[ixp1200] Re: Evaluation of Vera

[Scott C. Karlin]

On Thu, Jan 31, 2002 at 07:55:15PM +0800, Tan Chee Wei wrote:
> 
> There are a couple of problems and questions which I have while evaluating
> Vera's software and reading the Princeton papers. I appreciate advice.
> 1)I tested the software sgo on several machines. One persistent problem is
> that "sgo X.srec" could only execute once. The subsequent execution would
> lead to segmentation fault of sgo and the machine would normally freeze. 
> If "sgo X.srec" is used, I got the following errors:
> 
> +++runIXP1200:signal=0xffffffff expecting entry address(0xC1002000)
> +++IXP1200 is not a mem target on pri PCI and ...not a bus master on pri
> PCI.
> 
> If  "sgo -r X.srec" is used, more errors pop up:
> 
> +++Unable to handle kernel NULL pointer dereference at virtual address
> 00000000

Are you running pcirestore after you reset the board?

The cycle should be:

   1.  Boot the entire system
   2.  Load the vera.o module
   3.  Run your code (sgo X.srec)
   4.  Reset the ixp1200 board
          - if your program returns to minimon you can use Ctrl-R
          - otherwise, use the reset pin
   5.  Run pcirestore
   6.  Go to step 3.

When you load the vera.o module the first time, it records the settings
of the PCI configuration registers on the IXP1200 board.  Each time you
reset the board, the board's configuration is lost and it will not
respond to normal bus accesses.  However, Linux is not aware of this
and any attempt to access the board in an unconfigured state will
hang or crash the system.  The pcirestore command restores the saved
settings to the values it recorded when the module was first loaded.

Due to a known issue with the IXP1200, you cannot reliably reset the
chip with a write to its reset register from the PCI bus.  This is
what the '-r' option to sgo tries to do.  Some users have reported that
it works, others report that it does not.  My advice is to not use
the '-r' option.

> 2)How does one create the vth0,.... device interface on Pentium as described
> in the paper?  Will the forwarder's admission control that runs on Pentium
> be included in future release?

The released code doesn't create the vth devices.  It's definitely on our
"to do" list.  We don't have an estimated release date at this time.

Scott