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" Subject: Hard Reset of IXP1200 over PCI? To: ixp1200@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