[OE-core] [PATCH 1/2] wic/utils/partitionedfs.py: assemble .wic images as sparse files

[Alexander Kanevskiy]

On Sat, Apr 9, 2016 at 7:41 PM, Philip Balister <philip at balister.org> wrote:

> > This might be dangerous. Even in recent version of DD (coreutils 8.25),
> it
> > might not detect in source file mapped/unmapped blocks properly,
> > (just use is_nul() function to check if block contains only zeros,
> instead
> > of e.g. fiemap).
> > Result might be so, that in output file block which must be zeros is
> > actually become unmapped. And as consequence, if it might not be written
> to
> > destination drive.
>
> Does it work with bmaptool?
>

bmaptool can work with practically any sparse file (even if bmap file are
not provided) to flash it efficiently on raw device.
However, with such cases like "dd conv=sparse" it should be used with extra
caution, as some of needed zeroed blocks might not be written to
destination device.

Yocto bug #9099 now has two patches attached that adding initial bmap-tools
support to OE-core.
Those patches allows to create bmap files for simpler cases, like .hddimg
as well as shipping standalone version of bmaptool in deploy/tools/*
It probably would be content of next release, as I don't think anyone would
be merging them now.

For assembling images with wic, it would require a bit more work.

-- 
br, Alexander Kanevskiy
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