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Message-ID: <1ddd4fb6-033e-5a94-876d-086af3eb1cf8@suse.com> Date: Wed, 22 Mar 2023 15:02:28 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v5 5/7] xen/riscv: introduce trap_init() Content-Language: en-US To: Julien Grall Cc: Andrew Cooper , Stefano Stabellini , Gianluca Guida , Bob Eshleman , Alistair Francis , Connor Davis , Oleksii , xen-devel@lists.xenproject.org References: <91b0284d20f530f2795a119ccb7436ee0b800256.1678976127.git.oleksii.kurochko@gmail.com> <5a2c6f35-373a-de3c-1db2-aeeb1b39635f@xen.org> <520d64f0b6cd283416aa4fb7b9baa5f83454c4a8.camel@gmail.com> <370a6e223d8db5f2d075ca8aba31db198a3aefce.camel@gmail.com> From: Jan Beulich In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: FR2P281CA0078.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:9a::20) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|DBBPR04MB7723:EE_ X-MS-Office365-Filtering-Correlation-Id: 3396b380-fd91-42cd-3dce-08db2ade134e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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From my understanding, with > -noPIE, the compiler would be free to use absolute address rather than > pc-relative one. Do you have any pointer to documentation that would > back your reasoning? It might for RV32 (using lui), but for 64-bit the ISA simply doesn't have any halfway efficient means to load addresses in other than a PC-relative manner [1]. -nopie really suppresses the compiler emitting code going through .got (which then indeed would mean using absolute addresses). I understand that at least for now RV32 isn't really of interest; if it were, I guess the concern would be more significant. Jan [1] There aren't even suitable relocations to express such in ELF, because you'd need to have a way to get at the top 32 bits of an address. The only alternative would be .got-like indirection without actually using .got.