linux-kernel - Re: [PATCH v4 3/5] partitions/efi: add support for uImage.FIT sub-partitions

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Date:   Wed, 9 Nov 2022 10:13:48 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Daniel Golle <daniel@...rotopia.org>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Matthew Wilcox <willy@...radead.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Ming Lei <ming.lei@...hat.com>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-efi@...r.kernel.org
Subject: Re: [PATCH v4 3/5] partitions/efi: add support for uImage.FIT sub-partitions

On Wed, 9 Nov 2022 at 00:05, Daniel Golle <daniel@...rotopia.org> wrote:
>
> Add new GUID allowing to parse uImage.FIT stored in a GPT partition
> and map filesystem sub-image as sub-partitions.
>
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>

I'm not sure I follow the logic here.

You are adding uImage.FIT support as a pseudo-partition type right?
And the only partition driver that supports it is GPT?

Does that mean that all the other types would need a similar change to
be able to detect these subvolumes?

> ---
>  block/partitions/efi.c | 9 +++++++++
>  block/partitions/efi.h | 3 +++
>  2 files changed, 12 insertions(+)
>
> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index 5e9be13a56a8..bf87893eabe4 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -716,6 +716,9 @@ int efi_partition(struct parsed_partitions *state)
>         gpt_entry *ptes = NULL;
>         u32 i;
>         unsigned ssz = queue_logical_block_size(state->disk->queue) / 512;
> +#ifdef CONFIG_FIT_PARTITION
> +       u32 extra_slot = 65;
> +#endif
>
>         if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
>                 kfree(gpt);
> @@ -749,6 +752,12 @@ int efi_partition(struct parsed_partitions *state)
>                                 ARRAY_SIZE(ptes[i].partition_name));
>                 utf16_le_to_7bit(ptes[i].partition_name, label_max, info->volname);
>                 state->parts[i + 1].has_info = true;
> +               /* If this is a U-Boot FIT volume it may have subpartitions */
> +#ifdef CONFIG_FIT_PARTITION
> +               if (!efi_guidcmp(ptes[i].partition_type_guid, PARTITION_LINUX_FIT_GUID))
> +                       (void) parse_fit_partitions(state, start * ssz, size * ssz,
> +                                                   &extra_slot, 127, 1);
> +#endif
>         }
>         kfree(ptes);
>         kfree(gpt);
> diff --git a/block/partitions/efi.h b/block/partitions/efi.h
> index 84b9f36b9e47..06c11f6ae398 100644
> --- a/block/partitions/efi.h
> +++ b/block/partitions/efi.h
> @@ -51,6 +51,9 @@
>  #define PARTITION_LINUX_LVM_GUID \
>      EFI_GUID( 0xe6d6d379, 0xf507, 0x44c2, \
>                0xa2, 0x3c, 0x23, 0x8f, 0x2a, 0x3d, 0xf9, 0x28)
> +#define PARTITION_LINUX_FIT_GUID \
> +    EFI_GUID( 0xcae9be83, 0xb15f, 0x49cc, \
> +              0x86, 0x3f, 0x08, 0x1b, 0x74, 0x4a, 0x2d, 0x93)
>
>  typedef struct _gpt_header {
>         __le64 signature;
> --
> 2.38.1
>