Disk layout for XO-1.5

Mitch Bradley wmb at laptop.org
Mon Jul 27 18:17:05 EDT 2009

This is a request for comments on a proposed disk layout for XO-1.5.

XO-1.5 will have "managed NAND" instead of raw NAND, so we can use 
conventional filesystems instead of e.g. JFFS2.


The internal NAND storage will be partitioned with an FDISK partition 
map, into three partitions:

/boot - 50 MB - FAT16
    Contains olpc.fth, vmlinuz, initrd, and any other files that OFW 
needs to access during booting

/ - 2 GB - ext4
    Contains system files

/home - remainder of storage - ext4
    Contains user files

Dual-boot systems might have additional partitions for Windows.  That 
will probably require storage devices > 4GB.

The partitions will be aligned to at least 1 MiB boundaries, ensuring 
that they do not split internal NAND erase blocks.

The choice of FAT for /boot makes it usable for both Linux and Windows.  
The choice of FAT16 avoids any possible patent issues surrounding 
FAT32.  FAT16 works fine for 50 MB partitions, using a 1K cluster size.  
With larger cluster sizes, there are several factors of two of headroom 
- and large clusters are not a problem for /boot, which tends to contain 
mostly large files.

More information about the Devel mailing list