Re: [uml-devel] When /tmp is not tmpfs.

[Blaisorblade <blaisorblade@yahoo.it>]

On Monday 28 November 2005 02:07, Rob Landley wrote:
> On Sunday 27 November 2005 12:31, Nix wrote:

> Did you catch Linus's long rant about how MAP_PRIVATE is deeply stupid and
> that Linux will never really implement it?

What's that?

> And you can fsync and do stuff like journaling within a file.  (Except with
> mmap it's msync.)

> No, just use the madvise(NO_SYNC).

Which doesn't exist.

> Then tmpfs becomes completely 
> irrelevant because any arbitrary file backed mapping can be treated as
> memory.  (Not pinned, but still treated as shared memory.)

> I vaguely remember some discussion about this on linux-kernel, some time
> ago. I wonder how it came out?  (2.6.15-rc2 mman.h doesn't show
> anything...)

What I remember is MADV_TRUNCATE / MADV_FREE / and so on by Badary Pulavarty - 
the equivalent of MADV_DONTNEED with additional truncation of the tmpfs pages 
you have mmaped.

Which is used for UML memory hotunplug patch from Jeff's. IIRC it's in -mm, 
but won't be in 2.6.15 at this point.

> > (security holes? but other users can't *see* that /tmp, which is why it's
> > mode 640, just like their $HOME...)

> Or you could just add the madvise() like I mentioned and forget about tmpfs
> completely.

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	

	
		
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