1ROM-able zImage boot from eSD 2----------------------------- 3 4An ROM-able zImage compiled with ZBOOT_ROM_SDHI may be written to eSD and 5SuperH Mobile ARM will to boot directly from the SDHI hardware block. 6 7This is achieved by the mask ROM loading the first portion of the image into 8MERAM and then jumping to it. This portion contains loader code which 9copies the entire image to SDRAM and jumps to it. From there the zImage 10boot code proceeds as normal, uncompressing the image into its final 11location and then jumping to it. 12 13This code has been tested on an mackerel board using the developer 1A eSD 14boot mode which is configured using the following jumper settings. 15 16 8 7 6 5 4 3 2 1 17 x|x|x|x| |x|x| 18S4 -+-+-+-+-+-+-+- 19 | | | |x| | |x on 20 21The eSD card needs to be present in SDHI slot 1 (CN7). 22As such S1 and S33 also need to be configured as per 23the notes in arch/arm/mach-shmobile/board-mackerel.c. 24 25A partial zImage must be written to physical partition #1 (boot) 26of the eSD at sector 0 in vrl4 format. A utility vrl4 is supplied to 27accomplish this. 28 29e.g. 30 vrl4 < zImage | dd of=/dev/sdX bs=512 count=17 31 32A full copy of _the same_ zImage should be written to physical partition #1 33(boot) of the eSD at sector 0. This should _not_ be in vrl4 format. 34 35 vrl4 < zImage | dd of=/dev/sdX bs=512 36 37Note: The commands above assume that the physical partition has been 38switched. No such facility currently exists in the Linux Kernel. 39 40Physical partitions are described in the eSD specification. At the time of 41writing they are not the same as partitions that are typically configured 42using fdisk and visible through /proc/partitions 43