[{"id":3672807,"web_url":"http://patchwork.ozlabs.org/comment/3672807/","msgid":"","list_archive_url":null,"date":"2026-04-02T16:37:27","subject":"Re: [2/4] boot: fit: support generating DM verity cmdline parameters","submitter":{"id":6170,"url":"http://patchwork.ozlabs.org/api/people/6170/","name":"Simon Glass","email":"sjg@chromium.org"},"content":"Hi Daniel,\n\nOn 2026-04-02T03:08:27, Daniel Golle wrote:\n> boot: fit: support generating DM verity cmdline parameters\n> boot: fit: support generating DM verity cmdline parameters\n>\n> Add fit_verity_build_cmdline(): when a FILESYSTEM loadable carries a\n> dm-verity subnode, construct the dm-mod.create= kernel cmdline parameter\n> from the verity metadata (block-size, data-blocks, algo, root-hash,\n> salt) and append it to bootargs.\n>\n> Also add dm-mod.waitfor=/dev/fit0[,/dev/fitN] for each dm-verity device\n> so the kernel waits for the underlying FIT block device to appear before\n> setting up device-mapper targets. This is needed when the block driver\n> probes late, e.g. because it depends on NVMEM calibration data.\n>\n> The dm-verity target references /dev/fitN where N is the loadable's\n> index in the configuration -- matching the order Linux's FIT block\n> driver assigns block devices. hash-start-block is read directly from\n> the FIT dm-verity node; mkimage ensures its value equals num-data-blocks\n> by invoking veritysetup with --no-superblock.\n>\n> Signed-off-by: Daniel Golle \n\n> diff --git a/boot/Kconfig b/boot/Kconfig\n> @@ -142,6 +142,27 @@ config FIT_CIPHER\n> +config FIT_VERITY\n> + ...\n> + and BOOTSTD bootmeths.\n> +\n> +\n\nDrop extra blank line.\n\n> diff --git a/boot/image-fit.c b/boot/image-fit.c\n> @@ -2642,3 +2682,299 @@ out:\n> + if (!data_block_size || data_block_size < 512 ||\n> + !hash_block_size || hash_block_size < 512 ||\n> + !num_data_blocks)\n> + return -EINVAL;\n\ndm-verity requires block sizes to be a power of two (and divisible by\n512). The first check `!data_block_size` is redundant given the `<\n512` check that follows. Please can you add a power-of-two validation\nusing is_power_of_2() from ? Otherwise the kernel will\nlikely reject the table at boot time with a confusing error.\n\n> diff --git a/boot/image-fit.c b/boot/image-fit.c\n> @@ -2642,3 +2682,299 @@ out:\n> +int fit_verity_build_cmdline(const void *fit, int conf_noffset,\n> + struct bootm_headers *images)\n> +{\n> + ...\n> + if (found) {\n> + /* Transfer ownership to the bootm_headers */\n> + images->dm_mod_create = dm_create;\n> + images->dm_mod_waitfor = dm_waitfor;\n> + } else {\n> + free(dm_create);\n> + free(dm_waitfor);\n> + }\n> +\n> + return found;\n\nWhen found > 0, this returns a positive value which could be confused\nwith an error by callers that only check `< 0`. The call site in\nboot_get_loadable() does `if (fit_img_result < 0) return\nfit_img_result;` so it works, but I suspect returning 0 for success\nand keeping the count internal would be cleaner. What do you think?\n\n> diff --git a/boot/bootm.c b/boot/bootm.c\n> @@ -242,6 +242,7 @@ static int boot_get_kernel(...)\n> static int bootm_start(void)\n> {\n> + fit_verity_free(&images);\n> memset((void *)&images, 0, sizeof(images));\n\nJust to check: fit_verity_free() is called here before memset(), which\nmeans the pointers must already be valid (or NULL) from a prior boot\nattempt. This works because fit_verity_free() checks for NULL\ninternally, and .bss is zeroed. How about a comment explaining the\nordering?\n\nRegards,\nSimon","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=chromium.org header.i=@chromium.org header.a=rsa-sha256\n header.s=google header.b=QpZgiL6S;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.denx.de\n (client-ip=2a01:238:438b:c500:173d:9f52:ddab:ee01; helo=phobos.denx.de;\n envelope-from=u-boot-bounces@lists.denx.de; receiver=patchwork.ozlabs.org)","phobos.denx.de;\n dmarc=pass (p=none dis=none) header.from=chromium.org","phobos.denx.de;\n spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de","phobos.denx.de;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=chromium.org header.i=@chromium.org\n header.b=\"QpZgiL6S\";\n\tdkim-atps=neutral","phobos.denx.de;\n dmarc=pass (p=none dis=none) header.from=chromium.org","phobos.denx.de;\n spf=pass smtp.mailfrom=sjg@chromium.org"],"Received":["from phobos.denx.de (phobos.denx.de\n [IPv6:2a01:238:438b:c500:173d:9f52:ddab:ee01])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fmnZx1mvJz1xtJ\n\tfor ; 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Thu, 02 Apr 2026\n 09:37:39 -0700 (PDT)","MIME-Version":"1.0","References":"\n <6cc0f6ccf692d97dafc073e08195e54b712882b4.1775099118.git.daniel@makrotopia.org>","In-Reply-To":"\n <6cc0f6ccf692d97dafc073e08195e54b712882b4.1775099118.git.daniel@makrotopia.org>","From":"Simon Glass ","Date":"Thu, 2 Apr 2026 10:37:27 -0600","X-Gm-Features":"AQROBzDG6uR86I9CNH7fALfAmXOE-k-XMPjxAQkPyTsr6jPaFsIzY9daRnmpTrM","Message-ID":"\n ","Subject":"Re: [2/4] boot: fit: support generating DM verity cmdline parameters","To":"daniel@makrotopia.org","Cc":"Tom Rini , Quentin Schulz ,\n Kory Maincent , Simon Glass ,\n Mattijs Korpershoek , Peng Fan ,\n Marek Vasut ,\n Martin Schwan , Anshul Dalal ,\n Ilias Apalodimas ,\n Sughosh Ganu ,\n =?utf-8?b?54mbIOW/l+Wujw==?= ,\n Benjamin ROBIN , Aristo Chen ,\n James Hilliard ,\n Frank Wunderlich ,\n Mayuresh Chitale ,\n Neil Armstrong ,\n Wolfgang Wallner ,\n Rasmus Villemoes , Francois Berder ,\n Shiji Yang , u-boot@lists.denx.de","Content-Type":"text/plain; charset=\"UTF-8\"","X-BeenThere":"u-boot@lists.denx.de","X-Mailman-Version":"2.1.39","Precedence":"list","List-Id":"U-Boot discussion ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"u-boot-bounces@lists.denx.de","Sender":"\"U-Boot\" ","X-Virus-Scanned":"clamav-milter 0.103.8 at phobos.denx.de","X-Virus-Status":"Clean"}}]