> Is there anything in the kernel that could be used to speed up the
> dumping of very large, very sparce files?

> For instance I would like to be able to verify the non-zero parts of
> the following file:

> $ ls -ls z
> 192 -rwxr-xr-x  1 dsl  wheel  14797279232 Jan 24 22:31 z

> without actually transferring 14Gb of data from kernel to user.
> (and maybe without filling all of physical memory with 0 bytes).

Well, it's only a little like what I assume you're looking for, but if
the file is on an FFS filesystem, I have code that knows how to read
the disk directly and detect holes in the file that way.

Drop me a line if you're interested in discussing it further.

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