Re: Shared-Memory for the Hurd?

[Marcus Brinkmann]

On Fri, Dec 01, 2000 at 06:42:15AM +0100, Farid Hajji wrote:
> >      To conclude, the shm server would live in, e.g. /servers/shm.
> >      Inheriting from libtreefs or libdiskfs seems like a good idea
> >      (enabling you to expose the maps in that directory).  Using trivfs
> >      is a bad idea (I did it in my procfs:
> >      ftp://walfield.org/pub/people/neal/hurd/procfs; don't worry, it
> >      will not be going in CVS).
> libtreefs was what I had in mind for the "fullsized" shm-translator.
> About libdiskfs, I'm not sure yet (read: I must read more sources yet).
> Basically, I don't need a filesystem-backend (say ext2, ufs, ...),
> just a tree (directory) structure to hold, say /servers/shm/0,
> /servers/shm/1, ... libdiskfs would be useful for a memory-based
> filesystem, which is not exactly what I have in mind. But again
> I'll have to read more about libdiskfs before.

libdiskfs assumes a backing store (provided by storeio). If you don't have
this, libdiskfs probably isn't so good. libtreefs is designed to fill the
gap between libtrivfs and libdiskfs, but it is probably not finished. At
least it is not build currently. There isn't even a ChangeLog.

I don't know why Neal says libtrivfs doesn't fit the job, but I never tried
to provide a treefs with libtrivfs. There is also libnetfs, which is also
used by non-networked filesystems like usermux and hostmux, so maybe there
is some value in it.

For a very simple directory serving translator, look at /dev/fd/, which is
served by trans/magic.c

> Now I must first figure out how to use libtreefs/libdiskfs by
> writing a translator with dummy callbacks. If I get there, the
> rest will be much more easier.

Sounds good. As I said, with libtreefs, you are reviving a code four or five
years old. With libdiskfs, you are facing the omplexity of libstore and the
paging interface...

Marcus

-- 
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Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org
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