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