[U-Boot] [PATCH] imx: ventana: update README for micro-SD boot medium

[Stefano Babic <sbabic@denx.de>]

On 21/05/2015 17:42, Tim Harvey wrote:
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> ---
>  board/gateworks/gw_ventana/README | 74 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 71 insertions(+), 3 deletions(-)
> 
> diff --git a/board/gateworks/gw_ventana/README b/board/gateworks/gw_ventana/README
> index 888657c..74698b7 100644
> --- a/board/gateworks/gw_ventana/README
> +++ b/board/gateworks/gw_ventana/README
> @@ -3,6 +3,12 @@ U-Boot for the Gateworks Ventana Product Family boards
>  This file contains information for the port of U-Boot to the Gateworks
>  Ventana Product family boards.
>  
> +The entire Ventana product family (http://www.gateworks.com/product#ventana)
> +is supported by a single bootloader build by using a common SPL and U-Boot
> +that dynamically determines the characterstics of the board at runtime via
> +information from an EEPROM on the board programmed at the factory and supports
> +all of the various boot mediums available.
> +
>  1. Secondary Program Loader (SPL)
>  ---------------------------------
>  
> @@ -28,8 +34,20 @@ To build U-Boot for the Gateworks Ventana product family:
>   make
>  
>  
> -3. Boot source, boot from NAND
> -------------------------------
> +3. Boot source:
> +---------------
> +
> +The Gateworks Ventana boards support booting from NAND or micro-SD depending
> +on the board model. The IMX6 BOOT ROM will choose a boot media based on eFUSE
> +settings programmed at the factory.
> +
> +Boards with NAND flash will always boot from NAND, and NAND-less boards will
> +always boot from micro-SD. However, it is possible to use the U-Boot bmode
> +command (or the technique it uses) to essentially bootstrap to another boot
> +media at runtime.
> +
> +3.1. boot from NAND
> +-------------------
>  
>  The i.MX6 BOOT ROM expects some structures that provide details of NAND layout
>  and bad block information (referred to as 'bootstreams') which are replicated
> @@ -77,7 +95,57 @@ via the mtdparts env var:
>   - rootfs: the rest
>  
>  This information is taken from:
> -  http://trac.gateworks.com/wiki/ventana/bootloader#NANDFLASH
> +  http://trac.gateworks.com/wiki/ventana/bootloader#nand
> +
> +More details about the i.MX6 BOOT ROM can be found in the IMX6 reference manual.
> +
> +3.1. boot from micro-SD
> +-----------------------
> +
> +When the IMX6 eFUSE settings have been factory programmed to boot from
> +micro-SD the SPL will be loaded from offset 0x400 (1KB). Once the SPL is
> +booted, it will load and execute U-boot (u-boot.img) from offset 69KB
> +on the micro-SD (defined by CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR).
> +
> +While it is technically possible to enable the SPL to be able to load
> +U-Boot from a file on a FAT/EXT filesystem on the micro-SD, we chose to
> +use raw micro-SD access to keep the code-size and boot time of the SPL down.
> +
> +For these reasons a micro-SD that will be used as an IMX6 primary boot
> +device must be carefully partitioned and prepared.
> +
> +The following shell commands are executed on a Linux host (adjust DEV to the
> +block storage device of your micro-SD):
> +
> + DEV=/dev/sdc
> + # zero out 1MB of device
> + sudo dd if=/dev/zero of=$DEV count=1 bs=1M oflag=sync status=none && sync
> + # copy SPL to 1KB offset
> + sudo dd if=SPL of=$DEV bs=1K seek=1 oflag=sync status=none && sync
> + # copy U-Boot to 69KB offset
> + sudo dd if=u-boot.img of=$DEV bs=1K seek=69 oflag=sync status=none && sync
> + # create a partition table with a single rootfs partition starting at 1MB
> + printf "1,,L\n" | sudo sfdisk --in-order --no-reread -L -uM $DEV && sync
> + # format partition
> + sudo mkfs.ext4 -L root ${DEV}1
> + # mount the partition
> + sudo udisks --mount ${DEV}1
> + # extract filesystem
> + sudo tar xvf rootfs.tar.gz -C /media/root
> + # flush and unmount
> + sync && sudo umount /media/root
> +
> +The above assumes the default Ventana micro-SD partitioning scheme
> + - spl    :   1KB-69KB  (68KB)  required by IMX6 BOOT ROM
> + - uboot  :  69KB-709KB (640KB) defined by
> +                                CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR
> + - env    : 709KB-965KB (256KB) defined by
> +                                CONFIG_ENV_MMC_SIZE
> +                                CONFIG_ENV_MMC_OFFSET_REDUND
> + - rootfs :   1MB-
> +
> +This information is taken from:
> +  http://trac.gateworks.com/wiki/ventana/bootloader#microsd
>  
>  More details about the i.MX6 BOOT ROM can be found in the IMX6 reference manual.
>  
> 
Applied to u-boot-imx, thanks!

Best regards,
Stefano Babic


-- 
=====================================================================
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================