The barebox i.MX images have a preamble that pads the i.MX header to the offset expected by the BootROM. This allows writing barebox images directly to offset 0 on SD-Cards and eMMC user area. For some i.MX8M, these images can't be directly written to eMMC boot partitions and instead require special handling. Add a note about this to the documentation. Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> --- Documentation/boards/imx/nxp-imx8mm-evk.rst | 18 ++++++++++++++++ Documentation/boards/imx/nxp-imx8mn-evk.rst | 24 +++++++++++++++++++++ Documentation/boards/imx/nxp-imx8mp-evk.rst | 24 +++++++++++++++++++++ 3 files changed, 66 insertions(+) diff --git a/Documentation/boards/imx/nxp-imx8mm-evk.rst b/Documentation/boards/imx/nxp-imx8mm-evk.rst index c3cd35ae38a2..7ed7459c08a6 100644 --- a/Documentation/boards/imx/nxp-imx8mm-evk.rst +++ b/Documentation/boards/imx/nxp-imx8mm-evk.rst @@ -69,3 +69,21 @@ board for serial download mode as printed on the PCB. You can start barebox with the imx-usb-loader tool that comes with barebox like this: ./scripts/imx/imx-usb-loader images/barebox-nxp-imx8mm-evk.img + +Installing barebox +================== + +When the EVK is strapped to boot from eMMC, the i.MX8M bootrom will +consult the eMMC ext_csd register to determine whether to boot +from the active eMMC boot partition or from the user area. + +The same barebox image written to the start of the SD-Card can +be written to the start of the eMMC user area. Power-fail installation +to the eMMC boot partition requires special handling: + + - The barebox image must be written to the inactive boot partition, + then afterwards, the newly written boot partition is activated + (This is controlled by the barebox ``mmcX.boot`` variable). + +The ``barebox_update`` command takes care of this and need just be +supplied a barebox image as argument. diff --git a/Documentation/boards/imx/nxp-imx8mn-evk.rst b/Documentation/boards/imx/nxp-imx8mn-evk.rst index b920e22d33e9..4c07b949dafb 100644 --- a/Documentation/boards/imx/nxp-imx8mn-evk.rst +++ b/Documentation/boards/imx/nxp-imx8mn-evk.rst @@ -58,3 +58,27 @@ Build barebox make imx_v8_defconfig make + +Installing barebox +================== + +When the EVK is strapped to boot from eMMC, the i.MX8M bootrom will +consult the eMMC ext_csd register to determine whether to boot +from the active eMMC boot partition or from the user area. + +The same barebox image written to the start of the SD-Card can +be written to the start of the eMMC user area. Power-fail installation +to the eMMC boot partition requires special handling: + + - The barebox image must be written to the inactive boot partition, + then afterwards, the newly written boot partition is activated + (This is controlled by the barebox ``mmcX.boot`` variable). + + - The barebox image includes a 32KiB preamble that allows the image + to be directly writable to the start of the SD-Card or eMMC user area. + Unlike older i.MX8M, the i.MX8MN BootROM expects the bootloader to not + start as an offset when booting from eMMC boot partitions, thus the first + 32KiB must be stripped. + +The ``barebox_update`` command takes care of this and need just be +supplied a barebox image as argument. diff --git a/Documentation/boards/imx/nxp-imx8mp-evk.rst b/Documentation/boards/imx/nxp-imx8mp-evk.rst index 1074992f2f88..60e9f9eaea5d 100644 --- a/Documentation/boards/imx/nxp-imx8mp-evk.rst +++ b/Documentation/boards/imx/nxp-imx8mp-evk.rst @@ -66,3 +66,27 @@ Boot Configuration The NXP i.MX8MP-EVK board has four switches responsible for configuring bootsource/boot mode. The settings for the different boot sources are printed on the board. + +Installing barebox +================== + +When the EVK is strapped to boot from eMMC, the i.MX8M bootrom will +consult the eMMC ext_csd register to determine whether to boot +from the active eMMC boot partition or from the user area. + +The same barebox image written to the start of the SD-Card can +be written to the start of the eMMC user area. Power-fail installation +to the eMMC boot partition requires special handling: + + - The barebox image must be written to the inactive boot partition, + then afterwards, the newly written boot partition is activated + (This is controlled by the barebox ``mmcX.boot`` variable). + + - The barebox image includes a 32KiB preamble that allows the image + to be directly writable to the start of the SD-Card or eMMC user area. + Unlike older i.MX8M, the i.MX8MP BootROM expects the bootloader to not + start as an offset when booting from eMMC boot partitions, thus the first + 32KiB must be stripped. + +The ``barebox_update`` command takes care of this and need just be +supplied a barebox image as argument. -- 2.30.2
