OpenWrt confused on partitions on Micro SD card?

Delbert Franz ddf at sonic.net
Thu Dec 16 17:14:17 EST 2010


I'm working up to some benchmarks on micro SD card and today I 
partitioned a 8 GB card into eight partitions: First 3 are primary and 
the remaining ones are logical.  Using cfdisk on the Nanonote numbers 
the partitions: p1 through p9 with the base name of "mmcblk0".  This 
all looks OK.  However, when the Nanonote is booted with the card 
present in the micro SD slot, it come ups during boot up showing the 
following pattern of partitions: 

p1 p2 p3 p4 <p5 p6 p7>

which is incorrect.  It should be 

p1 p2 p3 p4 < p5 p6 p7 p8 p9>.

When I hot-plug the card, the Nanonote tries to mount p4 but fails.  
Automounting is really confused!  It mounts partitions: p1, p5, p6, 
and p7.  One can mount p2 and p3 manually.  For some reason the 
automounter tries to mount p4 and gets all confused because it has no 
file system.  In the process it apparently "forgets" about p2 and p3:) 
And it does not know that p8 and p9 exist. 

There is then some problem in the part of the software that recognizes 
the partition table because it has it wrong and so the automounter 
gets confused.  

I have had no problem with four primary partitions but logical 
partitions are not being recognized properly.  So we can only get four 
partitions automounted.  We can get six mounted if we use three 
primary and three logical.  We have to mount p2 and p3 manually.  That 
seems to be the limit.  When I repartition the card to have eight 
logical partitions only p5, p6 and p7 are mounted.  Again the Nanonote 
tries to mount p1 and of course fails:) 

Anyone else had this problem or found a way to work around it?  

Thanks, 

      Delbert









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