Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 17/20] FRV: Better mmap support in uClinux | Date | Fri, 19 Nov 2004 16:26:43 +0000 |
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> > (3) Files (and blockdevs) cannot be mapped shared since it is not > > really possible to honour this by writing any changes back to the > > backing device. > > [way behind on email] > > I think this could be done at msync, munmap and exit time? You end up > flushing the entire mapping, but it's still correct (and POSIX > compliant).
Don't forget write() too. If someone does a write, that would have to be written over the mapping too. Obviously this is not impossible.
> And, if you wanted to be really clever, you could store a hash of each > page to detect changes and avoid the extra I/O.
It'd probably have to be something like an md5 sum.
Okay, technically, we could probably emulate it, but is it worth it? I think it's something to bear in mind for another time.
More to the point, perhaps, is making shared memory stuff work.
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