[{"id":3683638,"web_url":"http://patchwork.ozlabs.org/comment/3683638/","msgid":"","list_archive_url":null,"date":"2026-04-28T18:20:40","subject":"Re: [PATCH v2 2/4] fastboot: Add GPT/MBR partition table flashing\n helper functions","submitter":{"id":6170,"url":"http://patchwork.ozlabs.org/api/people/6170/","name":"Simon Glass","email":"sjg@chromium.org"},"content":"Hi Balaji,\n\nOn 2026-04-27T12:06:41, Balaji Selvanathan\n wrote:\n> fastboot: Add GPT/MBR partition table flashing helper functions\n>\n> Add fastboot_flash_gpt_partition_table() and\n> fastboot_flash_mbr_partition_table() helper functions that handle\n> flashing of GPT and MBR partition tables to block devices.\n>\n> The MMC backend now uses these helper functions for GPT and MBR\n> operations, simplifying the code while maintaining the same\n> functionality.\n>\n> Signed-off-by: Balaji Selvanathan \n>\n> drivers/fastboot/fb_common.c | 94 ++++++++++++++++++++++++++++++++++++++++++++\n> drivers/fastboot/fb_mmc.c | 49 ++++-------------------\n> include/fastboot-internal.h | 30 ++++++++++++++\n> 3 files changed, 131 insertions(+), 42 deletions(-)\n\n> diff --git a/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c\n> @@ -245,3 +245,97 @@ void fastboot_init(void *buf_addr, u32 buf_size)\n> + dev_desc = blk_get_dev(interface, device);\n> + if (!dev_desc) {\n> + fastboot_fail(\"no such device\", response);\n> + return;\n> + }\n\nLooks like a regression for the MMC path: the current\nfastboot_mmc_get_dev() rejects dev_desc->type == DEV_TYPE_UNKNOWN (mmc\ndriver present but no card) and reports 'invalid mmc device'. That\ncheck is gone after this refactor, so an unprobed mmc falls through to\nis_valid_gpt_buf() / write_mbr_and_gpt_partitions() with an unusable\ndev_desc - please add the DEV_TYPE_UNKNOWN check in both helpers so\nthe common path is at least as strict as the code it replaces.\n\n> diff --git a/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c\n> @@ -245,3 +245,97 @@ void fastboot_init(void *buf_addr, u32 buf_size)\n> +#if CONFIG_IS_ENABLED(EFI_PARTITION)\n> +/**\n> + * fastboot_flash_gpt_partition_table() - Flash GPT partition table\n> + * @interface: Block interface name (e.g., 'mmc', 'scsi')\n> + * @device: Device number\n> + * @download_buffer: Buffer containing GPT data\n> + * @response: Fastboot response buffer\n> + */\n> +void fastboot_flash_gpt_partition_table(const char *interface,\n> + int device,\n> + void *download_buffer,\n> + char *response)\n\nThe two helpers are almost identical - only is_valid_*_buf(),\nwrite_mbr_*() and a couple of printed strings differ. Please factor\nthe common parts (interface check, blk_get_dev(), DEV_TYPE_UNKNOWN\ncheck, part_init() + okay) and have the GPT and MBR variants supply\njust the validate/write step. As written, the fail-paths are\nduplicated and will drift over time.\n\n> diff --git a/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c\n> @@ -245,3 +245,97 @@ void fastboot_init(void *buf_addr, u32 buf_size)\n> + if (is_valid_gpt_buf(dev_desc, download_buffer)) {\n> + printf(\"%s: invalid GPT - refusing to write to flash\\n\", __func__);\n\nfb_common.c does not include or even though it now\ncalls blk_get_dev(), is_valid_gpt_buf(),\nwrite_mbr_and_gpt_partitions(), is_valid_dos_buf(), write_mbr_sector()\nand part_init(). It builds today via a transitive include, but let's\nadd explicit includes.\n\n> diff --git a/drivers/fastboot/fb_mmc.c b/drivers/fastboot/fb_mmc.c\n> @@ -343,7 +343,7 @@ int fastboot_mmc_get_part_info(const char *part_name,\n> -static struct blk_desc *fastboot_mmc_get_dev(char *response)\n> +static struct blk_desc __maybe_unused *fastboot_mmc_get_dev(char *response)\n\nThe convention is 'static __maybe_unused struct blk_desc\n*fastboot_mmc_get_dev(...)'\n\n> diff --git a/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c\n> @@ -245,3 +245,97 @@ void fastboot_init(void *buf_addr, u32 buf_size)\n> + if (!interface || !strcmp(interface, \"\")) {\n> + fastboot_fail(\"block interface isn't provided\", response);\n> + return;\n> + }\n\nThe MMC caller passes the literal 'mmc', so this branch is dead on\nthat path. The check is really for the block backend in patch 3, where\nthe interface comes from CONFIG_FASTBOOT_FLASH_BLOCK_INTERFACE_NAME.\nThat validation belongs in the block caller (alongside the\nparse_device_partition() call), not duplicated in both common helpers\n- same reason fastboot_block_get_part_info() already does the check\nitself.\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=nh0yD/nA;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.denx.de\n (client-ip=85.214.62.61; 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=\"nh0yD/nA\";\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 [85.214.62.61])\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 4g4pf33Zzlz1xrS\n\tfor ; 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Tue, 28 Apr 2026\n 11:20:52 -0700 (PDT)","MIME-Version":"1.0","References":"<20260427-fb_gpt-v2-0-9e7fe3c1649a@oss.qualcomm.com>\n <20260427-fb_gpt-v2-2-9e7fe3c1649a@oss.qualcomm.com>","In-Reply-To":"<20260427-fb_gpt-v2-2-9e7fe3c1649a@oss.qualcomm.com>","From":"Simon Glass ","Date":"Tue, 28 Apr 2026 12:20:40 -0600","X-Gm-Features":"AVHnY4LzCiSBJPtnzOfQSQcawaZVtaiMDef1jEH-jL2IekXwcrs20RL3s6rAx-M","Message-ID":"\n ","Subject":"Re: [PATCH v2 2/4] fastboot: Add GPT/MBR partition table flashing\n helper functions","To":"balaji.selvanathan@oss.qualcomm.com","Cc":"u-boot@lists.denx.de, Mattijs Korpershoek ,\n Tom Rini , Heiko Schocher ,\n Neil Armstrong ,\n Dmitrii Merkurev ,\n Adrian Freihofer , Peng Fan ,\n Jaehoon Chung ,\n \"Ariel D'Alessandro\" ","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"}}]