[PATCH v2 1/1] spl: allow loading via partition type GUID

[Simon Glass]

" properHi Heinrich,

On Thu, 16 Feb 2023 at 14:31, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
>
>
> On 2/16/23 21:17, Simon Glass wrote:
> > Hi Heinrich,
> >
> > On Thu, 16 Feb 2023 at 08:30, Heinrich Schuchardt
> > <heinrich.schuchardt at canonical.com> wrote:
> >>
> >> Some boards provide main U-Boot as a dedicated partition to SPL.
> >> Currently we can define either a fixed partition number or an MBR
> >> partition type to define which partition is to be used.
> >>
> >> Partition numbers tend to conflict with established partitioning schemes
> >> of Linux distros. MBR partitioning is more and more replaced by GPT
> >> partitioning.
> >>
> >> Allow defining a partition type GUID identifying the partition to load
> >> main U-Boot from.
> >>
> >> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> >> ---
> >> v2:
> >>          avoid if/endif in Kconfig
> >> ---
> >>   common/spl/Kconfig   | 27 ++++++++++++++++++++++-----
> >>   common/spl/spl_mmc.c | 13 +++++++++++++
> >>   2 files changed, 35 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/common/spl/Kconfig b/common/spl/Kconfig
> >> index 3c2af453ab..9d12b48297 100644
> >> --- a/common/spl/Kconfig
> >> +++ b/common/spl/Kconfig
> >> @@ -514,19 +514,36 @@ config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
> >>            used in raw mode
> >>
> >>   config SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
> >> -       bool "MMC raw mode: by partition type"
> >> +       bool "MMC raw mode: by MBR partition type"
> >>          depends on DOS_PARTITION && SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
> >>          help
> >> -         Use partition type for specifying U-Boot partition on MMC/SD in
> >> +         Use MBR partition type for specifying U-Boot partition on MMC/SD in
> >>            raw mode. U-Boot will be loaded from the first partition of this
> >>            type to be found.
> >>
> >>   config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION_TYPE
> >> -       hex "Partition Type on the MMC to load U-Boot from"
> >> +       hex "MBR Partition Type on the MMC to load U-Boot from"
> >>          depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
> >>          help
> >> -         Partition Type on the MMC to load U-Boot from, when the MMC is being
> >> -         used in raw mode.
> >> +         MBR Partition Type on the MMC to load U-Boot from, when the MMC is
> >> +         being used in raw mode.
> >> +
> >> +config SYS_MMCSD_RAW_MODE_U_BOOT_USE_GPT_PARTITION_TYPE
> >> +       bool "MMC raw mode: GPT by partition type"
> >> +       depends on PARTITION_TYPE_GUID && SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
> >> +       help
> >> +         Use GPT partition type for specifying U-Boot partition on MMC/SD in
> >> +         raw mode. U-Boot will be loaded from the first partition of this
> >> +         type to be found.
> >> +
> >> +config SYS_MMCSD_RAW_MODE_U_BOOT_GPT_PARTITION_TYPE
> >> +       string "GPT Partition Type on the MMC to load U-Boot from"
> >> +       depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_GPT_PARTITION_TYPE
> >> +       default d2f002f8-e4e7-4269-b8ac-3bb6fabeaff6
> >
> > What is this? Can we have a register of these hideous things and call
> > them by name?

Further, I don't see any documentation on this in U-Boot. Could you at
least add a list of these things?

> >
> >> +       help
> >> +         GPT Partition Type on the MMC to load U-Boot from, when the MMC is
> >> +         being used in raw mode. The GUID must be lower case, low endian,
> >> +         and formatted like d2f002f8-e4e7-4269-b8ac-3bb6fabeaff6.
> >>
> >>   config SUPPORT_EMMC_BOOT_OVERRIDE_PART_CONFIG
> >>          bool "Override eMMC EXT_CSC_PART_CONFIG by user defined partition"
> >> diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
> >> index e4135b2048..69bf1d6e98 100644
> >> --- a/common/spl/spl_mmc.c
> >> +++ b/common/spl/spl_mmc.c
> >> @@ -191,6 +191,19 @@ static int mmc_load_image_raw_partition(struct spl_image_info *spl_image,
> >>          struct disk_partition info;
> >>          int err;
> >>
> >> +#ifdef CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_GPT_PARTITION_TYPE
> >> +       for (int i = 1; i <= MAX_SEARCH_PARTITIONS; ++i) {
> >> +               err = part_get_info(mmc_get_blk_desc(mmc), i, &info);
> >> +               if (err)
> >> +                       continue;
> >> +               if (!strncmp(info.type_guid,
> >> +                            CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_GPT_PARTITION_TYPE,
> >> +                            UUID_STR_LEN)) {
> >> +                       partition = i;
> >> +                       break;
> >> +               }
> >> +       }
> >> +#endif
> >>   #ifdef CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
> >>          int type_part;
> >>          /* Only support MBR so DOS_ENTRY_NUMBERS */
> >> --
> >> 2.38.1
> >>
> >
> > Is it possible to avoid using #ifdef here?
>
> Unfortunately not. Field 'type_guid' is restricted by an #ifdef. So
> unconditional compilation would fail.

Do you think it is worth adding an accessor as we have done with some
global_data things?

>
> >
> > Longer term, I wonder if we can add a DT schema for all of
> > this...these CONFIG options for boot selection seem to be getting out
> > of hand!
>
> Tom just moved a lot of constants hard coded in C code to Kconfig with a
> big effort. Now you want to move Kconfig values to hard coded constants
> in device-tree.
>
> Running in circles does not sound like a winning strategy.

The values seem to be common across certain boards of the same type, SoC, etc.

I'm not sure, but at some point this is all going to get out of hand.
Already we have these options:

common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_DATA_PART_OFFSET
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION_TYPE
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_EMMC_BOOT_PARTITION
common/spl/Kconfig:config SYS_MMCSD_FS_BOOT_PARTITION
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_ARGS_SECTOR
common/spl/Kconfig:config SYS_MMCSD_RAW_MODE_ARGS_SECTORS

That is just for MMC raw mode.

For environment we have SYS_MMC_ENV_DEV and _PART. If you look around
you'll see loads of these options.

I see that rockchip uses u-boot,spl-boot-order as a way to determine
the boot order. This makes it configurable without rebuilding
U-Boot...although I don't think we need to make the MMC stuff
configurable, since I am assuming that the boot ROM determines at
least some of it...?

It seems that the whole thing is crying out for a bit of organisation
and a proper schema.

Regards,
Simon