[Arm-netbook] Booting from SD card with switch on so-dimm in other direction ...

[Adam Gill]

I never get this - even with the one you helped me with ....

Command (m for help): p

Disk /dev/mmcblk0: 1977 MB, 1977614336 bytes
61 heads, 62 sectors/track, 1021 cylinders
Units = cylinders of 3782 * 512 = 1936384 bytes

Luke Kenneth Casson Leighton wrote:
> On Wed, Mar 24, 2010 at 2:39 PM, Jonathan Ervine <jon.ervine at gmail.com> wrote:
>
>   
>> Moving the switch on my SO-DIMM leaves the netbook unbootable, regardless of whether the SD card is inserted. Pressing the power switch just flashes the light briefly.
>>     
>
>  ok  - i've been thinking about that: 2gb NAND flash drive sizes
> (cyls, sectors) are _different_ from SD card 2gb sizes.
>
>  so the trick of copying 2gb NAND to 2gb SD using dd isn't necessarily
> guaranteed to work.
>
>  only by getting u-boot at exactly the right point from the _end_ of
> the SD card will it be executed.
>
>  sooOoo.... could you check, jon, the message i sent earlier, confirm
> that the SD card cyls/sectors and size are identical to what i saw
> under fdisk, then copy that mmcblk0p1 using the dd command which skips
> to the end of the SD card?
>
>  ... actually, let me correc those instructions, here, because i got
> them rather wrong (mmblk0p1.bz2 not mmcblk0p1.bz2 etc.)
>
>
>
> you MUST use a 2gb SDcard for this to work, so if you use fdisk, it
> must show the same params as here:
>
> # fdisk /dev/mmcblk0
>
> Command (m for help): p
>
> Disk /dev/mmcblk0: 1977 MB, 1977614336 bytes
> 61 heads, 62 sectors/track, 1021 cylinders
> Units = cylinders of 3782 * 512 = 1936384 bytes
>
>
> if you have exactly that, then the following will work.
>
> # wget http://lkcl.net/arm_systems/CT-PC89E/mmcblk0p1.bz2
> # bunzip2 mmcblk0p1.bz2
> # dd if=mmcblk0p1 of=/dev/mmcblk0 seek=3672000 bs=512
>
>
> if you know what you're doing, you should be able to adapt that
> accordingly: subtract or add the appropriate number of 512-byte
> sectors onto the "seek=" parameter, depending on this formula:
>
>  seek = 3672000 + ( ( {your-drive-size-in-bytes}-1977614336 ) / 512 )
>
> i repeat because there seems to be some confusion about what's needed:
> formatting of the SD card IS NOT REQUIRED AND WILL MAKE ABSOLUTELY NO
> DIFFERENCE.  this is _direct_ copy and the ARM cpu uses _direct_
> reading, bypassing any need or requirement for any kind of
> "formatting" of any kind.
>
> also to recap: frans has suggested making modifications to the
> partition (which can be done safely) in particular making
> modifications to the u-boot parameters.  this is a good idea.
>
> l.
>
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