Memory partitioning

Memory partitioning

[Santosh Eraniose]

Hi,
Is it possible to partition the MMU such that multiple OS
can run on the same platform.
In all examples I see like MKLinux , the mem mgmt of Linux is mapped to the
underlying Mach kernel.
The other extreme is as in RTAI (Real time App Interface), where the MMU is 
handled by linux, but the
scheduling is done by RTAI.

Thanks
Santosh Eraniose
-----------------------------------------------
Member Technical
Sony Software Architecture Lab
Bangalore
-----------------------------------------------

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Re: Memory partitioning

[Ralf Baechle]

On Tue, Aug 22, 2000 at 04:02:51PM +0530, Santosh Eraniose wrote:

> Is it possible to partition the MMU such that multiple OS
> can run on the same platform.
> In all examples I see like MKLinux , the mem mgmt of Linux is mapped to the
> underlying Mach kernel.
> The other extreme is as in RTAI (Real time App Interface), where the MMU is 
> handled by linux, but the
> scheduling is done by RTAI.

Several approaches:

 - IBM S390 can partition the hardware.  In cooperation with IBM's VM this
   allows to completly - and efficiently - subdivide the machine into multiple
   virtual machines.  VMs can even nest.
 - Less perfect due to not available VM-like software and no support of the
   hardware as on the S390 for example Sun's E10000 or SGI Origin 2000/3000
   offer partitioning.  This style of partitioning is mostly implemented
   by the hardware of the machines.

The two approaches guarantee that even a virtual machine or partition that goes nuts can't crash another virtual machine or partition.

 - Not implemented but in theory implementable would be multiple kernels
   running on top RTLinux's realtime kernel.

  Ralf
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Re: Memory partitioning

[Mark_H_Johnson]

Hmm. We've been looking into moving a real time computer emulation [to run
flight software in a simulator] to Linux and have similar problems. Our
solution doesn't involve partitioning the MMU though. Similar to the
MKLinux example below, we're willing to use the part of Linux memory
management where it helps - allocating storage and locking it into memory.
Where we've focused our attention is the handling of page faults & related
traps. We want something like a "secondary interrupt dispatch table" that
is enabled on a per process basis. There's some small overhead to do the
extra IF statement at the start of each interrupt handler, but it gives us
the means of selecting which code we want to run [standard Linux, RT Linux,
or our own]. Is that kind of capability what you are looking for or
something else?

--Mark H Johnson
  <mailto:Mark_H_Johnson@raytheon.com>


                                                                                                                    
                    Santosh                                                                                         
                    Eraniose             To:     Linux-MM@kvack.org                                                 
                    <santosh@sony        cc:     (bcc: Mark H Johnson/RTS/Raytheon/US)                              
                    .co.in>              Subject:     Memory partitioning                                           
                                                                                                                    
                    08/22/00                                                                                        
                    05:32 AM                                                                                        
                                                                                                                    
                                                                                                                    



Hi,
Is it possible to partition the MMU such that multiple OS
can run on the same platform.
In all examples I see like MKLinux , the mem mgmt of Linux is mapped to the
underlying Mach kernel.
The other extreme is as in RTAI (Real time App Interface), where the MMU is

handled by linux, but the
scheduling is done by RTAI.

Thanks
Santosh Eraniose
-----------------------------------------------
Member Technical
Sony Software Architecture Lab
Bangalore
-----------------------------------------------

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
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