remove unused filesystem blocks from .zd files

[Quozl]

As part of #9411 it was requested that "OFW knows to only write blocks/chunks where data actually resides, rather than writing out a full 4gb of data every time".

Since OFW cannot reasonable identify which blocks contain data (requires extensive processing and support for ext2, ext3, and ext4), we instead move this responsibility to olpc-os-builder.

• fix olpc-os-builder to exclude unused filesystem blocks,
• fix XO-1.5 OpenFirmware to accept .zd files with missing blocks,
• fix XO-1.75 OpenFirmware to accept .zd files with missing blocks.

[Quozl]

olpc-os-builder and XO-1.5 OpenFirmware fixed.

[dsd]

Just XO-1.75 remaining then?

[Quozl]

Works on XO-1.75 A2 now, and a sparse variant of os4 is available for reproducing, assuming you have os4.zd already, and an account on crank, using this quick download method:

cp os4.zd os4-sparse.zd && \
rsync -avP dev.laptop.org:~quozl/public_html/fs-update-skip-unused-blocks/os4-sparse.zd .

What remains is for the XO-1.75 software builds to be sparse.

[Quozl]

XO-1.75 os9 not sparse. A sparse variant is available:

cp os9.zd os9-sparse.zd && \
rsync -avP dev.laptop.org:~quozl/public_html/fs-update-skip-unused-blocks/os9-sparse.zd .

[Quozl]

Builds for XO-1.75 are sparse, closing this ticket.