[U-Boot] [PATCH 1/1]: environment in eMMC boot partition

[Tom Rini <trini@konsulko.com>]

On Sat, Oct 08, 2016 at 03:41:50PM -0700, Sergey Kubushyn wrote:
> On Sat, 8 Oct 2016, Tom Rini wrote:
> 
> >On Wed, Oct 05, 2016 at 01:28:07PM -0700, Sergey Kubushyn wrote:
> >
> >>This allows to place U-Boot environment into eMMC boot partition thus
> >>saving space on user partition for the OS (or whatever.) When booting
> >>off of eMMC many (all?) MCUs can use dedicated boot0/boot1 partitions
> >>to boot so U-Boot (or SPL) is written to one (or both) such partitions.
> >>When such boot configuration is used it makes sense to place environment
> >>in the same partition where the U-Boot itself is so the entire user
> >>partition is available for the OS.
> >>
> >>It might be not well polished yet but it is a simple patch that can be
> >>reworked later.
> >>
> >>It uses 4 Kconfig variables right now which probably belong to the board
> >>Kconfig. Those are:
> >>
> >>CONFIG_ENV_IN_EMMC_BOOT -- tells that environment is in eMMC boot
> >> partition if defined
> >>
> >>CONFIG_EMMC_ENV_PART -- tells which boot partition environment should be
> >> stored in (either 1 or 2)
> >>
> >>CONFIG_EMMC_BOOT_PART -- which boot partition will be used by eMMC to
> >> read U-Boot/SPL binary for boot protocol (either 1 or 2.) That can be
> >> different from the environment partition
> >>
> >>CONFIG_EMMC_BOOT_ACK -- tells that eMMC should provide boot ACKs if
> >> defined
> >>
> >>Here is an excerpt from actual board Kconfig:
> >
> >I think what's missing is that in the other cases where we do
> >environment in the eMMC boot partitions we don't need the boot ack part.
> >Can you see if the existing hooks work, when you add in something for
> >boot ack?
> 
> Eh, I _DO_ use existing hook. And one of the parameters passed to that
> hook is boot ack (drivers/mmc/mmc_boot.c, line 101):
> 
> === Cut ===
> int mmc_set_part_conf(struct mmc *mmc, u8 ack, u8 part_num, u8 access)
> === Cut ===
> 
> I could've just set it to 0 unconditionally but there might be some board
> configs that might require it to be enabled so I made it configurable.
> 
> And I don't think we have any boards with environment in boot partition
> because there is simply no support for this in common/enc_mmc.c. Remember,

I've put environment on the boot partitions on the eMMC on Beaglebone
black for a number of years.  See include/configs/am335x_evm.h:
#elif defined(CONFIG_EMMC_BOOT)
#define CONFIG_ENV_IS_IN_MMC
#define CONFIG_SYS_MMC_ENV_DEV          1
#define CONFIG_SYS_MMC_ENV_PART         2
#define CONFIG_ENV_OFFSET               0x0
#define CONFIG_ENV_OFFSET_REDUND        (CONFIG_ENV_OFFSET +
CONFIG_ENV_SIZE)
#define CONFIG_SYS_REDUNDAND_ENVIRONMENT

Now, I fully accept that it's not working in your case and there must be
something further needed.

-- 
Tom
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