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[ts-7000] Re: TS-7800 micro-SD card usage

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Subject: [ts-7000] Re: TS-7800 micro-SD card usage
From: "wildpossumboy" <>
Date: Wed, 06 May 2009 05:36:42 -0000
--- In  Michael Schmidt <> wrote:


All sorted and running fine.
Thanks Michael.
Cheers. Grahame

>
> wildpossumboy wrote:
> > --- In  Michael Schmidt <michael@> 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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