wildpossumboy wrote:
> --- In Michael Schmidt <> wrote:
>
>> wildpossumboy wrote:
>>> [...]
>>> Of course if I set Jumper 1 ON for booting the TS7800 on power-up does try
>>> to boot from the micro-SD card but stops there.
>>> But as I don't have any system or boot data on the card, the booting just
>>> "hangs".
>>>
>>> The TS7800 manual says that the TS7800 will try to boot firstly from the
>>> micro-SD card, then the standard SD card then on-board flash if it fails to
>>> boot by other means.
>>> That is my interruption of what is written in the Manual.
>>>
>>> However, my experience testing over six TS7800 systems is:
>>> They just hang awaiting micro-SD booting.
>>> The micro-SD card I am using are ext2 formatted, but contains only
>>> application information.
>
> << SNIP >>
>
>
>> The boot logic has no way of knowing whether or not a valid kernel is on
>> the card. I was under the impression that if you don't have any 0xDA
>> partitions it shouldn't try to boot anything, so if you want to leave
>> the card in at boot just partition it without these - Jesse is this
>> correct? So basically if it sees something it thinks could be the
>> kernel it will try to boot it. If there is nothing in the slot, then it
>> will skip to the next device.
>
> Hi Michael.
>
> I don't have any 0Xda (confirmed) partition(s) on the micro-SD device at all,
> so accordingly the device should not boot. I have only one partition 0x83
> (Linux). Am I correct in interpreting your comments above that any partition
> other than 0xda will cause the booting process to NOT boot from that device.
> Or did you mean that if the device has a 0xda partition it will not try to
> boot of the device? The second option makes more sense in a way.
There was a part that I forgot. The code that looks for the 0xDA
partition is in the MBR of the boot media. The bootrom of the 7800 only
checks for the presence of media and jumps to its MBR. Depending on
where the MBR of your media came from it may not have this code, in
which case the board would just hang. Likewise if you use the MBR code
we provide but there are no 0xDA partitions the board will hang also.
The purporse of the 0xDA value is as a marker to allow partitions to be
moved. (e.g. the kernel does not have to be the first partition, only
the first 0xDA partition)
> Could you kindly verify your understanding as I have to find a way of using
> the micro-SD card for application data.
If you want to use the micro-SD for data but not for booting it is
recommended to boot from the flash and then mount the micro-SD
partition. The idea behind checking the micro-SD before the regular SD
slot is that the regular SD can hold more data and is more easily
removable and thus is the more likely candidate for holding only data.
> OK, I could use the card for booting the kernel but as far as I understand
> from the documentation I forced in having fixed partition sizes for booting,
> hence any large flash device becomes useless for any more than 512KB. Is this
> also correct?
^^^MB?
You can resize the partitions to whatever sizes you need. The stock MBR
code will use the size of the 0xDA partitions to determine how much to
load.
> Is there a way to "fool" the system into allowing the remainder of disk space
> in another partition to be used for applications data?
> If your comment meant to say a partition formatted as 0xda, then would it
> suffice to create a boot partition formatted as 0xda, and place additional
> partitions using 0x83 etc...?
>
> Thanks for you inputs.
> Best regards.
> Grahame
______ Best Regards,
|__ __/ Michael Schmidt
|| Software Engineer
||echnologic Systems (EmbeddedARM.com)
|| (480) 16525 East Laser Drive
|/ 837-5200 Fountain Hills, AZ 85268
http://oz.embeddedarm.com/~michael
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