From owner-freebsd-current  Fri Jan 12 16:16: 1 2001
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Date: Fri, 12 Jan 2001 16:15:37 -0800
From: Alfred Perlstein <bright@wintelcom.net>
To: Andrew Gallatin <gallatin@cs.duke.edu>
Cc: Julian Elischer <julian@elischer.org>, phk@FreeBSD.ORG,
	freebsd-current@FreeBSD.ORG
Subject: Re: Running Linux kernel modules.
Message-ID: <20010112161535.B7240@fw.wintelcom.net>
References: <01C07BF3.695D3780.ggross@symark.com> <14942.32188.899333.434988@grasshopper.cs.duke.edu> <3A5F16D8.2E1B471C@elischer.org> <14943.37198.480690.136547@grasshopper.cs.duke.edu>
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* Andrew Gallatin <gallatin@cs.duke.edu> [010112 15:29] wrote:
> 
> Julian Elischer writes:
>  > > 
>  > > Isn't this gross?  Is there a better way?
>  > 
>  > I think that the better way is to actually have each open have a 
>  > different minor number.
>  > i.e. each process opens a different copy.
> 
>  > The way to achieve this best is with cloning devices.
>  > apply within phk for more info :-)
> 
> Does this mean that the processes can open /dev/foo0 twice and the
> driver sees a different minor number for each open?  Or does it mean
> that the process has to open /dev/foo0 and /dev/foo1?  
> 
> If the former, that's awesome!... How do I use it?

Well you have to write it, but you basically have the open(2)
syscall path optionally return a seperate void * 'cookie' that you
must pass into all operations (fileops) on that file.

It's not a major rewrite of any code, you just need an extra
parameter per fileop and store it in the struct file.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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