Hard Reset of IXP1200 over PCI?

[Scott C. Karlin]

I performed the experiment and answered my own question.

It seems that writing 0xFFFFFFFF to the IXP1200_RESET register
from the PCI bus does indeed reset the IXP1200.  As expected,
the reset knocks the IXP1200 off of the PCI bus.  However, once
I restored the PCI configuration registers to their original
state, the board worked fine.

Can anyone from Intel confirm (to the list) that the only reason
a PCI device should not write to the IXP1200_RESET register is
that the board will be deconfigured from the PCI bus?

Scott



> From: "Scott C. Karlin" <scott at CS.Princeton.EDU>
> Subject: Hard Reset of IXP1200 over PCI?
> To: ixp1200 at CS.Princeton.EDU
> Date: Wed, 14 Feb 2001 14:50:07 -0500 (EST)
> 
> I'd like to be able to perform a hard reset of the
> IXP1200 over the PCI bus.  Most of the documentation
> seems to indicate that I cannot do this.  However,
> the IXP1200 Programmer's Reference Manual seems to
> indicate that it might be possible (but not allowed).
> 
> Section 4.7.13 IXP1200_RESET indicates that the
> IXP1200_RESET register can be read and written
> from offset 0x7C.  However, the paragraph directly
> above says that "PCI devices must not write to this
> register."
> 
> What happens if I do?  (I assume that the IXP1200
> will reset and clear the PCI registers including the
> BAR set by the host machine.  If I promise to put the
> board back in the same place in the PCI memory map,
> will everything be OK?)
> 
> Scott