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Date: Sun, 30 Jul 2006 22:03:54 +0200
From: Divacky Roman <xdivac02@stud.fit.vutbr.cz>
To: hackers@freebsd.org
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Subject: Re: VM question related to faults
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On Sun, Jul 30, 2006 at 12:57:32PM +0200, Divacky Roman wrote:
> hi,
> 
> while working on SoC linuxolator project I am in a need of this:
> 
> I need to do some operation on memory like mem1 = mem1 + mem2 etc.
> where the mem1/mem2 access can trigger fault. (memory not mapped or something)

to make it clear.. I am trying to access user-space memory from kernel.
This needs to be atomic (its an implementation of linux futexes)

I need to check from kernel if some memory is accessible and then perform an 
operation on this memory. All atomically.

hence I need two things - function which checks wheter the memory is accessible
and something which makes it atomic (some mutex/something which prevents other
process to enter VM to unmap/etc. the memory in question)

hope its a bit more clear now

roman