| Simon Horman | f45b114 | 2011-01-11 04:01:08 +0100 | [diff] [blame] | 1 | ROM-able zImage boot from MMC |
| 2 | ----------------------------- |
| 3 | |
| 4 | An ROM-able zImage compiled with ZBOOT_ROM_MMCIF may be written to MMC and |
| 5 | SuperH Mobile ARM will to boot directly from the MMCIF hardware block. |
| 6 | |
| 7 | This is achieved by the mask ROM loading the first portion of the image into |
| 8 | MERAM and then jumping to it. This portion contains loader code which |
| 9 | copies the entire image to SDRAM and jumps to it. From there the zImage |
| 10 | boot code proceeds as normal, uncompressing the image into its final |
| 11 | location and then jumping to it. |
| 12 | |
| 13 | This code has been tested on an AP4EB board using the developer 1A eMMC |
| 14 | boot mode which is configured using the following jumper settings. |
| 15 | The board used for testing required a patched mask ROM in order for |
| 16 | this mode to function. |
| 17 | |
| 18 | 8 7 6 5 4 3 2 1 |
| 19 | x|x|x|x|x| |x| |
| 20 | S4 -+-+-+-+-+-+-+- |
| 21 | | | | | |x| |x on |
| 22 | |
| 23 | The zImage must be written to the MMC card at sector 1 (512 bytes) in |
| 24 | vrl4 format. A utility vrl4 is supplied to accomplish this. |
| 25 | |
| 26 | e.g. |
| 27 | vrl4 < zImage | dd of=/dev/sdX bs=512 seek=1 |
| 28 | |
| 29 | A dual-voltage MMC 4.0 card was used for testing. |