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    x86: samus: Add a target to boot through TPL · 5744c87a
    Simon Glass authored
    
    
    Add a version of samus which supports booting from TPL to SPL and then
    to U-Boot. This allows TPL to select from an A or B SPL to support
    verified boot with field upgrade.
    
    Reviewed-by: Bin Meng's avatarBin Meng <bmeng.cn@gmail.com>
    Signed-off-by: Simon Glass's avatarSimon Glass <sjg@chromium.org>
    Series-to: u-boot
    Series-cc: bin
    Reviewed-by: Bin Meng's avatarBin Meng <bmeng.cn@gmail.com>
    Series-changes: 2
    - Sort defconfig and adjust it to build after rebase on maste
    Cover-letter:
    x86: Add support for booting from TPL
    At present SPL is used on 64-bit platforms, to allow SPL to be built as
    a 32-bit program and U-Boot proper to be built as 64-bit.
    
    However it is useful to be able to use SPL on any x86 platform, where
    U-Boot needs to be updated in the field. Then SPL can select which U-Boot
    to run (A or B) and most of the code can be updated. Similarly, using TPL
    allows both SPL and U-Boot to be updated. This is the best approach, since
    it means that all of U-Boot proper as well as SPL (in particular SDRAM
    init) can be updated in the field. This provides for the smallest possible
    amount of read-only (non-updateable) code: just the TPL code.
    
    This series contains a number of changes to allow x86 boards to use TPL,
    SPL and U-Boot proper. As a test, it is enabled for samus with a new
    chromebook_samus_tpl board.
    END
    5744c87a