2nblo6y1bIrUd0tWTDZ1piz2trctr?= =?us-ascii?Q?GzlgqxL0dliDtOJFNpKT6FvfTLDpBV+IESs7FnHvttwAiKeKEf/Crwx8pnk7?= =?us-ascii?Q?SJF0g5LctbtsCGEz8uE5PuCHXUFkPOPxS+RWiWUnwq5dhXxf8Myqkvl1V0b4?= =?us-ascii?Q?X3hTUZkHrSRJMEEpTQNsyAF0CisEL/RoB2yToQIBY+m6f/k95mH5cKK9V3wV?= =?us-ascii?Q?5/koJ3vr4QyXhfZ2y8x8/eEtLssMkyPlNdml7txzqPuin7Lbn8scRyu8g4TO?= =?us-ascii?Q?zeB6mzHd71o/ghpqRBmBkUdbyGR8ldKnXXGbAjIb4VILpidY+ExUzdLH/ZyR?= =?us-ascii?Q?G8bVbSl03FekvMHGKkSSwgi4f4UqnoVdGdr++lNTtJN3gS9fGuZBFEIfHBlG?= =?us-ascii?Q?afzdNxxg45OosclyXlhzVgCJiWW9x46xsQVbpcboqvUlggDymn8Zu9NRv3kY?= =?us-ascii?Q?rnnQR0SUpjbKUNchHrfYe1gYrdmqpZCg9Fn7vcw8QkoMfNGHrDwHnPTvEoJN?= =?us-ascii?Q?waM/PxY6mWdLc+1BOI83hhXDFZH1J3bBvpYT0Zz1LO9wcSG6+mA/qvsBwP87?= =?us-ascii?Q?PUslNDgg3vJAUWnME0W58eglXZFHdxNpbCGkfvsjAJSkvJbKG92S4ykFtxAb?= =?us-ascii?Q?LjVXS2pZ6nCQbYltanjzZjrB8JMMxl8fsb68l5v3qLA4PNC6GdkwOGkPvafz?= =?us-ascii?Q?/baijWpl0ET+w8S/0GEJrI96rZfOh36LR3AEfhZN2lTB92Hg8kRBRw32pH5a?= =?us-ascii?Q?UK9K63bRuRt6pZE/jr6pJJk37nHfjQmR6CLmKJRf1ayT1ED9ys3SdMxZ7ro/?= =?us-ascii?Q?E4ZzAnTdalH/tdRACzBCUB0ZG2fYa8TP2yOhTO1XCFSfF2V1yiE23mH++xaO?= =?us-ascii?Q?YOx5zgrJnmeGAEbTWl8A9jkYkUVTfBz+93NUorQlbKLq3p9lrH8qWGFYPCA6?= =?us-ascii?Q?pisY+rNwM8W0OSbuuczQ13AXGR3BBRtgEQOxSKy60Gy6YTIq0xrlsopq9bH2?= =?us-ascii?Q?PKC98YR21Af8bc8pT/sA5n9MoElPwY05GWi91F44F+sL7yUhttawJrvgYUwt?= =?us-ascii?Q?4HW+kjkZ4F5IglHygBLywKhxXVNI?= X-Forefront-Antispam-Report: CIP:255.255.255.255; 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From my reading of the gcc doc[1], > > "..padding-bits=union" corresponds to the old behaviour, right? > > > > This also means we will have different padding behaviour on clang and gcc, > > since clang (at least v18 on my board) doesn't support this flag. Do we see > > any issues with that? > > > > /Bruce > > I chose the setting based on some email with the Linux kernel hardening > project and their choice. > > Clang decided to fix and just do the right thing. > > > https://github.com/llvm/llvm-project/commit/7a086e1b2dc05f54afae3591614feede727601fa Excellent. Agree on initializing everything being "the right thing".