Can L4 modules be accessed as files from L4Linux?

Dan Haim hdan at bgu.ac.il
Mon Mar 7 12:36:08 CET 2011


Hi,
If I include the CD-ROM driver in L4Linux then that would allow it complete
access to all files stored on the CD, wouln't it?
Anyway since I sent the previous mail yesterday I've already thought of the
second instance w/ virtual network solution (great minds think alike,
right?) but I was hoping for a more direct approach.

Anyway, many thanks!

-----Original Message-----
From: l4-hackers-bounces at os.inf.tu-dresden.de
[mailto:l4-hackers-bounces at os.inf.tu-dresden.de] On Behalf Of Adam
Lackorzynski
Sent: Monday, March 07, 2011 12:16 PM
To: l4-hackers at os.inf.tu-dresden.de
Subject: Re: Can L4 modules be accessed as files from L4Linux?

Hi,

On Sun Mar 06, 2011 at 18:45:49 +0200, Dan Haim wrote:
> I'm trying to find a solution to the following scenario - I want to 
> have an L4Linux instance running (from a CD) where the root filesystem 
> is several hundred MB's big, so it is not feasible to run it from a 
> ramdisk (the filesystem is larger than the amount of RAM available) - 
> I need to run it directly from the CD.
> A possible solution I'm thinkning about is to give the L4Linux 
> instance access to the CD-ROM drive, then store a SquashFS image as a 
> file on the drive and UnionFS it with a tmpfs when the system starts.
> Now here's the catch - While this solution may technically work, it is 
> still not 'good enough' because I can't give the L4Linux instance 
> direct access to the CD-ROM drive - I need to have it completely 
> isolated so a user working on the L4Linux instance will not have 
> access to any files stored on the CD (other than the SquashFS image) 
> even if he/she has root access over the L4Linux instance.
> I was thinking - is it possible to specify the SquashFS image as an L4 
> module and then somehow mount it from within L4Linux in-place (i.e. 
> without completely loading it to RAM)? Is there any other way to 
> accomplish what's needed in this scenario?

If the image is not loaded into RAM upon boot you'll need a driver for the
CD-ROM somewhere. Of course, L4Linux is a convenience place to have that
driver in. If that is not possible another L4Linux could be used that drives
the CD-ROM and both are connected via virtual network. Would that second
L4Linux be acceptable in your setup?



Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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