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X-CSE-ConnectionGUID: Q4IWf3tbQbSR5vCnCj+0JQ== X-CSE-MsgGUID: 2mHqQ/UqRtqMoYclSMeeXQ== X-IronPort-AV: E=McAfee;i="6800,10657,11818"; a="81303518" X-IronPort-AV: E=Sophos;i="6.24,206,1774335600"; d="scan'208";a="81303518" Received: from fmviesa010.fm.intel.com ([10.60.135.150]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2026 09:46:40 -0700 X-CSE-ConnectionGUID: KrhAIdYYSd29psL411RRxg== X-CSE-MsgGUID: 5tK2djymRoyAPEr8zqR6PQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,206,1774335600"; d="scan'208";a="243354445" Received: from bradocaj-mobl.ger.corp.intel.com (HELO [10.125.111.24]) ([10.125.111.24]) by fmviesa010-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2026 09:46:39 -0700 Message-ID: <03be57ae-0e41-4b8a-adc5-bdd85ccce951@intel.com> Date: Mon, 15 Jun 2026 09:46:41 -0700 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 12/19] x86: define DPS root partition type UUIDs To: Vincent Mailhol , Jens Axboe , Davidlohr Bueso , Alexander Viro , Christian Brauner , Jan Kara Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-efi@vger.kernel.org, linux-fsdevel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org References: <20260615-discoverable-root_partitions-v1-0-39c78fac42e2@kernel.org> <20260615-discoverable-root_partitions-v1-12-39c78fac42e2@kernel.org> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/15/26 09:09, Vincent Mailhol wrote: > +#ifdef CONFIG_X86_64 > +#define DPS_ROOT_PARTITION_TYPE_UUID "4f68bce3-e8cd-4db1-96e7-fbcaf984b709" > +#else > +#define DPS_ROOT_PARTITION_TYPE_UUID "44479540-f297-41b2-9af7-d131d5f0458a" > +#endif This doesn't make a whole lot of sense to me. 64-bit kernels can run 32-bit userspace just fine. But this #ifdef as proposed means that only a 32-bit *OR* 64-bit kernel can auto-discover a given partition. I kinda think you should just have an array of strings for these things, maybe glued together with some preprocessor magic. Logically something like this: const char* const uuids[] = { #ifdef CONFIG_ARM64 "b921b045-1df0-41c3-af44-4c6f280d3fae" #endif #ifdef CONFIG_X86_64 "4f68bce3-e8cd-4db1-96e7-fbcaf984b709", #endif #if defined(CONFIG_X86) && defined(CONFIG_COMPAT32) "44479540-f297-41b2-9af7-d131d5f0458a", #endif ... }; ... and then search the array. I honestly don't think you need to sprinkle UUIDs all over the architectures. It could probably also be done almost entirely in Kconfig. This could be in, say block/partitions/Kconfig, or arch/*/Kconfig: config DPS_ROOT_PARTITION_TYPE_UUID_1 string default "4f68bce3-e8cd-4db1-96e7-fbcaf984b709" if X86_64 default "b921b045-1df0-41c3-af44-4c6f280d3fae" if ARM64 ... config DPS_ROOT_PARTITION_TYPE_UUID_2 string default "44479540-f297-41b2-9af7-..." if X86 && COMPAT_32 const char* const uuids[] = { #ifdef CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_1 CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_1 #endif #ifdef CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_2 CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_2 #endif ... }; There are a lot of ways to do this. I'm just not a super big fan of the current proposal. So, boiling it down: 1. Should more than one UUID be supported per kernel build? 2. Should the UUIDs be defined in arch code or generic code? 3. Kconfig or #ifdefs?