Disk layout for XO-1.5
pgf at laptop.org
Mon Jul 27 19:42:04 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
i would normally balk at such a large root partition, but if
we're planning on using the olpc-update symlink farm mechanism
for updates, then i think we'll be glad we have it. (i do think
we need to make sure we're not squandering space needlessly --
the current 1.1G seems large, even accounting for it being
uncompressed, and holding two desktops.)
> /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.
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> Devel at lists.laptop.org
paul fox, pgf at laptop.org
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