75XX XNAND: Difference between revisions

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The [[XNAND]] is our layer of software and an FPGA core which is designed to vastly increase the reliability of NAND access.  This board includes a 512MB flash chip, but the XNAND algorithm will limit this to a usable 256MB from redundancy.  The software layer to access the XNAND is implemented in userspace in conjunction with NBD (network block device).  You may want to refer to the [[nandctl]] page which will show more advanced usage, but by default the linuxrc script will mount the sd card with the following layout:
The XNAND is our layer of software and an FPGA core which is designed to vastly increase the reliability of NAND access.  This board includes a 512MB flash chip, but the XNAND algorithm will limit this to a usable 256MB from redundancy.  The software layer to access the XNAND is implemented in userspace in conjunction with NBD (network block device).  You may want to refer to the [[nandctl]] page which will show more advanced usage, but by default the linuxrc script will mount the sd card with the following layout:


   /dev/nbd0 - whole disk device of XNAND drive
   /dev/nbd0 - whole disk device of XNAND drive
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{{Note|NBD devices report their size as SIZE_MAX for more flexibility when using them with nandctl.  If you are formatting a partition or using dd you will need to specify the size of the block device or partition.}}
{{Note|NBD devices report their size as SIZE_MAX for more flexibility when using them with nandctl.  If you are formatting a partition or using dd you will need to specify the size of the block device or partition.}}
For more information on the [[XNAND]] layer, see [[XNAND|this]] page.

Revision as of 11:05, 20 December 2016

The XNAND is our layer of software and an FPGA core which is designed to vastly increase the reliability of NAND access. This board includes a 512MB flash chip, but the XNAND algorithm will limit this to a usable 256MB from redundancy. The software layer to access the XNAND is implemented in userspace in conjunction with NBD (network block device). You may want to refer to the nandctl page which will show more advanced usage, but by default the linuxrc script will mount the sd card with the following layout: 

 /dev/nbd0 - whole disk device of XNAND drive
 /dev/nbd1 - 1st partition (kernel partition)
 /dev/nbd2 - 2nd partition (EXT2 initrd)
 /dev/nbd3 - 3rd partition (~252MByte mini Debian EXT3 filesystem)
 /dev/nbd4 - 4th partition (unused)
Note: NBD devices report their size as SIZE_MAX for more flexibility when using them with nandctl. If you are formatting a partition or using dd you will need to specify the size of the block device or partition.
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