Re: [PATCH 00/10] AXFS: Advanced XIP filesystem

[Greg Ungerer]

Hi Jared,

Jared Hulbert wrote:
> > That would be enough I think. If you could manually select
> > which files are contiguous-and-uncompressed that would be
> > useful for some too here.
>
> So.... If you don't have an MMU when do you call ->fault?  Does the
> noMMU code just loop through ->fault()ing all the pages in an mmap()?

Sort of. It actually just uses a single ->read to bring in
the entire file contents. There is a few limitations on the use
of mmap() for non-mmu. Documentation/nommu-mmap.txt gives
more details. With no MMU it does rely on being able to kmalloc()
a single RAM region big enough to hold the entire file.


> > One thing for sure is that many people who do non-MMU setups
> > are interested in XIP to get the space savings. These are very
> > often small devices with very constrained RAM and flash. (For
> > whatever it is worth single NOR flash only boards are common in
> > these smaller form factors :-)
>
> True.

Regards
Greg


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Greg Ungerer  --  Chief Software Dude       EMAIL:     gerg@xxxxxxxxxxxx
SnapGear -- a Secure Computing Company      PHONE:       +61 7 3435 2888
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