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Mon, 6 Apr 2026 16:30:53 +0000 Received: from DS0PR12MB6486.namprd12.prod.outlook.com ([fe80::88a9:f314:c95f:8b33]) by DS0PR12MB6486.namprd12.prod.outlook.com ([fe80::88a9:f314:c95f:8b33%4]) with mapi id 15.20.9769.014; Mon, 6 Apr 2026 16:30:53 +0000 Message-ID: Date: Mon, 6 Apr 2026 12:30:51 -0400 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] gpu: nova-core: require little endian To: Eliot Courtney , Danilo Krummrich , Alexandre Courbot , Alice Ryhl , David Airlie , Simona Vetter Cc: John Hubbard , Alistair Popple , Timur Tabi , rust-for-linux@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20260406-fix-kconfig-v1-1-8f634499f7f0@nvidia.com> Content-Language: en-US From: Joel Fernandes In-Reply-To: <20260406-fix-kconfig-v1-1-8f634499f7f0@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BN9PR03CA0984.namprd03.prod.outlook.com (2603:10b6:408:109::29) To DS0PR12MB6486.namprd12.prod.outlook.com (2603:10b6:8:c5::21) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB6486:EE_|IA1PR12MB8079:EE_ X-MS-Office365-Filtering-Correlation-Id: 586dc9d0-470d-4ea4-747a-08de93f9df4c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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For > example, all the code that reads RPCs out of the command queue just > directly interprets the bytes. Oh yeah, its not just the driver making assumptions, it is the hardware itself. The Nvidia GPU architecture is little-endian (including MMU structures in VRAM). > > Make this explicit in Kconfig. > > Signed-off-by: Eliot Courtney > --- > The current code assumes little endian in a bunch of places. I think we > should either explicitly decide to be generic on endianness or explicitly > decide not to - having some handling sprinkled around in various > locations seems confusing to me. > > I believe that currently e.g. `RUST` transitively depends on > !CPU_BIG_ENDIAN, so this is more about making the decision explicit for > nova-core rather than fixing any kind of hole. > --- > drivers/gpu/nova-core/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/nova-core/Kconfig b/drivers/gpu/nova-core/Kconfig > index a4f2380654e2..d8456f8eaa05 100644 > --- a/drivers/gpu/nova-core/Kconfig > +++ b/drivers/gpu/nova-core/Kconfig > @@ -3,6 +3,7 @@ config NOVA_CORE > depends on 64BIT > depends on PCI > depends on RUST > + depends on !CPU_BIG_ENDIAN If we want to do this, I am Ok. Although I am also Ok with the potential transitive Rust dependency in which case the only value of adding it in Kconfig is documentation. But just a side note (not a rejection comment), Nouveau does not do this, and no other GPU driver afaics either. thanks, -- Joel Fernandes