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- Board information
- -----------------
- The SBC produced by Phytec has a SOM based on a i.MX6Q.
- The SOM is sold in two versions, with eMMC or with NAND. Support
- here is for the SOM with NAND.
- The evaluation board "phyBoard-Mira" is thought to be used
- together with the SOM.
- More information on the board can be found on manufacturer's
- website:
- http://www.phytec.de/produkt/single-board-computer/phyboard-mira/
- http://www.phytec.de/fileadmin/user_upload/images/content/1.Products/SOMs/phyCORE-i.MX6/L-808e_1.pdf
- Building U-Boot
- -------------------------------
- $ make pcm058_defconfig
- $ make
- This generates the artifacts SPL and u-boot.img.
- The SOM can boot from NAND or from SD-Card, having the SPI-NOR
- as second option.
- The dip switch "DIP-1" on the board let choose between
- NAND and SD.
- DIP-1 set to off: Boot first from NAND, then try SPI
- DIP-1 set to on: Boot first from SD, then try SPI
- The bootloader was tested with DIP-1 set to on. If a SD-card
- is present, then the RBL tries to load SPL from the SD Card, if not,
- RBL loads from SPI-NOR. The SPL tries then to load from the same
- device where SPL was loaded (SD or SPI). Booting from NAND is
- not supported.
- Flashing U-Boot onto an SD card
- -------------------------------
- After a successful build, the generated SPL and U-boot binaries can be copied
- to an SD card. Adjust the SD card device as necessary:
- $ sudo dd if=u-boot-with-spl.imx of=/dev/mmcblk0 bs=1k seek=1
- This is equivalent to separately copying the SPL and U-boot using:
- $ sudo dd if=SPL of=/dev/mmcblk0 bs=1k seek=1
- $ sudo dd if=u-boot-dtb.img of=/dev/mmcblk0 bs=1k seek=197
- The default bootscripts expect a kernel fit-image file named "fitImage" in the
- first partition and Linux ext4 rootfs in the second partition.
- Flashing U-boot to the SPI Flash, for booting Linux from NAND
- -------------------------------------------------------------
- The SD card created above can also be used to install the SPL and U-boot into
- the SPI flash. Boot U-boot from the SD card as above, and stop at the autoboot.
- Then, clear the SPI flash:
- => sf probe
- => sf erase 0x0 0x1000000
- Load the equivalent of u-boot-with-spl.imx from the raw MMC into memory and
- copy to the SPI. The SPL is expected at an offset of 0x400, and its size is
- maximum 392*512-byte blocks in size, therefore 0x188 blocks, totaling 0x31000
- bytes. Assume U-boot should fit into 640KiB, therefore 0x500 512-byte blocks,
- totalling 0xA0000 bytes. Adding these together:
- => mmc read ${loadaddr} 0x2 0x688
- => sf write ${loadaddr} 0x400 0xD1000
- The SPL is located at offset 0x400, and U-boot at 0x31400 in SPI flash, as to
- match the SD Card layout. This would allow, instead of reading from the SD Card
- above, with networking and TFTP correctly configured, the equivalent of:
- => tftp u-boot-with-spl.imx
- => sf write ${fileaddr} 0x400 ${filesize}
- The default NAND bootscripts expect a single MTD partition named "rootfs",
- which in turn contains the UBI volumes "fit" (which contains the kernel fit-
- image) and "root" (which contains a ubifs root filesystem).
- The "bootm_size" variable in the environment
- --------------------------------------------
- By default, U-boot relocates the device tree towards the upper end of the RAM,
- which kernels using CONFIG_HIGHMEM=y may not be able to access during early
- boot. With the bootm_size variable set to 0x30000000, U-boot relocates the
- device tree to below this address instead.
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