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