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- ROM-able zImage boot from eSD
- -----------------------------
- An ROM-able zImage compiled with ZBOOT_ROM_SDHI may be written to eSD and
- SuperH Mobile ARM will to boot directly from the SDHI 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 mackerel board using the developer 1A eSD
- boot mode which is configured using the following jumper settings.
- 8 7 6 5 4 3 2 1
- x|x|x|x| |x|x|
- S4 -+-+-+-+-+-+-+-
- | | | |x| | |x on
- The eSD card needs to be present in SDHI slot 1 (CN7).
- As such S1 and S33 also need to be configured as per
- the notes in arch/arm/mach-shmobile/board-mackerel.c.
- A partial zImage must be written to physical partition #1 (boot)
- of the eSD at sector 0 in vrl4 format. A utility vrl4 is supplied to
- accomplish this.
- e.g.
- vrl4 < zImage | dd of=/dev/sdX bs=512 count=17
- A full copy of _the same_ zImage should be written to physical partition #1
- (boot) of the eSD at sector 0. This should _not_ be in vrl4 format.
- vrl4 < zImage | dd of=/dev/sdX bs=512
- Note: The commands above assume that the physical partition has been
- switched. No such facility currently exists in the Linux Kernel.
- Physical partitions are described in the eSD specification. At the time of
- writing they are not the same as partitions that are typically configured
- using fdisk and visible through /proc/partitions
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