| ROM-able zImage boot from MMC |
| ----------------------------- |
| |
| An ROM-able zImage compiled with ZBOOT_ROM_MMCIF may be written to MMC and |
| SuperH Mobile ARM will to boot directly from the MMCIF hardware block. |
| |
| This is achieved by the mask ROM loading the first portion of the image into |
| MERAM and then jumping to it. This portion contains loader code which |
| copies the entire image to SDRAM and jumps to it. From there the zImage |
| boot code proceeds as normal, uncompressing the image into its final |
| location and then jumping to it. |
| |
| This code has been tested on an AP4EB board using the developer 1A eMMC |
| boot mode which is configured using the following jumper settings. |
| The board used for testing required a patched mask ROM in order for |
| this mode to function. |
| |
| 8 7 6 5 4 3 2 1 |
| x|x|x|x|x| |x| |
| S4 -+-+-+-+-+-+-+- |
| | | | | |x| |x on |
| |
| The zImage must be written to the MMC card at sector 1 (512 bytes) in |
| vrl4 format. A utility vrl4 is supplied to accomplish this. |
| |
| e.g. |
| vrl4 < zImage | dd of=/dev/sdX bs=512 seek=1 |
| |
| A dual-voltage MMC 4.0 card was used for testing. |
