Commit | Line | Data |
---|---|---|
090ab3ff SH |
1 | ROM-able zImage boot from eSD |
2 | ----------------------------- | |
3 | ||
4 | An ROM-able zImage compiled with ZBOOT_ROM_SDHI may be written to eSD and | |
5 | SuperH Mobile ARM will to boot directly from the SDHI hardware block. | |
6 | ||
7 | This is achieved by the mask ROM loading the first portion of the image into | |
8 | MERAM and then jumping to it. This portion contains loader code which | |
9 | copies the entire image to SDRAM and jumps to it. From there the zImage | |
10 | boot code proceeds as normal, uncompressing the image into its final | |
11 | location and then jumping to it. | |
12 | ||
13 | This code has been tested on an mackerel board using the developer 1A eSD | |
14 | boot 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| | |
18 | S4 -+-+-+-+-+-+-+- | |
19 | | | | |x| | |x on | |
20 | ||
21 | The eSD card needs to be present in SDHI slot 1 (CN7). | |
22 | As such S1 and S33 also need to be configured as per | |
23 | the notes in arch/arm/mach-shmobile/board-mackerel.c. | |
24 | ||
25 | A partial zImage must be written to physical partition #1 (boot) | |
26 | of the eSD at sector 0 in vrl4 format. A utility vrl4 is supplied to | |
27 | accomplish this. | |
28 | ||
29 | e.g. | |
30 | vrl4 < zImage | dd of=/dev/sdX bs=512 count=17 | |
31 | ||
32 | A 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 | ||
37 | Note: The commands above assume that the physical partition has been | |
38 | switched. No such facility currently exists in the Linux Kernel. | |
39 | ||
40 | Physical partitions are described in the eSD specification. At the time of | |
41 | writing they are not the same as partitions that are typically configured | |
42 | using fdisk and visible through /proc/partitions |